The Stovebolt Site Forums The Shop Area Engine Shop Frozen Exhaust Manifold Internal Heat Control Valve

I am trying to free up the rusted/stuck Heat Control Valve inside the exhaust manifold in my 1953 Chevy 3100, 235. The valve/baffle is supposed to open and close based on the engine temperature via a Thermostatic Spring and Balance Weight mechanism. My valve is frozen in one position and I can't budge it loose. I have tried soaking it for days in penetrating oil, heat and tapping it with a hammer, but no luck. Any suggestions?

They can be a PIA. I usually use heat and a hammer
Heat the casting and then tap the rod on the ends back and forth sometimes tapping the weight up and down. heat it, tap it, soak it, It will eventually come loose

If that fails cut it off and drill it out and replace the shaft

soaking it in something like evaporust often does the trick. evaporust and an ultrasonic tank almost always does the trick

You can try an air hammer with a bit which has been ground flat and alternate 'hammering' the end of the shaft and the end of the weight. A fully functional baffle normally has a generous amount of end play, so you won't hurt anything doing this. Once you are able to move the shaft fore and aft, it should create space for penetrating fluid to get in there. You have a combination of rust and carbon buildup which is difficult for penetrating fluid to get in there.
Carl

I have the same problem...mines stuck...open. I elected to leave it alone for now as the engine was running great before the guy took it out that sold it to me. Cold weather running may be a problem however. Guess I'll find out soon enough. Keep us posted git er dun.

I finally got the heat riser loosened up. I followed Thoroc's back and forth tapping advice and 2Carls advice that it was a build up of both rust and carbon. I used plenty of penetrating oil, which helped somewhat. Then I tried a carbon dissolver. I used PB Blasters LMT, (Lawn Mower Treatment), which claims to dissolve carbon build up on pistons & valves. 30 minutes later, a few more back and forth taps on the riser rod and it popped loose. Swings freely now. Thanks.

Thanks for Gitting back to us!
Carl

I have heard that simple green makes carbon just pretty much fall off. I haven't tried it personally, but I have complete faith in the fella that told me. This probably won't help here, but might come in handy somewhere else.