80 exhaust heat valve
10-09-2011, 05:39 PM
#1
Cruising
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80 exhaust heat valve
My exhaust heat valve actuator is missing the vacuum line. Any ideas? I have had the car for a year and the history is unknown to me. Spent the year painting. Just something I noticed. Thanks.
10-09-2011, 08:45 PM
#2
Race Director
My shop manuals are at work, but if I remember correctly, the vacuum line to the heat riser, comes from the solenoid in the thermostat housing.
10-09-2011, 09:13 PM
#3
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Thanks gbvette. On my car there are 2 solenoids on the t-stat housing. All lines are missing on both. My manual does not show what the routing should be.
10-09-2011, 09:27 PM
#4
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The vacuum line should go from the exhaust heat valve actuator (EFE) to the lower fitting on the Thermostatic Vacuum Switch (TVS) mounted in the right side of the thermostat housing.
Another vacuum line goes from the upper fitting on the TVS, through a check valve, to a vacuum source on the carburetor.
When the engine is cold (as determined by the TVS) the TVS opens to allow vacuum to act upon the EFE.
Vacuum causes the exhaust heat valve actuator to close, which blocks the exhaust flow through the right side, which helps heat the carburetor, which improves the vaporization of fuel, which helps the engine to warm up on cold starts and also helps to prevent global warming / cooling.
When the engine is warm (as determined by the TVS) the TVS closes, depriving the exhaust heat valve actuator of vacuum, which then opens to allow exhaust gases to follow their normal route through the right-side exhaust pipe.
Apply some penetrating oil to the exhaust heat valve actuator linkage. Then, either by using a vacuum pump or pushing upward with your hand, you should be able to actuate the exhaust heat valve to see if it is open or seized shut.
If your exhaust heat valve actuator is in the open position, there should be no problem.
ziller
Another vacuum line goes from the upper fitting on the TVS, through a check valve, to a vacuum source on the carburetor.
When the engine is cold (as determined by the TVS) the TVS opens to allow vacuum to act upon the EFE.
Vacuum causes the exhaust heat valve actuator to close, which blocks the exhaust flow through the right side, which helps heat the carburetor, which improves the vaporization of fuel, which helps the engine to warm up on cold starts and also helps to prevent global warming / cooling.
When the engine is warm (as determined by the TVS) the TVS closes, depriving the exhaust heat valve actuator of vacuum, which then opens to allow exhaust gases to follow their normal route through the right-side exhaust pipe.
Apply some penetrating oil to the exhaust heat valve actuator linkage. Then, either by using a vacuum pump or pushing upward with your hand, you should be able to actuate the exhaust heat valve to see if it is open or seized shut.
If your exhaust heat valve actuator is in the open position, there should be no problem.
ziller
Last edited by ziller; 10-09-2011 at 09:35 PM.
10-09-2011, 09:45 PM
#5
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Great reply ziller. I already lubed it up and it moves freely. I will have to find all the parts to put the system back together. I have to keep reving the engine when it is cold or it will die. When it warms up it runs fine.
