Abstract:
The present invention provides a cartridge thermostat system that permits removal and replacement of the thermostat without removing the housing or coolant manifold. In the cartridge thermostat system, a coolant manifold is mounted on a cylinder head of an engine. The cylinder head has an engine by-pass and a coolant port for receiving a pilot on the coolant manifold. The coolant manifold further comprises at least one thermostat port with an associated cartridge thermostat and at least one passage for appropriate coolant flow. The cartridge thermostat fastens to the thermostat port and operatively positions a plug to an engine by-pass and a sleeve to a coolant passage. A wax plug in the cartridge thermostat expands when the coolant is hot and thereby appropriately and simultaneously positions the plug relative to the engine by-pass and the sleeve relative to the coolant passage.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to thermostats for engine cooling systems. More particularly, this invention relates to cartridge thermostats with a housing that forms part of the cooling system for an internal combustion engine.  
         BACKGROUND OF THE INVENTION  
         [0002]    Internal combustion engines have cooling systems to prevent the engine from overheating. FIG. 1 shows a typical cooling system from the prior art. As illustrated, a water pump in the front cover pumps coolant through passageways surrounding the cylinder sleeves in the engine. The coolant flows through the cylinder head before entering a by-pass passage for return to the water pump. At the cylinder sleeves, a portion of the coolant is diverted to pass through the oil cooler before returning to the water pump.  
           [0003]    A thermostat is positioned in the coolant passageway at the entrance of the by-pass in the cylinder head. The thermostat opens and closes depending upon the coolant temperature. When the coolant temperature rises above a particular temperature, the thermostat closes the by-pass passage and opens the radiator passage to divert coolant to the radiator. The coolant passes through the radiator before returning to the water pump.  
           [0004]    In many internal combustion engines, the thermostat is positioned inside a thermostat housing. FIG. 2 shows this arrangement according to the prior art. A hose connects the thermostat housing to the radiator. The housing separates the radiator hose from the engine, thus making it easier to remove the radiator hose. While maintenance of the radiator and hoses is easier, the thermostat housing does not reduce the difficulties of replacing a thermostat.  
           [0005]    To replace the thermostat, the housing must be removed. While it is routine to remove the bolts securing the housing to the engine, it is rather difficult to get to the housing. In many engines, the housing is located beneath or is obstructed by auxiliary equipment and other engine parts. These equipment and parts must be removed before there is sufficient access to remove the thermostat housing.  
           [0006]    Moving the auxiliary equipment and engine parts increases the time and cost of replacing the thermostat. It also is a deterrent to replacing the thermostat as part of routine or preventative maintenance of the engine. This leads to overheating and breakdowns of the engine while it is in service.  
           [0007]    Accordingly, there is a need for a thermostat which may be replaced with out removing the thermostat housing.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a cartridge thermostat system that permits removal and replacement of the thermostat without removing the housing or coolant manifold. In the cartridge thermostat system, a coolant manifold is mounted on a cylinder head of an engine. The cylinder head has an engine by-pass and a coolant port for receiving a pilot on the coolant manifold.  
           [0009]    In a first embodiment, the coolant manifold has a thermostat port and a radiator passage. A cartridge thermostat screws into the thermostat port and operatively positions a plug adjacent to the engine by-pass. A wax plug in the cartridge thermostat expands when the coolant is hot to move the plug against the engine by-pass.  
           [0010]    In a second embodiment, the cartridge thermostat operatively positions a plug adjacent to an engine by-pass and operatively positions a sleeve adjacent to a radiator passage. The plug and sleeve are connected to move together along a shaft on the cartridge thermostat. A wax plug expands when the coolant temperature increases, thus moving the plug and sleeve.  
           [0011]    When the engine is cold the sleeve blocks the radiator passage. The engine by-pass is open permitting coolant to flow through the engine by-pass. When the engine is hot the wax plug moves the plug to close the engine by-pass. Coolant stops flowing through the engine by-pass. At the same time, the wax plug also moves the sleeve to open the radiator passage. Coolant flows through sleeve holes in the sleeve and through the radiator passage to the radiator.  
           [0012]    In a third embodiment, the coolant manifold has a manifold by-pass and a radiator passage. The wax plug moves the sleeve to open and close the manifold by-pass and the radiator passage as the coolant temperature increases and decrease. The plug seals the engine by-pass.  
           [0013]    In a fourth embodiment, the coolant manifold has two thermostat ports. This enables the same coolant manifold to be used on two engine configurations. The thermostat ports are connected by a coolant passage. The second thermostat port is connected independently to a manifold by-pass and a radiator passage.  
           [0014]    In the first engine configuration, a cartridge plug extends through the first thermostat port. The cartridge plug seals the engine by-pass preventing coolant from flowing into the engine by-pass. A cartridge thermostat extends through the second thermostat port. The cartridge thermostat operatively positions a sleeve adjacent to the manifold by-pass and the radiator passage.  
           [0015]    When the engine is cold, the sleeve blocks the radiator passage preventing coolant from circulating through the radiator. Coolant passes through the first thermostat port, through the coolant passage, through the second thermostat port, through sleeve holes in the sleeve, and through the manifold by-pass.  
           [0016]    When the engine is hot, a wax plug in the cartridge thermostat expands and moves the sleeve to open the radiator passage and to block the manifold by-pass. Coolant passes through the first thermostat port, through the coolant passage, through the second thermostat port, and through the radiator passage to the radiator.  
           [0017]    In the second engine configuration, a cartridge thermostat extends through the first thermostat port. The cartridge thermostat operatively positions a sleeve adjacent to the coolant passage. The cartridge thermostat also operatively positions the plug adjacent to the engine by-pass. The cartridge thermostat has a wax plug which expands when the coolant is hot. The wax plug moves the sleeve and plug together. A cartridge cap extends into the second thermostat port. The cartridge cap seals the second thermostat port. A manifold plug blocks the flow of coolant out of the manifold by-pass.  
           [0018]    When the engine is cold, the sleeve blocks the coolant passage preventing coolant from circulating through the radiator. The plug is open permitting coolant to flow through the engine by-pass.  
           [0019]    When the engine is hot, a wax plug in the cartridge thermostat expands and moves the sleeve to open the coolant passage. At the same time, the wax plug moves the plug to seal the engine by-pass. Coolant passes through the first thermostat port, through sleeve holes, through the coolant passage, through the second thermostat port, and through the radiator passage to the radiator.  
           [0020]    As described, a wax plug is used to move the sleeve and/or plug in these embodiments. However, an electric or other operating means for a thermostat may be used to increase the stroke length of the thermostat. In addition, the diaphragm in the thermostat may be altered to also increase the stroke length. An optional air bleed system may be incorporated into the cap of the cartridge thermostat.  
           [0021]    The following drawings and description set forth additional advantages and benefits of the invention. More advantages and benefits are obvious from the description and may be learned by practice of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The present invention may be better understood when read in connection with the accompanying drawings, of which:  
         [0023]    [0023]FIG. 1 shows a perspective view of a cooling system for an internal combustion engine according to the prior art;  
         [0024]    [0024]FIG. 2 shows a cross-sectional side view of a cooling manifold with a thermostat according to the prior art;  
         [0025]    [0025]FIG. 3 shows a cross-sectional side view of a cartridge thermostat system according to the first embodiment of the present invention;  
         [0026]    [0026]FIG. 4 shows a cross-sectional side view of an extension assembly for a cartridge thermostat when the engine is cold according to the present invention;  
         [0027]    [0027]FIG. 5 shows a cross-sectional side view of an extension assembly for a cartridge thermostat when the engine is hot according to the present invention;  
         [0028]    [0028]FIG. 6 shows a cross-sectional side view of an extension assembly for a cartridge thermostat using an alternate diaphragm design according to the present invention;  
         [0029]    [0029]FIG. 7 shows a cross-sectional side view of a cartridge thermostat having an electronic thermostat according to the present invention;  
         [0030]    [0030]FIG. 8 shows a cross-sectional side view of a cartridge thermostat system when the engine is cold according to the second embodiment of the present invention;  
         [0031]    [0031]FIG. 9 shows a cross-sectional side view of a cartridge thermostat system when the engine is hot according to the second embodiment of the present invention;  
         [0032]    [0032]FIG. 10 shows a cross-sectional side view of a cartridge thermostat system when the engine is cold according to the third embodiment of the present invention;  
         [0033]    [0033]FIG. 11 shows a cross-sectional side view of a cartridge thermostat system when the engine is hot according to the third embodiment of the present invention;  
         [0034]    [0034]FIG. 12 shows an external perspective view of a coolant manifold for the cartridge thermostat system of the present invention;  
         [0035]    [0035]FIG. 13 shows an internal perspective view of a coolant manifold for the cartridge thermostat system of the present invention;  
         [0036]    [0036]FIG. 14 shows a cross-sectional side view of a cartridge thermostat system when a first engine configuration is cold according to the fourth embodiment of the present invention;  
         [0037]    [0037]FIG. 15 shows a cross-sectional side view of a cartridge thermostat system when a first engine configuration is hot according to the fourth embodiment of the present invention;  
         [0038]    [0038]FIG. 16 shows a cross-sectional side view of a cartridge thermostat system when a second engine configuration is cold according to the fourth embodiment of the present invention;  
         [0039]    [0039]FIG. 17 shows a cross-sectional side view of a cartridge thermostat system when a second engine configuration is hot according to the fourth embodiment of the present invention;  
         [0040]    [0040]FIG. 18 shows a top perspective view of a coolant manifold for the cartridge thermostat system according to the fourth embodiment of the present invention;  
         [0041]    [0041]FIG. 19 shows a side perspective view of a coolant manifold for the cartridge thermostat system according to the fourth embodiment of the present invention; and  
         [0042]    [0042]FIG. 20 shows a front perspective view of a coolant manifold for the cartridge thermostat system according to the fourth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0043]    [0043]FIG. 3 shows a first embodiment of a cartridge thermostat system  100  according to the present invention. A coolant manifold  105  is mounted on a cylinder head  110  of an engine (not shown). The coolant manifold  105  forms a radiator passageway  170  for circulating coolant to the radiator (not shown). The cylinder head  110  has an engine by-pass  165  for circulating coolant to the engine. The coolant manifold  105  also has a pilot  115 , which inserts into a coolant port  120  formed by the cylinder head  110 . A manifold o-ring  125  extends around the pilot  115  at its interface with the coolant port  120  for sealing the connection of the coolant manifold  105  with the cylinder head  110 .  
         [0044]    A cartridge thermostat  130  extends through a thermostat port  175  formed by the coolant manifold  105 . The cartridge thermostat  130  has a cap  135 , a threaded portion  145 , a shaft  150 , and a plug  155 . A wax plug is hidden from view inside the cartridge thermostat  130 . The wax plug expands and contracts upon heating and cooling to actuate the shaft  150 .  
         [0045]    The threaded portion  145  is configured for engaging a similarly threaded portion of the coolant manifold  105  along the thermostat port  175 . A thermostat o-ring  160  surrounds the cartridge  140  adjacent to the connection of the threaded portion to the cap  135 .  
         [0046]    To install the cartridge thermostat  130 , it is inserted into the coolant manifold  105  and screwed into place. The thermostat o-ring  160  engages the coolant manifold  105  thus sealing the thermostat port  175 . The shaft  150  extends through the coolant manifold  105  and the pilot  115 , placing the plug  155  in an operating position adjacent to the engine by-pass  165 . The plug  155  and shaft  150  may include a spring (not shown) or other elastomeric device to compensate for their expansion when the coolant is hot. To remove the cartidge thermostat  130 , it is simply unscrewed from the coolant manifold  105 .  
         [0047]    When the engine is cold, the plug  155  is inside the pilot  115 , thus blocking the flow of coolant to the radiator passage  170 . The engine by-pass  165  is open, permitting coolant to circulate through the engine.  
         [0048]    As the engine temperature increases, the coolant temperature also rises. The wax plug expands inside the cartridge thermostat  130 . At a certain temperature or predetermined value, usually 190° F., the wax plug actuates the shaft  150  to move the plug  155  against the engine by-pass  165 . In this position, the plug  155  stops the flow of coolant through the engine by-pass  165 . The coolant flows through the pilot  115 , into the radiator passage  170 , and then into the radiator.  
         [0049]    [0049]FIG. 4 shows an extension assembly  400  of the cartridge thermostat  130  according to the present invention. Extension assembly  400  includes a diaphragm  410  operatively positioned adjacent to a wax plug  415  inside an extension housing  420 . The shaft  150  is connected to the diaphragm  410 . The extension assembly  400  is sealed. As shown, the extension assembly  400  may be integrated with and configured to form the plug  155 . Alternatively, the extension assembly  400  may be positioned along the shaft  150  in any position as long as it senses the temperature of the coolant. In these alternated configurations, the shaft may incorporate a spring or other elastomeric device to avoid the effect of too much extension against the engine by-pass  165 .  
         [0050]    As the coolant temperature increases, the wax plug  415  expands as shown in FIG. 5. The expansion of the wax plug  415  moves the plug  155  the distance of its stroke length, l, which is on the order of 0.5 in. The plug  155  closes the engine by-pass  165 , thus stopping the flow of coolant to the engine by-pass  165 . Since the plug  155  no longer blocks the pilot  115 , coolant flows freely into the radiator passage  170 . Once the plug  155  stops against the engine by-pass  165 , the wax plug  415  will expand along the center portion of the expansion assembly  400  to avoid over flexing the shaft  150 .  
         [0051]    [0051]FIG. 6 shows an alternative extension assembly  600  of the cartridge thermostat  130  according to the present invention. The extension assembly  600  includes a diaphragm  610  operatively positioned adjacent to a wax plug  615  inside an extension housing  620 . The diaphragm  610  has a thicker middle section as shown. The shaft  150  is connected to the diaphragm  610 , adjacent to the thicker middle section. The extension assembly  600  is sealed and is configured to form the plug  155 .  
         [0052]    When the coolant temperature rises, the wax plug  615  expands against the diaphragm  610  moving the plug  155  against the engine by-pass  165 . The thicker middle section of the diaphragm  610  increases the stroke length when the wax plug  615  expands.  
         [0053]    [0053]FIG. 7 shows the upper portion of an electronic cartridge thermostat  730  according to the present invention. The cartridge thermostat  130  may be an electronic thermostat  730  even though the extension assembly  400  is described using a wax plug  415 ,  615 . The electronic thermostat  730  may be any commercially available thermostat configured for the cartridge thermostat system including an electronically-controlled value or similar mechanism. The lower portion is not shown and would include the electronically-controlled valve or similar device. With the electronic thermostat  730 , the shaft  150  connects to an electronically-controlled plug  155  (not shown) or other control valve.  
         [0054]    The electronic cartridge thermostat  730  has a cap  735  and a threaded portion  745 . Terminals and wiring passages  755 ,  765  extend through the cap  735 , and the threaded portion  1145 . The terminals and wire passages  755 ,  765  permit wires for to pass through the cap  735  to the electronically-controlled valve or similar device.  
         [0055]    An optional air bleed mechanism  760  also extends through the cap  735  and the threaded portion  745 . The air bleed mechanism allows any air “trapped” in the coolant system to escape. The air bleed mechanism  760  replaces or works with an air bleed mechanism on the coolant manifold (not shown). The air bleed mechanism  760  may be used in the cartridge thermostats  130  using a wax plug.  
         [0056]    [0056]FIG. 8 shows a second embodiment of a cartridge thermostat system  800  according to the present invention. Similar to the first embodiment, a coolant manifold  805  is mounted on a cylinder head  810  of an engine (not shown). The coolant manifold  805  forms a radiator passageway  870  for circulating coolant through the radiator (not shown). The radiator passageway has an inside diameter or height, h.  
         [0057]    The cylinder head  810  has an engine by-pass  865  for circulating coolant through the engine. The coolant manifold  805  also has a pilot  815 , which inserts into a coolant port  820  formed by the cylinder head  810 . A manifold o-ring  825  extends around the pilot  815  at its interface with the coolant port  820  for sealing the coolant manifold  805  to the cylinder head  810 .  
         [0058]    A cartridge thermostat  830  extends through a thermostat port  875  formed by the coolant manifold  805 . The cartridge thermostat  830  has a cap  835 , a shaft  850 , a plug  855 , and a sleeve  807 . A wax plug is hidden from view inside the cartridge thermostat  830 . The wax plug expands and contracts upon heating and cooling to actuate the plug  855 . A thermostat o-ring  860  surrounds the threaded portion  845  adjacent to the cap  835 .  
         [0059]    The sleeve  807  is configured to have outside dimensions substantially the same as the inside dimensions of the pilot  815 . The sleeve  807  also has larger height than h, the height or inside diameter of the radiator passageway  870 . As shown, both the sleeve  807  and the pilot  815  have a cylindrical shape. Other shapes may be used. The sleeve  807  has sleeve holes  815  for coolant to flow through the inside of the sleeve  807 .  
         [0060]    The sleeve  807  is mounted on the cartridge thermostat  830  to move along the shaft  850  as the plug  855  moves. The mounting may be done using a co-axial tube (not shown), coaxial to the shaft  850  and connecting the sleeve  807  to the plug  855 . Alternatively, supporting rods (not shown) may be used to connected and position the sleeve  807  above the plug  855 . Other mounting methods may be used.  
         [0061]    To install the cartridge thermostat  830 , it is aligned and screwed into place. The thermostat o-ring  860  engages the coolant manifold  805  thus sealing the thermostat port  875 . The shaft  850  extends through the coolant manifold  805  and into the pilot  815 . The shaft  850  places the plug  855  in an operating position adjacent to the engine by-pass  865 . The shaft  850  also positions the sleeve  807  in an operating position adjacent to the radiator passage  870 . The plug  855  and shaft  850  may include a spring (not shown) or other elastomeric device to compensate for their expansion when the coolant is hot. To remove the cartridge thermostat  830 , it is simply unscrewed from the coolant manifold  105 .  
         [0062]    The sleeve  807  is designed to operate in conjunction with the radiator passage  870  once the cartridge thermostat  830  is installed. The sleeve  807  is slightly larger than h, the height or inside diameter of the radiator passage  870 , thus preventing coolant from flowing into the radiator passage  870  when the sleeve  807  blocks the radiator passage  870 .  
         [0063]    When the engine is cold, the sleeve  807  blocks the radiator passage  870  as shown in FIG. 8. The position of the sleeve  807  prevents coolant from flowing though the radiator passage  870  to the radiator. The engine by-pass  865  is open, permitting coolant to circulate through the engine.  
         [0064]    As the engine temperature increases, the coolant temperature also rises. The wax plug expands inside the cartridge thermostat  830 . At a certain temperature or predetermined value, usually 190° F., the wax plug moves the plug  855  against the opening for the engine by-pass  865 . The movement of the plug  855  also moves the sleeve  807  to open the radiator passage  870  as shown in FIG. 9. As a result, the coolant stops flowing through the engine by-pass  865 . The coolant flows through the sleeve holes  815  and into the radiator passage  870 , and then into the radiator.  
         [0065]    [0065]FIG. 10 shows a third embodiment of a cartridge thermostat system  900  according to the present invention. Similar to the first embodiment, a coolant manifold  905  is mounted on a cylinder head  910  of an engine (not shown). The coolant manifold  905  forms a manifold by-pass  980  and a radiator passageway  970  for circulating coolant through the radiator (not show). The manifold by-pass  980  has an inside diameter or height, H 1 . The radiator passage  970  has and inside diameter or height, H 2 . H 1  and H 2  may be the same height or different heights. The cylinder head  910  has an engine by-pass  965 . The coolant manifold  905  also has a pilot  915 , which inserts into a coolant port  920  formed by the cylinder head  910 . A manifold o-ring  925  extends around the pilot  915  at its interface with the coolant port  920  for sealing the coolant manifold  905  to the cylinder head  910 .  
         [0066]    A cartridge thermostat  930  extends through a thermostat port  975  formed by the coolant manifold  905 . The cartridge thermostat  930  has a cap  935 , a threaded portion  945 , a shaft  950 , a plug  955 , and a sleeve  907 . A wax plug is hidden from view inside the cartridge thermostat  930 . The wax plug expands and contracts upon heating and cooling to actuate the sleeve  907 . The threaded portion  945  is configured to engage a similarly threaded portion of the coolant manifold  905  along the thermostat port  975 . A thermostat o-ring  960  surrounds the cartridge thermostat  930  adjacent to the cap  935 .  
         [0067]    The sleeve  907  is configured to have outside dimensions substantially the same as the inside dimensions of the pilot  915 . As shown, both the sleeve  907  and the pilot  915  have a cylindrical shape. Other shapes may be used. The sleeve  907  slides along the shaft  950 . The sleeve  907  has sleeve holes  915  for coolant to flow through the sleeve  907 . The height of the sleeve  907  is larger than either H 1  or H 2 .  
         [0068]    To install the cartridge thermostat  930 , it is aligned and screwed into place. The thermostat o-ring  960  engages the coolant manifold  905  thus sealing the thermostat port  975 . The shaft  950  extends through the coolant manifold  905  and into the pilot  915 . The shaft  950  is of such a length to place the plug  955  against the engine by-pass  965 , thus preventing coolant from flowing through it. The plug  955  and shaft  950  may have a spring (not shown) or other elastomeric device to compensate for their expansion when the coolant is hot. To remove the cartridge thermostat  930 , it is simply unscrewed from the coolant manifold  905 .  
         [0069]    The sleeve  907  is designed to operate in conjunction with the manifold by-pass  980  and the radiator passage  970  once the cartridge thermostat  930  is installed. The sleeve  907  has a slightly larger surface area than the manifold by-pass  980  and the radiator passage  970 . The sleeve  907  prevents coolant from flowing into the manifold by-pass  980  when the sleeve  907  blocks the manifold by-pass  980 . The sleeve  907  prevents coolant from flowing into the radiator passage  970  when the sleeve  907  blocks the radiator passage  970 .  
         [0070]    When the engine is cold, the sleeve  907  blocks the radiator passage  970  as shown in FIG. 10. The position of the sleeve  907  prevents coolant from flowing though the radiator passage  970  to the radiator. The coolant flows through the sleeve holes  915  into the manifold by-pass  980 .  
         [0071]    As the engine temperature increases, the coolant temperature also rises. The wax plug expands inside the cartridge thermostat  930 . At a certain temperature or predetermined value, usually 190° Fahrenheit, the wax plug moves the sleeve  907  to open the radiator passage  970  and to close the manifold by-pass  970  as shown in FIG. 11. The coolant cannot flow through the manifold by-pass  980 . The coolant flows through into the radiator passage  970  into the radiator.  
         [0072]    FIGS.  12 - 13  show exterior and interior views respectively of a coolant manifold  1205  for the present invention. The coolant manifold  1205  is mounted on a cylinder head  1200  of an engine (not shown) using mounting bolts  1225 . The coolant manifold  1205  is an iron or steel casting, but may be made from another material and using another fabrication method. The coolant manifold  1205  has a pilot  1215  for interfacing with the cylinder head  1200  and forms a thermostat port  1275 , which is threaded for receiving the threaded portion of a cartridge thermostat (not shown). The coolant manifold  1205  has a snout  1210  for connecting a radiator hose (not shown).  
         [0073]    FIGS.  14 - 17  show a fourth embodiment of a cartridge thermostat system  1400 ,  1600  according to the present invention. The fourth embodiment uses the same coolant manifold  1405  for different engine configurations.  
         [0074]    FIGS.  14 - 15  show a cartridge thermostat system  1400  for a first engine configuration. The coolant manifold  1405  is mounted on a cylinder head  1410  of the first engine (not shown). The cylinder head  1410  has an engine by-pass  1465 . The cylinder head  1410  forms a coolant port  1420  for receiving a pilot  1415  of the coolant manifold  1405 . A manifold o-ring  1425  extends around the pilot  1415  at its interface with the coolant port  1420  for sealing the coolant manifold  1405  to the cylinder head  1410 .  
         [0075]    The coolant manifold  1405  forms a first thermostat port  1475  interconnected by a coolant passage  1482  to a second thermostat port  1477 . The coolant manifold  1405  forms a radiator passage  1470  and a manifold by-pass  1480 , both connected independently to the second thermostat port  1477 . The radiator passage  1470  circulates coolant to the radiator (not shown). The radiator passage  1470  has an inside diameter or height, H 1 . The manifold by-pass  1480  circulates coolant to the engine (not shown). The manifold by-pass  1480  has an inside diameter or height, H 2 . H 1  and H 2  may be the same or different. While the coolant passage  1482 , the radiator passage  1470 , and the manifold by-pass  1480  are shown in the same plane, they may be radially disposed around the second thermostat port  1477 .  
         [0076]    For the first engine configuration, a cartridge plug  1430  extends through the first thermostat port  1475 . The cartridge plug  1430  has a cap  1435 , a threaded portion  1445 , a shaft  1450 , and a plug  1455 . A thermostat o-ring  1460  surrounds the threaded portion  1445  adjacent to the cap  1435 .  
         [0077]    To install the cartridge plug  1430 , it is aligned and screwed into place. The thermostat o-ring  1460  engages the coolant manifold  1405  thus sealing the first thermostat port  1475 . The shaft  1450  extends through the coolant manifold  1405  and the pilot  1415 . The shaft  1450  places the plug  1455  against the engine by-pass  1465 , thus blocking coolant from flowing through the engine by-pass  1465 . The plug  1455  and shaft  1450  may include a spring (not shown) or other elastomeric device to compensate for their expansion when the coolant is hot. To remove the cartridge plug  1430 , it is simply unscrewed from the coolant manifold  1405 .  
         [0078]    Additionally, a cartridge thermostat  1432  extends through the second thermostat port  1477 . The cartridge thermostat  1432  has a cap  1437 , a threaded portion  1477 , a shaft  1452 , and a sleeve  1407 . A wax plug is hidden from view inside the cartridge thermostat  1432 . The wax plug expands and contracts upon heating and cooling to actuate the sleeve  1407 . A thermostat o-ring  1462  surrounds the threaded portion  1447  adjacent to the cap  1435 .  
         [0079]    The sleeve  1407  is configured to have substantially the same outside dimensions as the inside dimensions of the second thermostat port  1477 . The sleeve  1407  also has larger height than either H 1 , the height of the radiator passageway  1470 , or H 2 , the height of the manifold by-pass  1480 . As shown, both the sleeve  1407  and the second thermostat port  1477  have a cylindrical shape. Other shapes may be used. The sleeve  1407  has sleeve holes  1417  for coolant to flow through the inside of the sleeve  1407 .  
         [0080]    The sleeve  1407  is mounted on the cartridge thermostat  1432  to move along the shaft  1450 . The mounting may be done using a co-axial tube (not shown). Alternatively, supporting rods (not shown) may be used to connect and position the sleeve  1407 . Other mounting methods may be used. Regardless of the mounting method, the sleeve  1407  is operatively connected to the hidden wax plug in the cartridge thermostat  1432 . The wax plug causes the sleeve  1407  to move along the shaft  1450 .  
         [0081]    To install the cartridge thermostat  1432 , it is aligned and screwed into place. The thermostat o-ring  1462  engages the coolant manifold  1405  thus sealing the second thermostat port  1477 . The shaft  1450  extends through the coolant manifold  1405  and positions the sleeve  1407  in an operating position adjacent to the radiator passage  1470  and the manifold by-pass  1480 . The shaft  1450  may have a spring (not shown) or other elastomeric device to compensate for its expansion when the coolant is hot. To remove the cartridge thermostat  1432 , it is simply unscrewed from the coolant manifold  1405 .  
         [0082]    The sleeve  1407  is designed to operate in conjunction with the radiator passage  1470  and the manifold by-pass  1480  once the cartridge thermostat  1432  is installed. The sleeve  1407  is slightly larger than the radiator passage  1470  and the manifold by-pass  1480 . When the engine is cold, the sleeve  1407  blocks the radiator passage  1470  as shown in FIG. 14. The position of the sleeve  1407  prevents coolant from flowing though the radiator passage  1470  to the radiator (not shown). The coolant flows through the sleeve holes  1417  into the manifold by-pass  1480  for circulation through the engine.  
         [0083]    As the engine temperature increases, the coolant temperature also rises. The wax plug expands inside the cartridge thermostat  1432 . At a certain temperature or predetermined value, usually 190° F., the wax plug moves the sleeve  1407  to open the radiator passage  1470  and close the manifold by-pass  1480  as shown in FIG. 15. As a result, the coolant stops flowing through the sleeve holes  1417  and the manifold by-pass  1480 . The coolant flows through the radiator passage  1470 , and then into the radiator.  
         [0084]    FIGS.  16 - 17  show a cartridge thermostat system  1600  for a second engine configuration. The coolant manifold  1405  is mounted on a cylinder head  1610  of the second engine (not shown). The cylinder head  1610  has an engine by-pass  1665 . The cylinder head  1610  forms a coolant port  1620  for receiving a pilot  1415  of the coolant manifold  1405 . A manifold o-ring  1425  extends around the pilot  1415  at its interface with the coolant port  1620  for sealing the coolant manifold  1405  to the cylinder head  1610 .  
         [0085]    The coolant manifold  1405  forms a first thermostat port  1475  interconnected by a coolant passage  1482  to a second thermostat port  1477 . Coolant passage  1482  has an inside diameter or height, H 3 . The coolant manifold  1405  also forms a radiator passage  1470  and a manifold by-pass  1480 , both connected independently to the second thermostat port  1477 . The radiator passage  1470  circulates coolant to the radiator (not shown). The radiator passage  1470  and coolant passage  1482  may have the same or different inside diameters or heights. While coolant passage  1482 , radiator passage  1470 , and manifold by-pass  1480  are shown in the same plane, they may be radially disposed around the second thermostat port  1477 .  
         [0086]    For the second engine configuration, a manifold plug  1690  stops the flow of coolant through the manifold by-pass  1480 . The manifold plug  1690  may be any variety of plugging device suitable to stop the flow of coolant. The manifold plug  1690  may be a cap design having a threaded portion for screwing onto the coolant manifold  1405  to close the exit of the manifold by-pass  1480 .  
         [0087]    A cartridge cap  1632  extends into the second thermostat port  1477 . The cartridge cap  1632  has a cap  1637  and a threaded portion  1647 . A thermostat o-ring  1662  surrounds the threaded portion  1647  adjacent to the cap  1637 . To install the cartridge cap  1632 , it is aligned and screwed into place. The thermostat o-ring  1662  engages the coolant manifold  1405  thus sealing the second thermostat port  1477 . To remove the cartridge cap  1632 , it is simply unscrewed from the coolant manifold  1405 .  
         [0088]    A cartridge thermostat  1630  extends through the first thermostat port  1475 . The cartridge thermostat  1630  has a cap  1635 , a threaded portion  1645 , a shaft  1650 , a sleeve  1607 , and a plug  1655 . A thermostat o-ring  1660  surrounds the threaded portion  1645  adjacent to the cap  1635 . A wax plug is hidden from view inside the cartridge thermostat  1630 . The wax plug expands and contracts upon heating and cooling to actuate the plug  1655 .  
         [0089]    To install the cartridge thermostat  1630 , it is aligned and screwed into place. The thermostat o-ring  1660  engages the coolant manifold  1405  thus sealing the first thermostat port  1475 . The shaft  1650  extends through the coolant manifold  1405  and the pilot  1415 , placing the plug  1655  in an operating position adjacent to the engine by-pass  1665 . The plug  1655  and shaft  1650  may include a spring (not shown) or other elastomeric device to compensate for their expansion when the coolant is hot. To remove the cartridge thermostat  1630 , it is simply unscrewed from the coolant manifold  1405 .  
         [0090]    The sleeve  1607  is configured to have substantially the same outside dimensions as the inside dimensions of the first thermostat port  1475 . The sleeve  1607  also has a larger height than H 3 , the height or inside diameter of the coolant passage  1482 . As shown, both the sleeve  1607  and the first thermostat port  1475  have a cylindrical shape. Other shapes may be used. The sleeve  1607  has sleeve holes  1617  for coolant to flow through the inside of the sleeve  1607 .  
         [0091]    The sleeve  1607  is mounted on the cartridge thermostat  1630  to move along the shaft  1650  as the plug  1655  moves. The mounting may be done using a co-axial tube (not shown) that is coaxial to the shaft  1652 . Alternatively, supporting rods (not shown) may be used to connect the sleeve  1607  to the plug  1655 . Other mounting methods may be used. Regardless of the mounting method, the sleeve  1607  is operatively connected to move as the plug  1655  moves in relation to the hidden wax plug.  
         [0092]    The sleeve  1607  is designed to operate in conjunction with the coolant passage  1482  once the cartridge thermostat  1430  is installed. The sleeve  1607  is slightly larger than the coolant passage  1482 . When the engine is cold, the sleeve  1407  blocks the coolant passage  1482  as shown in FIG. 16. The plug  1655  does not engage the engine by-pass  1665 . The position of the sleeve  1407  prevents coolant from flowing though the coolant passage  1482 . The position of the plug  1655  permits coolant to flow through the engine by-pass  1665  for circulation through the engine.  
         [0093]    As the engine temperature increases, the coolant temperature also rises. The wax plug expands inside the cartridge thermostat  1630  At a certain temperature or predetermined value, usually 190° F., the wax plug moves the sleeve  1607  to open the radiator passage  1470  as shown in FIG. 17. The wax plug also moves the plug  1655  to close the engine by-pass  1665 . As a result, the coolant stops flowing through the engine by-pass  1665 . The coolant flows through the sleeve holes  1417 , into the coolant passage  1482 , through the second thermostat port  1477 , and then through the radiator passage  1470  into the radiator.  
         [0094]    FIGS.  18 - 20  show various views of the coolant manifold  1405  according to the fourth embodiment of the present invention. FIG. 18 is a top view of the coolant manifold  1405  showing the first thermostat port  1475 , the second thermostat port  1477 , the manifold by-pass  1480 , the radiator passage  1470 , and the snout  1800  for connecting to a radiator hose (not shown).  
         [0095]    [0095]FIG. 19 is a side view of the coolant manifold  1405  showing the pilot  1415 , the first thermostat port  1475 , the second thermostat port  1477 , the manifold by-pass  1480 , the radiator passage  1470 , the coolant passage  1482 , and the snout  1800  for connecting to a radiator hose (not shown). The manifold by-pass  1480  has a plug extension  1490  for receiving the manifold plug  1690  (not shown). The first thermostat port  1475  has a different height than the second thermostat port  1477 .  
         [0096]    [0096]FIG. 20 is a front view of the coolant manifold  1405  showing the pilot  1415 , the first thermostat port  1475 , the second thermostat port  1477 , the manifold by-pass  1480 , the plug extension  1490 , the radiator passage  1470 , and the coolant passage  1482 . This view also shows the difference in height between the first thermostat port  1475  and the second thermostat port  1477 .  
         [0097]    While the invention has been described and illustrated, this description is by way of example only. Additional advantages will occur readily to those skilled in the art, who may make changes without departing from the true spirit and scope of the invention. Therefore, the invention is not limited to the specific details, representative devices, and illustrated examples in this description.