Engine remanufacture by adhesively retained cylinder liners

A restoration sleeve for the remanufacture of cast iron engine blocks or aluminum blocks with cast iron liners includes a sleeve formed of cast iron and having a relatively thin wall, a selected length, an outer diameter to achieve a non-interference fit within an overbored cylinder, an inner diameter equal to the original specifications of the original manufacturer of the engine block, and a helical cross hatched inner surface finish. The sleeves are manufactured by placing an unfinished sleeve in a boring fixture, boring the inner surface to a selected diameter, transferring the bored sleeve to a honing fixture, and honing the inner surface to the required diameter and surface finish. An adhesive is applied to the restoration sleeve and the overbored block cylinders, and the sleeves are inserted into the overbored cylinders wherein the adhesive is allowed to cure to thereby adhesively retain the sleeves within the block. A fluorescent dye is used in the adhesive for inspection by ultraviolet light to insure continuous and complete application of the adhesive to the restoration sleeve and the bored cylinder surface.

BACKGROUND OF THE INVENTION 
The present invention relates to the restoration of engines and, more 
particularly, to the remanufacture of cast iron block engines and resin 
impregnated aluminum block engines having cast iron cylinder liners using 
thin walled prefinished and semifinished cylinder liners which are 
adhesively retained in a non-interference fit relationship within the 
rebored block cylinder or cylinder liners. 
Within a reciprocating engine, the space between each piston and its 
cylinder wall is sealed by several piston rings. Each ring is resiliently 
urged outward for sealing contact with the cylinder wall is maintained. 
During engine operation, sliding frictional contact between piston rings 
and cylinder walls wears the ring contact surfaces and cylinder walls. As 
wear progresses, compression is more difficult to maintain and, 
additionally, there is increased oil consumption and increased oil 
contamination from combustion products forced past the piston rings. 
In general, replacement parts and restoration methods are available for 
large engines and engines which are required to be highly reliable, such 
as aircraft engines. Many diesel engines are designed and built with 
replaceable cylinders, and replacement cylinder and piston sets are 
manufactured and made available for overhauling diesel engines. The same 
is often true of aircraft engines, particularly large engines. Smaller 
aircraft engines are usually restored using remanufactured cylinders 
wherein the inner cylinder surface is plated to build up wall thickness 
and then machined to the desired dimensions and tolerances. One aspect of 
such restoration operations is that each is very expensive and can only be 
justified economically in commercial operations or in situations in which 
the cost of replacement of the entire engine is prohibitive. 
In order to increase fuel economy by reducing overall vehicle weight, 
several automobile manufacturers have designed and produced engines 
wherein the cylinder block and heads, crankcase, and oil pan are formed of 
aluminum alloys. While such aluminum alloys perform adequately in a 
structural sense, they are too soft to stand up to high speed frictional 
loads and would wear quickly in such applications. To avoid this, other 
metals or materials are employed for components subject to friction, such 
as bearings. In particular, cast iron cylinder liners are employed for 
frictional sealing engagement with the piston rings. Such cylinder liners 
for aluminum block engines are referred to as "wet cylinder" liners 
because the engine coolant directly contacts the outer surfaces of such 
liners to carry away heat from engine combustion and piston friction. 
Occasionally, during the operation of a piston engine, the piston rod can 
become separated from either the piston or the crankshaft. This is 
referred to as "throwing a rod" and can be very damaging to cylinder walls 
and to other components within the engine. The usual result is a gouging 
of the cylinder wall. If the gouge is not too deep, the cylinder can often 
be repaired by boring out the affected cylinder and the insertion of a 
replacement cylinder which is then bored and honed to the required 
dimensions within the block. 
Because it is necessary for all the cylinders of an engine to have the same 
volumetric displacement for engine balance purposes and since it is not 
economical to bore out and reline the remaining cylinders, the usual 
procedure is to redimension all the cylinders, including the repaired 
cylinder, to a greater radius than the original dimensions and to install 
oversized pistons. In older engines which were not computer controlled and 
wherein emission standards were not so strict, such repair methods were 
usually adequate. However, such relining of cylinders of modern engines 
which changes the displacement of the engine causes operational problems 
since the control computer and pollution controls are set up for 
controlling the operation of an engine with a given displacement. Modern 
engine control computers can often detect differences in pollution control 
device performance resulting from as little as a one or two inch increase 
in displacement. Such a detected fault can cause a permanently illuminated 
"check engine" indicator, making such a rebuilt engine difficult to 
guarantee. Solution of this problem can require the expense of replacing 
pollution control devices, such as the catalytic converter. 
The conventional liner insertion process is to force a liner into the 
rebored cylinder using a hydraulic press. This results in an 
"interference" fit wherein the outer surfaces of the liner frictionally 
engage the inner surfaces of the rebored cylinder. Thus, an interference 
fit of a liner within a cylinder generates a radially outward pressure of 
the liner wall against the cylinder surface. In an engine block not 
originally designed for relining of the cylinders, an interference fit of 
a liner can stress and even distort the block. The cumulative distortion 
of relining all the cylinders in a block can result in rendering the block 
nonrebuildable. 
Because conventional automobile engines with cast iron blocks are 
manufactured in mass quantities, it is currently not economical to restore 
the worn cylinders of an engine block to their original specifications. In 
engines for which cylinder replacement is designed from the outset, the 
cylinder structures are relatively thick walled. This facilitates 
machining and honing of the inner cylinder surface since the cylinder 
structures are self-supporting and stiff enough that there is virtually no 
distortion of the cylinder wall during machining operations. This allows 
quick and accurate dimensioning and finishing of the inner cylinder 
surface. Such engines and replacement cylinders are also designed for 
relatively convenient replacement of worn cylinders without machining of 
the cylinder block. In the case of diesel engines, an upper lip of the 
cylinder engages a shoulder groove in the block while the lower end 
engages a similar shoulder. The cylinder is then held in place by the 
cylinder head. Adhesives are often used to seal between the upper and 
lower rims of the cylinder and the block to retain coolant within the 
water jacket of the cylinder block which otherwise would likely leak out 
of the water jacket and probably into the oil pan, contaminating the oil. 
Conventional automobile engines with cast iron blocks are not designed for 
cylinder replacement. The cylinder structure is cast as an integral part 
of the cylinder block and machined to the required cylinder dimensions. 
When cylinder repair is required, relatively thin walled cylinder liners 
are used. In such a case, machining of the cylinder liner occurs with the 
liner located within the block. The liner wall is, thus, supported by the 
portion of the original cylinder wall which remains. Because of the 
relative thinness of the walls of such liners and the difficulty of 
accurately machining and finishing the inner surface thereof, it has 
heretofore been considered impractical to supply such liners in a 
semifinished or prefinished condition, which would otherwise economize the 
restoration of such engine blocks to their original displacement 
specifications. 
There is another type of aluminum block engine with an aluminum head which 
is formed by a lost foam casting process and which is resin impregnated 
for liquid retention. The engine uses relatively thick walled cast iron 
cylinder liners interference fit within the aluminum cylinder bores which 
are cryogenically cold shrunk prior to insertion. Currently, such engines 
are provided in Saturn automobiles (General Motors) and may be provided in 
other cars in the future. It is reported that the cylinder liners of such 
engines can be overbored a maximum of 0.015 inch diametrically for 
rebuilding purposes. However, in a conventional engine rebuilding process, 
an overbore on the order of 0.020 inch is typical. Additionally, such a 
maximum allowable overbore would only for the engine to be rebuilt one 
time. Thus, as designed, such an engine cannot be rebuilt using 
conventional techniques. 
A theoretical alternative to conventional rebuilding techniques is to heat 
the block to 400.degree.-450.degree. F. and drive the old liners out. The 
differential thermal expansion rates of aluminum and iron loosens the grip 
of the aluminum cylinder bores on the iron liners. New iron liners, with 
the original manufacturer's specified diameter, could then be inserted 
using a cold shrink process. However, heating the block to such a 
temperature, which is considerably higher than normal operating 
temperatures, destroys the resin impregnation, which results in a porous 
block which will not reliably hold oil and coolant. 
Reimpregnation of the aluminum block with the resin is not practical 
because any contaminant of oil, grease, dirt, label adhesives, or paint 
would cause local imperfections in the impregnation process, such that 
these areas would remain porous. It would be extremely laborious and, 
thus, very expensive to even attempt to adequately clean such contaminants 
from all surfaces and passages of the block and virtually impossible to 
accomplish. Thus, such a rebuilding process for aluminum block engines 
with interference fit iron cylinder liners could not be economically 
carried out or guaranteed. 
SUMMARY OF THE INVENTION 
The present invention provides methods and apparatus for restoring 
interference fit cast iron liners of aluminum cylinder blocks of 
automobile engines, as well as conventional cast iron engine blocks, to 
their original manufacturer's displacement specifications by the use of 
semifinished or prefinished thin walled cylinder structures and improved 
methods of installation of such prefinished restoration cylinder 
structures. In particular, the restoration cylinders are adhesively 
retained in a non-interference fit relationship within the original 
cylinder structures. 
The restoration cylinders are formed of cast iron tubular stock having a 
wall thickness on the order of a tenth of an inch (100 mils) prior to 
prefinishing. The cylinders may be provided in a range of diameters, wall 
thicknesses, and lengths to accommodate the restoration of a wide variety 
of sizes of engine blocks. For a given engine block, the outer diameter of 
the sleeve is greater than the specified cylinder diameter of the engine 
block while the inner diameter is less than the specified cylinder 
diameter to allow for boring and honing of the inner surface of the sleeve 
to the required dimension and surface finish. As manufactured, the 
restoration sleeves may have the same inner diameter as originally 
specified for the new engine block, or original cylinder liners, and have 
a helical crosshatch surface pattern which facilitates the seating of 
piston rings within the restored cylinders. Such bored and honed sleeves 
are referred to herein as prefinished sleeves. Alternatively, the 
restoration sleeves may be provided in a bored, but not honed, condition 
to allow the engine rebuilder to hone the sleeve after installation in an 
engine block. Sleeves which are only bored are referred to herein as 
semifinished sleeves. 
The restoration cylinders or sleeves are positioned in jigs or fixtures for 
boring and honing operations. A boring fixture for the sleeves is formed 
by base plate and a vertically spaced upper plate. The base and upper 
plates have aligned apertures with diameters slightly greater than the 
diameter to which the sleeves will be bored. Each of the base apertures in 
the base plate has an upper shoulder or edge groove which positively 
locates the lower ends of the sleeves with respect to the base apertures. 
Similarly, the upper apertures have lower shoulders or edge grooves to 
receive and positively locate the upper ends of the sleeves. The base and 
upper plates have a plurality of apertures so that a number of sleeves can 
be bored in a batch operation. A plurality of unfinished sleeves are 
positioned in alignment with the base apertures and support the top plate 
which is positioned thereon. Regularly spaced over-center clamps are 
engaged between the base plate and the upper plate to clamp and fix the 
positions of the sleeves within the boring fixture. The sleeves are bored 
by a rotary boring machine, either simultaneously or one at a time 
depending on the nature of the boring machine, to bring the inner diameter 
of the sleeves to within a selected tolerance of the desired diameter. 
A honing fixture, if used, is similar in some respects to the boring 
fixture and is formed by a base plate and an upper plate with aligned 
apertures. The apertures of the plates have facing edge grooves to 
positively position the sleeves in alignment with the apertures. The 
prebored sleeves are clamped between the base and upper plates by sets of 
circumferentially spaced bolts which are tightened to a torque which will 
adequately fix the positions of the sleeves but not so tight as to distort 
the shape of the sleeves. 
The inner surfaces of the sleeves may be honed by a rotary honing machine 
having a honing head formed by a plurality of honing sticks positioned as 
cylindrical elements of the honing head. Preferably, the honing machine is 
of the type wherein the centrifugal pressure of the honing sticks against 
the inner surface of the sleeves as well as the rotational speed and 
vertical dwell of the honing head can be precisely controlled by 
programming or by mechanical setup. Proper control of the centrifugal 
pressure of the honing sticks avoids radial distortion of the sleeve wall, 
resulting in precise inner sleeve diameter and radial uniformity. The 
vertical dwell of the honing head is controlled in such a manner as to 
apply a helical crosshatch surface finish to the inner surfaces of the 
sleeves which is needed to promote proper seating of piston rings during 
operational break-in of the remanufactured engine. 
In order to support the sleeve wall, particularly during honing, the sleeve 
supporting fixtures may be used in cooperation with a sleeve supporting 
bladder. The bladder is annular in shape with a central opening within 
which a sleeve is positioned during the machining operation. The bladder 
is inflated with a gas or liquid to engage an inner wall of the bladder 
with the outer surface of the sleeve wall to resist the radial pressure of 
the machining operation to thereby avoid radial distortion of the sleeve 
wall during machining. This enhances the precision of the honing operation 
and results in greater radial uniformity of the inner surface of the 
sleeve. 
Alternatively, the present invention contemplates other methods and 
apparatus or fixtures for supporting the restoration sleeves during 
machining operations. In a clam shell or separating block fixture, a 
support block is formed in halves which are slidably supported on tracks 
or guides of a support plate for movement toward and away from one another 
by linear motors, such as hydraulic cylinders. A sleeve receiving cylinder 
recess, of a diameter to fit the sleeve stock to be machined, is bored in 
the support block halves, half the recess in each block half. A sleeve is 
positioned in the recess between the separated block halves, and the block 
halves are closed to snugly clamp the sleeve therebetween. The cylinder 
surface of the recess of the block prevents the pressure of the boring 
tool or the honing head from distorting the wall of the sleeve during 
machining operations. The clam shell type of fixture is best suited to 
high volume manufacturing operations where the cost of providing a set of 
block halves for each size of sleeve to be manufactured can be more 
readily justified. The support block may be sized and bored to 
simultaneously support a plurality of sleeves. The outer cylindrical 
surfaces of the sleeves are machined to bring their radial uniformity to a 
selected tolerance using a centerless grinding process. 
Engine block restoration sleeves manufactured and prefinished or 
semifinished in a variety of sizes by the above described processes are 
stockpiled for later installation in engine block cylinders. When an 
engine block is to be remanufactured, the cylinders of a cast iron block 
engine, or the existing cast iron cylinder liners of an aluminum block 
engine, are overbored to a diameter which will achieve a selected degree 
of clearance or tightness with the installed cylinder sleeves. Sleeves of 
the proper size to restore the cylinder block to its original cylinder 
specifications are then inserted into the overbored cylinders. 
A preferred sleeve insertion process in the present invention is to 
overbore the original cylinders to a diameter just slightly greater than 
the outer diameter of the restoration sleeves to achieve a 
non-interference fit of the sleeves within the rebored cylinders 
structures and to adhesively retain the sleeves within the overbored 
cylinder structures. The original cylinders are overbored to a clearance 
of about two to four thousandths of an inch (0.025 to 0.05 millimeters) 
relative to the outer diameter of the replacement cylinders. An adhesive 
is then applied to the overbored cylinder surfaces and the outer surfaces 
of the restoration sleeves, and the sleeves are inserted into the 
overbored cylinders where the adhesive is allowed to cure. The adhesive 
used is preferably an anaerobically curing adhesive which is tolerant of 
the operating temperatures of the engine and which does not interfere with 
the transfer of heat from the sleeves through the original cylinders. 
Certain kinds of acrylic adhesives of this type are known and used in 
various applications in the automotive industry, such as adhesives of the 
type known as methyl acid/methyl acrylic ester adhesives. Curing of such 
adhesives is caused by a combination of pressure and a lack of oxygen. 
A even, continuous layer of adhesive without gaps is required to provide 
even transfer of heat from within the cylinders through the restoration 
sleeves to the engine block and thereby avoid localized overheating of the 
sleeves. In order to insure that a continuous layer of adhesive has been 
applied to the sleeve and the cylinder, the present invention provides the 
adhesive with a dye which is fluorescent in the presence of ultraviolet 
light. The dye is an ultraviolet light sensitive organic fluorescent dye. 
After the adhesive is applied to the machined cylinder surface or the 
sleeve outer surface, either or both may be inspected using ultraviolet 
light for gaps in the adhesive coverage. Any such gaps can be touched up 
prior to insertion of the sleeve into the cylinder. 
The present invention provides processes for economically remanufacturing 
aluminum engine blocks with interference fit cast iron cylinder liners, as 
well as cast iron blocks used in common automobiles. The most critical 
aspect of manufacturing the restoration sleeves, which is the honing and 
surface finishing process, may be carried out on a large scale which is a 
more efficient use of the expensive honing machinery and specialized 
machinist skills. The restoration sleeve insertion process does not 
require that the sleeve be forced into the block cylinder, which avoids 
the potential for distortion of the sleeve wall and other components 
within the engine block by such forced insertion. Thus, the efforts of an 
engine rebuilding shop in remanufacturing an engine block are 
substantially reduced by using the prefinished cylinders and method of 
adhesive installation of the present invention, without compromising the 
quality of the end product. 
Alternatively, the restoration sleeves may be provided as semifinished. The 
semifinished sleeves are installed in the same manner as the prefinished 
sleeves, but the engine rebuilder must then hone the inner surface of the 
sleeve to the final inner diameter and surface finish. Some rebuilders 
prefer to do the final honing in their own shops. 
Although adhesive retention of the restoration cylinders in a 
non-interference fit relationship within the rebored cylinders is 
preferred, the present invention provides an alternative method of 
installing the restoration cylinders in an engine block. The block 
cylinders are overbored for an interference fit of the replacement 
cylinders therein, and the replacement cylinders are cold shrunk prior to 
insertion. The overboring process must be accomplished with a high degree 
of precision and regularity, as compared to the boring process used in 
conventional cylinder repair processes, since any irregularity of the 
cylinders will be transferred to the cylinder sleeve which is installed 
and since no further machining of the installed sleeve will occur. Cold 
shrinking contracts the sleeves which can be inserted into with little or 
no resistance. As the temperature of the sleeves rises to equilibrium with 
the block, the sleeves expand to frictionally engage the overbored 
cylinders. It should be noted that the cold shrunk sleeves must be handled 
using refrigerated tools to avoid localized warming of portions of the 
sleeves which can cause distortions and possible stresses and consequent 
failure of the sleeves during operation of the engine. 
Although the engine block overboring process requires a fair degree of 
precision and the cold shrinking of the sleeves prior to insertion in the 
engine blocks requires the provision of specialized refrigeration 
equipment, the overall process of remanufacturing an engine block at an 
engine rebuilder's facility is simplified and, thereby, economized. 
OBJECTS AND ADVANTAGES OF THE INVENTION 
The principal objects of the present invention are: to provide apparatus 
and methods for remanufacturing or restoring the cylinders of cast iron 
cylinder blocks of conventional automobile engines and engine blocks with 
cast iron liners to the original cylinder specifications of the original 
engine manufacturer; to provide such apparatus and methods for 
remanufacturing engines which are not originally designed to accommodate 
relining of the cylinders thereof; to provide, particularly, semifinished 
or prefinished restoration cylinders for cast iron engine blocks and 
aluminum blocks with cast iron liners; to provide such restoration 
cylinders or cylinder sleeves which are formed of cast iron of a selected 
length, outer diameter, inner diameter, and inner surface finish; to 
provide such replacement cylinders which have an inner diameter equal to 
the original manufacturer's specified diameter for the particular engine 
and which have a helical crosshatch surface finish to aid in piston ring 
seating; to provide such restoration cylinders which can be inserted into 
the bored out cylinders of the engine block to be restored; to provide 
fixtures for supporting such restoration cylinders during boring and 
honing operations to manufacture the cylinders; to provide such fixtures 
including a base plate and an upper plate, the plates having aligned 
apertures which are grooved on facing sides to align the restoration 
cylinders with the apertures, and the base and upper plates being clamped 
into engagement with the cylinders to fix the positions thereof during 
machining; to provide apparatus to support the walls of the cylinders 
during machining to avoid distortion of the walls by radial force or 
pressure of the machine tools; to provide an annular bladder within which 
a restoration cylinder is received and which is inflated to engage an 
inner wall of the bladder with the outer surface of the sleeve wall to 
resist distortion of the sleeve wall during machining; to provide a clam 
shell or separating block fixture formed of block halves with halves of a 
sleeve receiving recess bored therein, the block halves slidably mounted 
on a support plate and moved toward and away from one another by linear 
motors to support the entire wall of a sleeve during machining; to provide 
a method of installation of such restoration cylinders into an engine 
block; to provide a preferred installation method in which the restoration 
cylinders are installed in a non-interference fit relationship within the 
cylinder structures to be restored to avoid stressing or distorting the 
engine block and the sleeves; to provide such a preferred method including 
overboring the existing block cylinders to a diameter slightly greater 
than the outer diameter of the restoration cylinders and adhesively 
retaining the restoration cylinders in the overbored cylinders; to provide 
such a preferred installation method which uses an anaerobically curing, 
noninsulating adhesive; to provide such an installation method which uses 
an adhesive having a dye which is fluorescent in the presence of 
ultraviolet light which facilitates inspection of the sleeve or cylinder 
for gaps in the application of the adhesive; to provide an alternative 
installation method including overboring the existing cylinders of the 
engine block to a diameter which will cause the restoration cylinders to 
be frictionally retained in the overbored cylinders; and to provide such 
apparatus and methods for remanufacturing cast iron engine blocks which 
are economical to manufacture and carry out, which are capable of a high 
degree of precision, and which are particularly well adapted for their 
intended purpose. 
Other objects and advantages of this invention will become apparent from 
the following description taken in conjunction with the accompanying 
drawings wherein are set forth, by way of illustration and example, 
certain embodiments of this invention. 
The drawings constitute a part of this specification and include exemplary 
embodiments of the present invention and illustrate various objects and 
features thereof.

DETAILED DESCRIPTION OF THE INVENTION 
As required, detailed embodiments of the present invention are disclosed 
herein; however, it is to be understood that the disclosed embodiments are 
merely exemplary of the invention, which may be embodied in various forms. 
Therefore, specific structural and functional details disclosed herein are 
not to be interpreted as limiting, but merely as a basis for the claims 
and as a representative basis for teaching one skilled in the art to 
variously employ the present invention in virtually any appropriately 
detailed structure. 
Referring to the drawings in more detail: 
The reference numeral 1 generally designates a restoration sleeve or 
replacement cylinder for the remanufacture of a cast iron engine block 2 
(FIG. 7) or for the remanufacture of an aluminum block engine having cast 
iron liners (FIGS. 12-14). The sleeves 1 are preferably positioned in a 
non-interference fit within the rebored cylinder structures and adhesively 
retained therein. 
The replacement or restoration cylinder 1 generally includes a relatively 
thin cylindrical wall 3 having an outer cylindrical surface 4 and an inner 
cylindrical surface 5. The cylinder 1 has a top rim 6 and a bottom rim 7 
which is provided with a chamfer or bevel 8 to facilitate insertion of the 
cylinder 1 into the block 2. The inner cylindrical surface 5 of the 
cylinder 1 may be provided with a helical crosshatch surface finish, 
indicated at 9, which aids in seating of piston rings 10 when the 
remanufactured engine block 2 is being broken in. 
The cylinder or sleeve 1 is formed of tubular cast iron stock which is 
similar to the metal from which the block 2 is cast to provide for similar 
thermal expansion and contraction characteristics. The stock from which 
the cylinder 1 is manufactured preferably has a minimum wall thickness 
which will allow convenient machining to minimize the amount of material 
which will need to be bored out of the block 2 to accommodate the cylinder 
1. The thickness of the wall 3 is substantially less than a thickness 
which would allow the wall 3 to withstand cylinder combustion pressure and 
piston ring bearing pressure without external support. The initial wall 
thickness may, for example, be approximately one tenth of an inch, which 
is on the order of about two millimeters. The cylinders 1 may be 
manufactured in a variety of lengths and diameters to provide for the 
remanufacture a wide variety of engine blocks 2. In general, the process 
for manufacturing the cylinders 1 includes the steps of supporting a 
plurality the cylinders 1 and boring the inner cylindrical surface 5 to 
slightly less than the desired final cylinder diameter. The outer 
cylindrical surface 4 is preferably machined to a selected radial 
uniformity, such as a radial variation of less than one half mil, by a 
centerless grinding process (not shown). At this point, the cylinder 1 is 
considered to be semifinished and may be provided to engine rebuilders in 
this condition for final finishing by the rebuilder. If the cylinder is to 
be completely prefinished, then the inner surface 5 is honed to achieve 
the desired radius, radial uniformity, and surface finish. 
FIGS. 2 and 3 illustrate a boring jig or fixture 15 in which the cylinders 
1 are supported during the boring operation. The illustrated boring 
fixture 15 includes a floor plate 16 having a plurality of vertical plates 
17 upstanding therefrom. A base plate 18 is supported by the vertical 
plates 17 and has a plurality of base apertures 19 formed therein. As 
shown in FIG. 3, each base aperture 19 has an edge groove or shoulder 20 
formed about an upper edge of the aperture 19. The groove 20 provides for 
positive positioning of the lower end 7 of a cylinder 1 in relation to the 
aperture 19. A plurality of cylinders 1 are received in the grooves 20 of 
the apertures 19, and an upper plate 21, having a plurality of upper 
apertures 22, is positioned on the cylinders 1 with the apertures 22 in 
alignment with the cylinders 1 and base apertures 19. Each of the upper 
apertures 22 has a lower edge groove or shoulder 20, similar to the groove 
20 of the base apertures 19, which is positioned on a lower side of the 
upper plate 21 to be engaged by the upper end 6 of the cylinder 1. 
The cylinders 1 are clamped between the base plate 18 and the upper plate 
21 of the boring fixture 15 by means of over-center clamp devices 24. 
Alternatively, other means of clamping the cylinders 1 between the base 
plate 18 and the upper plate 21 can be employed. The base plate 18 has a 
plurality of clamp mounting brackets 25 distributed thereabout, and the 
upper plate has a plurality of clamp receiving brackets 26 positioned to 
align with the brackets 25. The clamp devices 24 are configured to clamp 
the cylinders 1 tightly enough to fix the cylinders 1 in place without 
distorting the walls 3 thereof. The inner surfaces 5 of the cylinders 1 
are bored by a rotary cutting head 28 which is movable vertically to bore 
the length of the cylinders 1. The boring head 28 may be a component of a 
machine tool such as the Berco/Peterson Bore Wizard. 
FIGS. 4-6 illustrate a honing jig or fixture 30 for supporting the 
cylinders 1 during honing operations for bringing the cylinders 1 to a 
prefinished state. The illustrated honing fixture 30 includes a pair of 
legs 32 (one of which is shown) resting on respective feet 33. The legs 32 
are engaged by a pair of guide rails 34 which provides for accurate 
placement of the fixture 30 with respect to a honing head 35. The legs 32 
support a base plate 37 having a plurality of base apertures 38 formed 
therethrough. An upper plate 39 also has a plurality of upper apertures 40 
formed therein which are alignable with the base apertures 38. The lower 
edges of the upper apertures 40 have edge grooves or shoulders 41, and the 
upper edges of the base apertures 38 have similar grooves 41. The grooves 
41 positively align the cylinders 1 with the base apertures 38 and upper 
apertures 40 by engaging the upper edges 6 and lower edges 7 of the 
cylinders 1. 
The cylinders 1 are clamped between the base plate 37 and upper plate 39 of 
the honing fixture 30 by means of sets of bolts 43 which are distributed 
regularly about the apertures 38 and 40. The bolts 43 are threaded into 
the base plate 37 and are tightened to a selected torque which is 
sufficient to fix the positions of the cylinders 1 within the honing 
fixture 30 but not tight enough to distort the walls 3 of the cylinders 1. 
The bolts 43 are preferably positioned as close to the clamped cylinders 1 
as possible to avoid flexure of the base and upper plates 37 and 39 during 
tightening of the bolts 43. 
The honing head 35 is formed by a plurality of honing sticks 45 which are 
positioned as cylindrical elements of the honing head 35. The honing 
sticks 45 are covered with a very hard abrasive, such as diamond based 
abrasives. The honing head 35 is a component of a honing machine 46 which 
is preferably either programmable or mechanically set up to control the 
rotational speed of the head 35, its vertical speed and position or dwell, 
and the radially outward or centrifugal pressure which the honing sticks 
45 exert against the inner surface 5 of the cylinders 1 during the honing 
process. The honing machine 47 may, for example, be a model number CV616 
Cylinder Hone, as manufactured by Sunnen Products of St. Louis, Mo. 
Control of the honing pressure allows the honing head 35 to finish the 
inner surface 5 of a cylinder 1 without distorting the wall 3 thereof, 
which would result in an irregular shape to the inner surface 5. Control 
of the honing pressure along with the vertical speed and dwell of the 
honing head 35 allows the application of the helical crosshatch finish 9 
on the inner surfaces 5 of the cylinders 1. Once the cylinders 1 have been 
honed, they can be protectively packaged and shipped to engine rebuilding 
facilities for subsequent remanufacturing of engine blocks 2 of an 
appropriate size or warehoused for order by such rebuilding facilities. 
FIG. 10 diagrammatically illustrates a method or process 49 for 
remanufacturing a cast iron engine block using the prefinished cylinders 1 
according to the present invention. At 50, the cylinders or sleeves 1 are 
supported, as by use of the boring fixture 15 or the honing fixture 30. At 
51, the sleeves 1 are bored, as by the boring head 28 then honed at 52 to 
a prefinished condition. When an engine block 2 is to be remanufactured, 
the worn cylinders 53 (FIG. 7) are overbored at 54 to receive the sleeves 
1 with a slight clearance or non-interference fit between the outer 
cylindrical surface 4 of the sleeves 1 and a cylindrical surface 55 of the 
block cylinders 55. The diameter of the overbored block cylinders 53 may 
exceed the outer diameter of the sleeves 1 by an amount on the order of 
one to two thousandths of an inch (0.025 to 0.05 millimeters). 
In order to minimize distortion of the engine block 2 during the boring 
step 54 and thereby increase the accuracy of the boring step 54, a torque 
plate (not shown) can be bolted to the block 2. Such a torque plate may be 
formed of iron, steel, or even aluminum and has apertures which are 
slightly larger than the final diameter of the overbored block cylinders 
53. The torque plate also has bolt holes which align with the cylinder 
head bolt holes (not shown) of the block 2. The torque plate is simply 
bolted onto the block 2 in place of the cylinder head (not shown). 
At 56, an adhesive is applied to the inner surface 55 of the block 
cylinders 53 and the outer surface 4 of the sleeves 1. The adhesive is 
preferably an anaerobically curing adhesive which will not breakdown at 
the operating temperatures of the engine employing the engine block 2 and 
which will not interfere with the transfer of heat from the sleeve 1 to 
the block 2 during operation. There are types of acrylic adhesives which 
are known in the automotive industry which are appropriate for use in the 
engine remanufacturing method 49 of the present invention. The sleeves 1 
with adhesive applied and then inserted into the block cylinders 35 at 57 
and the adhesive is allowed to cure at 58. The clearance of the overbored 
cylinders 35 relative to the sleeves 1 facilitates insertion of the 
sleeves 1 such that only minimal force is required for the insertion step. 
The result is that the sleeves 1 are not distorted by the insertion step 
57 nor by slight diametric irregularities of the overbored block cylinders 
53. Importantly, the engine block 2 is also not distorted by insertion of 
the sleeves 1 thereinto. Thus, fairly average sized engine rebuilding 
shops can rebuild engine blocks 2 with a high degree of accuracy and 
economy using the prefinished replacement cylinders or sleeves 1 in the 
method 49 of the present invention. 
FIG. 8 illustrates an alternative fixture 60 for use in fixing the position 
of a replacement cylinder 1 during boring and honing thereof. The fixture 
60 is referred to as a clam shell or separating block type of fixture. The 
fixture 60 includes a support block 61 which is formed in block halves 62. 
Each block half 62 is slidably mounted in guide slots or tracks 63, as by 
guide followers 64, the slots 63 being formed in a support plate 65. Each 
block half 62 has a respective linear motor 66 connected between it and 
the support plate 65 to enable opposed movement of the block halves 62 
toward and away from one another. 
A cylindrical recess 69 is bored through the block halves 62 at the parting 
interface therebetween. Each block half 62 has a semi-cylindrical surface 
70 of the recess 69 which has a radius sized to closely engage the outer 
cylindrical surface 4 of a cylinder 1 to thereby radially support the wall 
3 of the cylinder 1. Such support prevents radial distortion of the 
cylinder wall 3 during machining of the inner surface 5. The block halves 
62 are separated to receive a cylinder 1 in the recess 69 and closed to 
clamp the block halves 69 about the cylinder 1. The clamping force of the 
block halves 62 fixes the position of the cylinder 1 during rotary 
machining operations thereon. The fixture 60 may be used to support a 
cylinder 1 during both boring and honing of the inner surface 5 thereof, 
or separate fixtures 60 may be provided for the boring and honing 
operations. 
FIG. 9 illustrates a modified fixture 80, such as a honing fixture, which 
incorporates an annular bladder 81 to radially support the wall 3 of a 
replacement cylinder 1 during machining of the inner surface 5 thereof. 
The fixture 80 includes a base plate 82 and a top plate 83 which are 
substantially similar to the base plate 37 and upper plate 39 of the 
honing fixture 30. The plates 82 and 83 clamp a cylinder 1 therebetween by 
the use of clamping bolts 84 which extend through the upper plate 83 and 
are threaded into the base plate 82. 
The bladder 81 is positioned between the plates 82 and 83 and is formed of 
a somewhat flexible material such as a rubber, plastic, or the like. An 
inner wall 85 of the bladder 81 is positioned to surround the cylinder 1. 
When inflated, as by a gas such as air or a liquid, the inner wall 85 
compressively engages the wall 3 of the cylinder 1 whereby the pressure 
within the bladder 81 resists radial deformation of the cylinder 1 to 
result in more accurate machining. The modified fixture 80 is more 
appropriately used for the honing of the cylinder 1 since the honing 
operation requires much higher precision than the boring operation. When 
the bladder 81 is deflated, the inner wall 85 loosens from engagement with 
the cylinder 1 whereby the finished cylinder 1 can be removed from the 
fixture 80 and another prebored cylinder 1 inserted for honing. 
FIG. 11 diagrammatically illustrates an alternative method or process 89 
for remanufacturing a cast iron engine block using the prefinished 
cylinders 1 according to the present invention. At 90, the cylinders or 
sleeves 1 are supported, as by use of the boring fixture 15 or the honing 
fixture 30. At 91, the sleeves 1 are bored, as by the boring head 28 then 
honed at 92 to a prefinished condition. When an engine block 2 is to be 
remanufactured, the worn cylinders 53 are overbored at 94 for an 
interference fit with the sleeves 1. At 95, the prefinished sleeves or 
cylinders 1 are cold shrunk to reduce the outer diameter thereof to 
facilitate insertion at 96 of the cold shrunk sleeves 1 into the overbored 
cylinders 53. Thereafter, the temperatures of the block 2 and sleeves 1 
are equilibrated at 97 whereby the sleeves 1 are frictionally retained in 
the overbored cylinders 53 of the engine block 2. The remanufactured block 
2 may then be assembled with other engine components, such as pistons 98 
with piston rings 10. 
The sleeves or replacement cylinders 1 are cold shrunk to a temperature 
which will contract their outer diameters to less than the diameter of the 
overbored cylinders 53. A temperature in a range of about 0.degree. F. to 
about -50.degree. F. (about -18.degree. C. to about -46.degree. C.) is 
appropriate for the required contraction. Such temperatures are below that 
which can be achieved by the more common refrigeration processes, whereby 
somewhat specialized refrigeration equipment or mildly cryogenic liquids 
might be required. It is important that the cylinders 1 are cooled and 
reheated as evenly as possible to avoid introducing stresses which might 
fatigue the metal from which the cylinders 1 are formed. In particular, 
handling of the cold shrunk cylinders 1 for insertion in the engine block 
2 should be done with similarly cooled handling tools (not shown). It is 
also important that the block cylinders 53 be bored at 94 with a high 
degree of accuracy since any irregularities of the overbored block 
cylinders 53 will be transferred to the replacement sleeves 1 when 
temperature equilibration causes the sleeves 1 to expand into frictional 
contact with the block cylinders 53. 
FIG. 12 illustrates the remanufacture of an aluminum block 101 having cast 
iron liners 102 using the restoration sleeves 1 of the present invention. 
The liners 102 were installed in an interference fit within the block 101 
when the block was originally manufactured. FIG. 13 illustrates an 
adhesive method 105 for restoring the block 102 using prefinished 
restoration sleeves 1. At 106, the sleeves 1 are supported, as by the 
boring fixture 15 or the honing fixture 28, and the sleeves 1 are bored at 
107 and honed at 108. At 109, the cylinder liners 102 are bored to achieve 
a non-interference fit with the sleeves 1. At 110, an adhesive is applied 
to the bored liners 102 and sleeves 1, and the sleeves 1 are inserted into 
the bored liners 102 at 111. Finally, the adhesive is cured at 112 to 
retain the sleeves 1 within the liners 102. 
FIG. 14 illustrates an alternative cold shrink method 115 of restoring the 
liners 102 of the aluminum block 101 using prefinished restoration sleeves 
1. The sleeves 1 are supported at 116, bored at 117, and honed at 118. At 
119, the liners 102 are bored. The prefinished sleeves 1 are cold shrunk 
at 120, and inserted into the bored liners 102 at 121. At 122, the 
temperatures of the block 101, liners 102, and sleeves 1 are equilibrated 
to retain the sleeves 1 within the liners 102 in an interference fit 
within the liners 102. 
FIG. 15 illustrates an adhesive method 130 for restoring engines using 
semifinished sleeves 1 and using ultraviolet inspection of the adhesive 
for complete coverage. The method 130 applies to both the cast iron block 
2 and the aluminum block 101, and the term cylinder structures is intended 
to encompass the block cylinders 53 of the block 2 and the cylinder liners 
102 of the block 101. At 131, the sleeves 1 are supported, as by the 
boring fixture 15, and bored at 132. The outer cylindrical surface 4 of 
the sleeves 1 is finished at 133 to bring the radial uniformity to within 
about 0.0005 inch, preferably using a centerless grinding process (not 
shown) which is well known in the machining arts. At 134, the cylinder 
structures of the block 2 or the block 101 are bored for a 
non-interference of the sleeves 1 therein. At 135, adhesive with an 
ultraviolet fluorescent dye is applied to the rebored cylinder structures 
and the sleeves 1. At 136, the applied adhesive is inspected using 
ultraviolet light. If gaps are observed where the adhesive was not 
applied, the gaps are touched up at 137, or the adhesive is simply 
reapplied. After the integrity of the adhesive is assured, the sleeves 1 
are inserted into the bored cylinder structures at 138, and the adhesive 
is allowed to cure at 139. After the adhesive has cured, the installed 
sleeve 1 may be honed to final dimensions and a final finish. 
It is to be understood that while certain forms of the present invention 
have been illustrated and described herein, it is not to be limited to the 
specific forms or arrangement of parts described and shown.