Overheating (maxs dash temp guage)
1994 Firebird Formula LT1 5.7L v8 (Fourth Generation F-Body)
Long story of bad mechanics (skip the next paragraph for my question).
After all the shops, this is what actually happened:
Developed a bad water line from the radiator to the thermostat. The spray flooded my optispark (car would not crank). Took to a local Firestone in Columbia, SC to replace the optispark to allow me to find the leak. Firestone found water in the weep hole on the bottom of the water pump and insisted that I had a bad water pump and convinced me to replace it. Firestone did not replace the “coupler, water pump driveshaft” so my new water pump never turned. Got two blocks and returned with bad overheating. Firestone claimed I had a blown head gasket. Replaced the top-half of my engine and same problem. Had a different mech pull the water pump and to my horror found the missing “coupler, water pump driveshaft” (Firestone claims the other mech must have lost it). I have replaced a large amount of the cooling system. Still overheats.
Diagnostics
The list of replaced new parts is – OptiSpark, Sparkplugs, Radiator, upper and lower radiator hoses, water pump, “coupler, water pump driveshaft” ($35 from dealer if you ever need one), thermostat (180 degree), radiator cap, Head gaskets (x2), Valve job, manifold gaskets, exhaust header gaskets (x2). Also jumped the OBD1 connector to force PCM into diagnostic mode and run both fans (they are good) then verified they came on correctly as the engine overheated (confirming the detection circuit).
Currently the engine is still overheating. Pulled the thermostat out and took the lower radiator hose off to see the that coolant flow “surges” out. This meaning that there is good flow with breaks of no flow. Expected to have constant flow like a garden hose.
Question: Still Overheating?
Back to the drawing board, I have been reading trying to find what else could be wrong (see the section below I found on the net). Discovering that the coolant system works nothing like how I thought it did, I am going to drain the system again and hope I have a weird air pocket causing my grief.
Does anyone have any other suggestions? I am out of ideas and hate to lose my car over something like this.
Found from searching the net
Test Fans
You can jumper two pins on the DLC that should cause the fans to come on. 1993-1994 cars with the 12 pin DLC can jumper pins A and B. On a 1993, that is the same way that you would retrieve trouble codes from the ecm. The 1994 won't give you any codes, but the fans will engage. 1995-1997 uses pins 5 and 6 on the 16 pin DLC to initiate what is called "field service enable mode". That will cause the fans to come on and operate most sensors for sanity checking. After placing the jumper on the correct pins, turn the key to ON (don't start). If the fans work after jumpering the DLC, your PCM is capable of operating the fans and all fan wiring/relays should be ok.
LT1 Coolant Flow
The LT1 is completely different since it uses reverse flow cooling. The incoming coolant first encounters the thermostat, which now acts both on the inlet and outlet sides of the system. Depending on the engine coolant temperature, cold coolant from the radiator is carefully metered into the engine. This allows a more controlled amount of cold coolant to enter, which immediately mixes with the bypass coolant already flowing. This virtually eliminates the thermal shock present in the old system.
After entering through one side of the 2-way thermostat (at the appropriate temperature), the cold coolant is routed directly to the cylinder heads first, where the combustion chambers, spark plugs and exhaust ports are cooled. Then the heated coolant returns to the engine block and circulates around the cylinder barrels. The hot coolant from the block re-enters the water pump, and hits the other side of the 2-way thermostat, where it is either re-circulated back through the engine or directed to the radiator, depending on temperature.
All of this means that the thermostat housing is the INLET (opposite of most engines), while the water pump is the OUTLET. The water pump (outlet) on the engine runs to the top left (inlet) of the radiator. The lower right (outlet) of the radiator runs to the thermostat housing (inlet) on the engine.
This also means that the "upper" hose on the radiator would be connected to the water pump (mid/lower part of the engine) and is the outlet of the engine, so it should be hot with the thermostat open. The lower hose on the radiator is connected to the thermostat housing (upper part of the engine) and is the inlet to the engine.
Coolant Drain and Refill
1. Park vehicle on level surface.
2. Remove radiator cap.
• Slowly rotate cap counterclockwise 1/4 turn and stop.
• Wait until hissing stops, indicating remaining pressure has been relieved.
• After all hissing ceases, continue rotating cap to remove.
3. Open radiator drain valve Note: catch and dispose of used coolant properly.
4. Open bleeder screws 2 or 3 turns (protect the optispark from coolant).
5. Remove block drain plug on lower LH side of engine and knock sensor from RH side.
6. Allow system to drain completely. Alternate: You can put a garden hose in the radiator neck if you want to force clean water through the radiator. This may not force the water through the block if the thermostat is not open (probably won't be with cold water present). You can remove the thermostat to allow the water to more easily reach the block. Allow to drain after flushing.
7. Close radiator drain valve.
8. Install block drain plug and knock sensor.
9. If you did the alternate flushing and have removed the thermostat, you might want to fill the block with your coolant mix through the top of the water pump before placing the thermostat back in. Some people report that this helps to lessen air pockets. Fill until the water pump remains full, install thermostat and water neck, then continue with the next item.
10. Using a 50/50 mix of coolant to water, fill the system through the radiator neck (bleeder valves open).
11. LT1 coolant capacities for the 4th gen F-body:
• With Manual Transmission - 15.3 quarts (14.5 L)
• With Automatic Transmission - 15.1 quarts (14.3 L)
12. Close bleeder screws when bubbles disappear and only coolant is visible.
13. Fill the coolant recovery reservoir to the COLD fill mark. This will provide the extra coolant required to replace the air left in the system upon the first couple of thermocycles.
14. Install coolant recovery cap.
15. Block wheels and run engine in Park or Neutral with the radiator cap off until thermostat opens (you should see coolant circulating in the radiator tubes).
16. With the engine running, add coolant to the radiator until the level reaches the bottom of the filler neck. This may be tricky if you have an electric pump because coolant may try to gush out-be careful. Install cap sooner if you need to.
17. Install radiator cap.
18. Check for leaks after the engine is up to running temperature.
19. Monitor engine temperature. If the temperature goes up into the red zone, turn off engine and allow to cool. After it has cooled, check the level in the remote reservoir and correct if necessary. Run engine again until the thermostat is open and check again for air at the bleeder screws.
Suggest Flush the Coolant
1994 Camaro Coupe V6 3.4L Overheating
http://www.f-body.com/forum/showthread.php?t=16340
It could be any number of things. First thing I would do is completely flush out the cooling system, refill with just water and do a cooling system pressure check. The tool can be obtained from Autozone on a loan program, if the headgasket is leaking, this test will show it. For what it's worth, the v6s are pretty tough.... headgasket problems are not very common. That being said, starting it up with the radiator cap off should allow you to see if bubbles form in the coolant once the engine is started..... that is a pretty good sign the gasket isn't holding cylinder event pressure aka a blown or partially blown head gasket.
1994 Firebird Formula LT1 5.7L v8 (Fourth Generation F-Body)
Long story of bad mechanics (skip the next paragraph for my question).
After all the shops, this is what actually happened:
Developed a bad water line from the radiator to the thermostat. The spray flooded my optispark (car would not crank). Took to a local Firestone in Columbia, SC to replace the optispark to allow me to find the leak. Firestone found water in the weep hole on the bottom of the water pump and insisted that I had a bad water pump and convinced me to replace it. Firestone did not replace the “coupler, water pump driveshaft” so my new water pump never turned. Got two blocks and returned with bad overheating. Firestone claimed I had a blown head gasket. Replaced the top-half of my engine and same problem. Had a different mech pull the water pump and to my horror found the missing “coupler, water pump driveshaft” (Firestone claims the other mech must have lost it). I have replaced a large amount of the cooling system. Still overheats.
Diagnostics
The list of replaced new parts is – OptiSpark, Sparkplugs, Radiator, upper and lower radiator hoses, water pump, “coupler, water pump driveshaft” ($35 from dealer if you ever need one), thermostat (180 degree), radiator cap, Head gaskets (x2), Valve job, manifold gaskets, exhaust header gaskets (x2). Also jumped the OBD1 connector to force PCM into diagnostic mode and run both fans (they are good) then verified they came on correctly as the engine overheated (confirming the detection circuit).
Currently the engine is still overheating. Pulled the thermostat out and took the lower radiator hose off to see the that coolant flow “surges” out. This meaning that there is good flow with breaks of no flow. Expected to have constant flow like a garden hose.
Question: Still Overheating?
Back to the drawing board, I have been reading trying to find what else could be wrong (see the section below I found on the net). Discovering that the coolant system works nothing like how I thought it did, I am going to drain the system again and hope I have a weird air pocket causing my grief.
Does anyone have any other suggestions? I am out of ideas and hate to lose my car over something like this.
Found from searching the net
Test Fans
You can jumper two pins on the DLC that should cause the fans to come on. 1993-1994 cars with the 12 pin DLC can jumper pins A and B. On a 1993, that is the same way that you would retrieve trouble codes from the ecm. The 1994 won't give you any codes, but the fans will engage. 1995-1997 uses pins 5 and 6 on the 16 pin DLC to initiate what is called "field service enable mode". That will cause the fans to come on and operate most sensors for sanity checking. After placing the jumper on the correct pins, turn the key to ON (don't start). If the fans work after jumpering the DLC, your PCM is capable of operating the fans and all fan wiring/relays should be ok.
LT1 Coolant Flow
The LT1 is completely different since it uses reverse flow cooling. The incoming coolant first encounters the thermostat, which now acts both on the inlet and outlet sides of the system. Depending on the engine coolant temperature, cold coolant from the radiator is carefully metered into the engine. This allows a more controlled amount of cold coolant to enter, which immediately mixes with the bypass coolant already flowing. This virtually eliminates the thermal shock present in the old system.
After entering through one side of the 2-way thermostat (at the appropriate temperature), the cold coolant is routed directly to the cylinder heads first, where the combustion chambers, spark plugs and exhaust ports are cooled. Then the heated coolant returns to the engine block and circulates around the cylinder barrels. The hot coolant from the block re-enters the water pump, and hits the other side of the 2-way thermostat, where it is either re-circulated back through the engine or directed to the radiator, depending on temperature.
All of this means that the thermostat housing is the INLET (opposite of most engines), while the water pump is the OUTLET. The water pump (outlet) on the engine runs to the top left (inlet) of the radiator. The lower right (outlet) of the radiator runs to the thermostat housing (inlet) on the engine.
This also means that the "upper" hose on the radiator would be connected to the water pump (mid/lower part of the engine) and is the outlet of the engine, so it should be hot with the thermostat open. The lower hose on the radiator is connected to the thermostat housing (upper part of the engine) and is the inlet to the engine.
Coolant Drain and Refill
1. Park vehicle on level surface.
2. Remove radiator cap.
• Slowly rotate cap counterclockwise 1/4 turn and stop.
• Wait until hissing stops, indicating remaining pressure has been relieved.
• After all hissing ceases, continue rotating cap to remove.
3. Open radiator drain valve Note: catch and dispose of used coolant properly.
4. Open bleeder screws 2 or 3 turns (protect the optispark from coolant).
5. Remove block drain plug on lower LH side of engine and knock sensor from RH side.
6. Allow system to drain completely. Alternate: You can put a garden hose in the radiator neck if you want to force clean water through the radiator. This may not force the water through the block if the thermostat is not open (probably won't be with cold water present). You can remove the thermostat to allow the water to more easily reach the block. Allow to drain after flushing.
7. Close radiator drain valve.
8. Install block drain plug and knock sensor.
9. If you did the alternate flushing and have removed the thermostat, you might want to fill the block with your coolant mix through the top of the water pump before placing the thermostat back in. Some people report that this helps to lessen air pockets. Fill until the water pump remains full, install thermostat and water neck, then continue with the next item.
10. Using a 50/50 mix of coolant to water, fill the system through the radiator neck (bleeder valves open).
11. LT1 coolant capacities for the 4th gen F-body:
• With Manual Transmission - 15.3 quarts (14.5 L)
• With Automatic Transmission - 15.1 quarts (14.3 L)
12. Close bleeder screws when bubbles disappear and only coolant is visible.
13. Fill the coolant recovery reservoir to the COLD fill mark. This will provide the extra coolant required to replace the air left in the system upon the first couple of thermocycles.
14. Install coolant recovery cap.
15. Block wheels and run engine in Park or Neutral with the radiator cap off until thermostat opens (you should see coolant circulating in the radiator tubes).
16. With the engine running, add coolant to the radiator until the level reaches the bottom of the filler neck. This may be tricky if you have an electric pump because coolant may try to gush out-be careful. Install cap sooner if you need to.
17. Install radiator cap.
18. Check for leaks after the engine is up to running temperature.
19. Monitor engine temperature. If the temperature goes up into the red zone, turn off engine and allow to cool. After it has cooled, check the level in the remote reservoir and correct if necessary. Run engine again until the thermostat is open and check again for air at the bleeder screws.
Suggest Flush the Coolant
1994 Camaro Coupe V6 3.4L Overheating
http://www.f-body.com/forum/showthread.php?t=16340
It could be any number of things. First thing I would do is completely flush out the cooling system, refill with just water and do a cooling system pressure check. The tool can be obtained from Autozone on a loan program, if the headgasket is leaking, this test will show it. For what it's worth, the v6s are pretty tough.... headgasket problems are not very common. That being said, starting it up with the radiator cap off should allow you to see if bubbles form in the coolant once the engine is started..... that is a pretty good sign the gasket isn't holding cylinder event pressure aka a blown or partially blown head gasket.
i really dont know what to suggest, i will leave the suggestions to the people who know a little bit more. all i can say is find a starting point and fix one problem at a time. well i wish you good luck..later
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