I could use a 1974 slant six manifold heat control valve expert!
Hi Guys/Gals: I think the manifold heat control valve on my 1974 slant six Duster is messed up and I could use your advice. Recently, I removed my exhaust manifold and had it ceramic coated. It looked great when it came back, and I noticed that the heat control valve counterweight and spring had also been ceramic coated. Anyhow, I noticed immediately upon first driving the car with the refinished exhaust manifold that the engine sounded very "boomy". It was noticeably louder than before, so I checked the exhaust manifold gasket and also the gasket between the intake and exhaust manifolds. All looked good. I then noticed that when the engine was hot, the end of the counterweight spring was not resting against the peg on the exhaust manifold but was dangling at about the twelve o'clock position (straight up - see photo which was taken when the engine was hot). After 15 minutes of cooling, the spring end was now arched over counterclockwise and resting against the peg. I don't think this is right. My FSM says that when you rev the engine, that the counterweight should turn 1/2" counterclockwise, then go back to its original position. The FSM doesn't state whether the engine should be hot or cold when you perform this test. I've attached a photo of the spring standing straight up at the 12 o'clock position after shutting down the hot engine. The end of the spring looks like its resting against the peg, but it isn't. It's actually about 1/2" away from the peg. Shouldn't the end of this spring somehow be attached to or resting against the peg? I suspect that the guy who sandblasted my manifold might have messed this assembly up. The booming sound coming from the engine concerns me, and I don't want to damage my motor. Does anyone understand how these springs operate and how they should be connected to the stationary peg? Any thoughts would be welcome. Slant Six Dan, please feel free to weigh in if you're reading this. Thanks all!
Hi Guys/Gals: I think the manifold heat control valve on my 1974 slant six Duster is messed up and I could use your advice. Recently, I removed my exhaust manifold and had it ceramic coated. It looked great when it came back, and I noticed that the heat control valve counterweight and spring had also been ceramic coated. Anyhow, I noticed immediately upon first driving the car with the refinished exhaust manifold that the engine sounded very "boomy". It was noticeably louder than before, so I checked the exhaust manifold gasket and also the gasket between the intake and exhaust manifolds. All looked good. I then noticed that when the engine was hot, the end of the counterweight spring was not resting against the peg on the exhaust manifold but was dangling at about the twelve o'clock position (straight up - see photo which was taken when the engine was hot). After 15 minutes of cooling, the spring end was now arched over counterclockwise and resting against the peg. I don't think this is right. My FSM says that when you rev the engine, that the counterweight should turn 1/2" counterclockwise, then go back to its original position. The FSM doesn't state whether the engine should be hot or cold when you perform this test. I've attached a photo of the spring standing straight up at the 12 o'clock position after shutting down the hot engine. The end of the spring looks like its resting against the peg, but it isn't. It's actually about 1/2" away from the peg. Shouldn't the end of this spring somehow be attached to or resting against the peg? I suspect that the guy who sandblasted my manifold might have messed this assembly up. The booming sound coming from the engine concerns me, and I don't want to damage my motor. Does anyone understand how these springs operate and how they should be connected to the stationary peg? Any thoughts would be welcome. Slant Six Dan, please feel free to weigh in if you're reading this. Thanks all!