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I'm pretty new to all this. I was crawling around under my car and saw this weighted thing with a spring that almost looks like a choke on my passenger side exhaust manifold. It looks like it might rub against the starter if its moving.
What is it? What does it do? Is there something I should do with it?
I'm pretty new to all this. I was crawling around under my car and saw this weighted thing with a spring that almost looks like a choke on my passenger side exhaust manifold. It looks like it might rub against the starter if its moving.
What is it? What does it do? Is there something I should do with it?
Hi F,
The heat riser is there to block some of the exhaust flow when the car is first started from cold.
The coiled spring you see contracts and opens the valve as the engine warms up.
It's presently in the closed position. The square weight would be in the down position when the valve is open.
It appears the one on your car is too rusty to operate. Can you move it with your fingers?
Regards,
Alan
When the engine is cold this valve is closed forcing hot exhaust gas to go up through a passage in the heads and intake manifold and exit out the drivers side manifold . The purpose is to quickly warm the intake manifold under the cab .
When the right side manifold warms up the thermostatic spring on the heat riser valve opens and the exhaust goes straight out . These valves are notorious for rusting in the closed position causing excessive heat under the carb .
Hi 76CS,
I really don't think the heat riser valve has anything to do with emissions control.
I believe it's purpose is to direct exhaust heat into the intake manifold crossover passage to decrease the time it takes for the engine to warm up and the choke to open.
It improves drivability.
Regards,
Alan
Hi 76CS,
I really don't think the heat riser valve has anything to do with emissions control.
I believe it's purpose is to direct exhaust heat into the intake manifold crossover passage to decrease the time it takes for the engine to warm up and the choke to open.
It improves drivability.
Regards,
Alan
That's it and they have been on cars long before emission standards came about.
Mine swings freely, but I don't know if its functioning. Seems like something I could live without though.
Thanks for the replies!
You can buy a spacer designed to replace it. I live in NC where the weather is generally pretty warm so I have no need for it. Been without it here since 1996. No issues.
What is this thing?
