Abstract:
An inexpensive method for repairing a damaged spark plug hole of a cylinder engine includes drilling the damaged spark plug hole using a drill bit, tapping the drilled spark plug hole, threading a steel insert into the threaded hole and making a spark plug seat. The depth of the drilling, tapping and threading is limited by a stopper. A set of new tools are used to realize the foregoing process. All these procedures can be done while the cylinder having the damaged spark plug hole on the vehicle. The resulting hole is stronger and more durable than the original spark plug hole in the aluminum cylinder head.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Inquires have increased recently for repairing a damaged spark plug hole in an aluminum cylinder head of a vehicle engine. Most of the engines experiencing the problem have more than 80,000 miles on the vehicle. When the spark plug is removed in these high mileage engines for a tune-up the threads in the head may strip out as the plug is removed. This is due to carbon built up on the spark-plug threads.  
           [0002]    In the past, there was no way of repairing the damaged spark plug hole. Therefore, the cylinder head had to be replaced if the spark plug hole was damaged. The cost of labor and total materials used for the head replacement can be more than two thousand dollars. It is very expensive and time consuming.  
           [0003]    The present invention is directed to overcoming one or more of the above problems.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with the invention a new method is provided using new tools for repairing a damaged spark plug hole in a cylinder head of a vehicle engine. More specially, the repairing method uses a set of tools that would repair the damaged spark plug hole while the cylinder head having the damaged spark hole remains in the vehicle.  
           [0005]    Additionally, a new structure of a spark plug hole is provided that is harder to damage and can be used for much longer time compared with the original spark plug hole.  
           [0006]    An exemplary embodiment of the invention achieves the foregoing in a method including first drilling the damaged spark plug hole using a drill bit to provide a drilled hole. A stopper is used to limit the depth of the drill to prevent damaging a piston in a cylinder of the vehicle engine. Secondly, the drilled spark plug hole is tapped to provide a threaded hole with the stopper limiting the depth of the thread. Thirdly, a steel insert is threaded into the threaded hole with the stopper guiding the insert to a required depth. The insert is cylindrical having an outer threaded surface and an inner surface having a threaded portion. Finally, the insert is seated to make a spark plug seat.  
           [0007]    In accordance with one aspect of the invention, a tapping and threading tool is used for tapping the drilled hole and threading the insert into the threaded hole.  
           [0008]    In accordance with another aspect of the invention, a seating tool is used for seating the spark plug hole.  
           [0009]    As a result of the foregoing repairing method, the damaged spark plug hole is repaired using much less labor hours and materials compared with the replacement of the cylinder head. The amount of money saved by this method compared with the head replacement is substantial.  
           [0010]    The resulting repaired hole having a steel insert is stronger and more durable than the original spark plug hole in an aluminum cylinder head. 
       
    
    
       [0011]    Other features and advantages will become apparent from the following specification taken in conjunction with the accompanying drawings.  
       DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a sectional view of a damage spark plug hole in a cylinder head of a vehicle engine;  
         [0013]    [0013]FIG. 2 is a plane view of a stopper in accordance to the invention;  
         [0014]    [0014]FIG. 3 is a plane view of a drilling adapter with a drill bit in accordance to the invention;  
         [0015]    [0015]FIG. 4 is a plane view of a tapping and threading tool in accordance to the invention;  
         [0016]    [0016]FIG. 5 is a plane view of an insert in accordance to the invention;  
         [0017]    [0017]FIG. 6 is a plane view of a seating tool in accordance to the invention; and  
         [0018]    [0018]FIG. 7 is an enlarged, exploded fragmentary view of the repaired spark plug hole in accordance to the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    An exemplary embodiment of a set of tools for repairing a damaged spark plug hole  2  (shown in FIG. 1) in a cylinder head  4  of a vehicle engine is illustrated in FIGS.  2 - 5 .  
         [0020]    Referring to FIG. 2, a stopper  6  is cylindrical having a bevel  8  with a small protruding ear  10  at one end and a horizontal surface  11  at another end. A cylindrical opening  12  extends through the stopper  6 . The protruding ear  10  may be used as a handle.  
         [0021]    Referring now to FIG. 3, a drilling adapter  14  includes a shaft  16  having one end with an opening  17  receiving a drill bit  18  and another end connected to a short cylindrical block  19 . A screw  20  fastens the drill bit  18  to the shaft  16 . The short cylindrical block  20  has an opening  21  in which a rachet tool can fit. A shaft collar  22  is fixed around the shaft  16  at a selected place through screws  23 .  
         [0022]    A tapping and threading tool  24  is shown in FIG. 4. The tapping and threading tool  24  includes a shaft  26  having one end with an opening  27  receiving a modified cutter  28  and another end connected to a short cylindrical block  30 . A screw  31  fastens the modified cutter  28  to the shaft  26 . The modified cutter  28  has a wide threaded portion  32  proximate to the shaft  26  and a narrow distal threaded portion  34 . The short cylindrical block  30  has an opening  36  in which a rachet tool can fit. There is a slip collar  38  that can slide up and down on the shaft  26  by loosening Allen screws  39  or the like. The slip collar  38  has two positions  40 ,  42  that can be obtained by fastening the screws  39 . The tapping and threading tool  24  serves as a tapping tool when the slip collar  38  is secured at the first position  40  and a threading tool when the slip collar  38  is secured at the second position  42 .  
         [0023]    Referring to FIG. 5, a seating tool  44  includes a wide shaft  46 , used as a handle, having one end with an opening  47  receiving a seating adapter  48  and another end connected to a head  49 . A screw  50  fastens the seating adapter  48  to the shaft  46 . The seating adapter  48  is generally cylindrical and has a wide near end, received in the opening  47 , connected by a wide conical portion  54  to a narrow conical portion  56 . The narrow conical portion  56  is connected at other end to a central portion  58 . The central portion  58  is connected at a shoulder to a narrow distal end  60 .  
         [0024]    A steel insert  62  is shown in FIG. 6. The insert  62  is cylindrical having an outer threaded surface  64  and an inner surface  66  having a threaded portion  68  at one end and a smooth portion  70  at the other end.  
         [0025]    The above described tools of FIGS.  2 - 5  can be used to simply and inexpensively repair the damaged spark plug hole of FIG. 1.  
         [0026]    Before repairing the damaged spark hole  2  shown in FIG. 1, the battery source should be disconnected from a vehicle. With the old spark plug removed the engine is rotated from the front crankshaft pulley until the piston begins to go down to provide enough work space for repairing the hole  2 .  
         [0027]    The repairing method first includes placing the stopper  6  on the cylinder head  4  and over the damaged spark plug hole  2  to be repaired. The bevel  8  of the stopper  6  lies facing down against the cylinder head  4 . The drill bit  18  is sprayed heavily with a compound that allows some of the aluminum shavings to adhere to the drill bit  18  as it drills. The compound can be removed later when the drill bit  18  is removed. The compound may be, for example, Napa Tack Gasket. The drilling adapter  14  having the drill bit  18  is inserted through the opening  12  of the stopper  6  into the damaged spark plug hole  2 . A rachet tool is inserted onto the opening  21  at the end of the drilling adapter  14  and turned until the drill bit  18  penetrates and completes drilling of the hole  2  and the drilling adapter  14  with its shaft collar  22  turns freely against the horizontal surface  11  of the stopper  6 . The stopper  6  will not allow the drilling adapter  14  to enter the cylinder more than required. Then, the drilling adapter  14  is removed from the drilled hole.  
         [0028]    The repairing method second includes positioning the slip collar  38  on the tapping and threading tool  24  in the first position  40  and securing it. With the stopper  6  still positioned over the drilled spark plug hole, the tapping and threading tool  24  is inserted through the opening  12  of the stopper  6  into the hole. The stopper  6  is not only a stop for the drilling adapter  14 , but is also a depth gage for the tapping and threading tool  24 . A rachet tool is inserted onto the opening  36  at the end of the tapping and threading tool  24  and turned until the slip collar  38  is snug with the horizontal surface  11  of the stopper  6 . The wide threaded portion  32  of the modified cutter  28  completes tapping of the hole. The tapping and threading tool  24  is then removed.  
         [0029]    During the process of drilling and tapping the hole, there may be some aluminum shavings enter the cylinder. Therefore, the cylinder may be cleaned after the hole is drilled and tapped. For example, a cloth sock is wrapped over a flexible shaft-shaped cleaner tool and secured. The cloth sock is sprayed with the compound like Napa Tack Gasket. The shaft-shaped cleaner tool having the cloth sock is inserted through the drilled and tapped hole to enter the cylinder where the shavings are located. The shaft-shaped cleaner tool is rotated. The shavings stick to the cloth sock when the shaft-shaped cleaner tool is rotated. Then, the shaft-shaped cleaner tool is pulled out from the hole. A clean cloth is used to wipe the shavings from the cloth sock. This procedure is repeated until all the shavings are removed.  
         [0030]    Once the debris is removed from the cylinder, the repairing method thirdly includes installing the steel insert  62  onto the narrow threaded portion  34  of the modified cutter  28  of the tapping and threading tool  24 . The insert  62  is finger tightened into place. A clean solution is used to clean the outside threads of the insert  62 . Once cleaned, a locking compound, for example, Lock Tight 640, can be put on a plurality of threads to the center of the insert  62 . The slip collar  38  on the tapping and threading tool  24  is now slipped in the second position  42  and secured. The tapping and threading tool  24  with the insert  62  on the narrow threaded portion  34  of the modified cutter  28  is inserted through the opening  12  of the stopper  6  into the drilled and tapped spark plug hole. At this time the tapping and threading tool  24  is turned by hand until against the stopper  6 . A rachet tool is inserted onto the opening  36  at the end of the tapping and threading tool  24  and turned until the slip collar  38  is snug only against the horizontal surface  11  of the stopper  6 . This positions the insert  62 . With the locking compound, the insert  62  adheres to the threaded wall of the cylinder head  4 . The tapping and threading tool  24  is then unscrewed and removed by using hand pressure. The stopper  6  is also removed at this time.  
         [0031]    Finally, the repairing method includes inserting the seating tool  44  in the hole. The seating tool  44  is allowed to position itself in the insert  62 . A small hammer is used to tap the end of the seating tool  44  until feeling secure and bottoming out. The narrow distal end  60  of the seating adapter  48  aligns itself in and with the threaded portion  68  of the inner surface  66  of the insert  62 . The central portion  58  of the seating adapter  48  aligns itself in the smooth portion  70  of the inner surface  66  of the insert  62 . When the seating tool  44  is knocked in, the narrow conical portion  56  of the seating adapter  48  forces the outer surface  64  of the insert  62  out into the threaded wall of the cylinder head  4 . This allows a lock of the insert  62 . The wide conical portion  54  of the seating adapter  48  makes a spark plug seat when the seating tool  44  is knocked inward. All these steps are done at the same time as the seating tool  44  is struck. This procedure ensures total and complete alignment when the spark plug is installed. Then the seating tool  44  is removed.  
         [0032]    As shown in FIG. 7, the repaired spark plug hole includes a cylinder head  4  having a through cylindrical opening  72 . The opening  72  has a threaded portion  74  from a near end  76  of the opening  72 . The length of the threaded portion  76  of the opening  72  is less than that of the opening  72  itself. The metal insert  62  threaded in the threaded portion  74  of the opening  72  is cylindrical having a near end  78  and a far end  80 . The length of the threaded outer surface  64  of the insert  62  is at most equaling to that of the threaded portion  74  of the opening  72 . The inner surface  66  of the insert  62  has a threaded portion  68  proximate to the far end  80  of the insert  62 . There is a conical seat  80  in the inner surface  66  at the near end of the insert  62  formed using the tapping and threading tool of FIG. 4 as described above.  
         [0033]    The spark plug hole is now back to standard. Then a new spark plug can be installed.