Frozen Intake Valves

Marco Tahtaras

Marco Tahtaras

Well-known member
I local buddy picked up a "Barn Fresh" Model A recently. the intake valves are SERIOUSLY stuck! He managed to get one to move enough to remove with considerable force and several hours work. He had soaked them with Kroil assuming it was a rust problem. What he found was what appears to be carbon buildup in the valve and guides.

I've never heard of anything quite like this. The rest of the engine looks quite good with the head off. Any ideas on something that may get in there and soften the carbon enough to make a difference? He did what seemed to be the easiest valve! I have a couple thoughts but don't yet want to influence the feedback. Thanks...
 
just athought from a couch idea, could you go in with a portable glass or baking soda ,low pressure , and blast a little carbon away?..but then, it would not clean the stuck area?..oh well..this make this site interesting..we get to think..thank you..charles..:o)..
 
There are several old recipes involving nasty chemicals that are generally unobtainable except to chemists but the gun shops sell barrel cleaners to remove powder residues that are baked carbon to a large extent.
 
I kinda like acetone/ATF with heat.. Just keep them warm and wet and try to get them moving.. It works well if they are sticky,but, it might take awhile when their stuck..
 
I would be supprised if spray Carburator Cleaner would not work. Some of the penetrating oils will desolve rust and corrosion but they may not do anything to carbon.

Just a thought.

Chris
 
Flood the valve stems with carbon disulfide. If you can't get them up enough to squirt it under the valve heads, remove the intake manifold to get at the stems. Stuff a rag soaked with it in the port against the stems and let it soak several hours. Diethyl Ether with top cyl lube (Diesel starting fluid in a spray can) works too, but it evaporates a bit too fast, requiring multiple applications, and it will knock you out in a garage.
 
Just to play the devil's advocate here, how could this be? To build up carbon enough to stick the valves to that extent the engine would have to run. If the valves stick the engine won't run hence no carbon. This means before the valves could seize the engine would stop running. I am of the opinion that you have a serious rust problem but carbon will make the job harder.
 
MikeK said:
Flood the valve stems with carbon disulfide.
Click to expand...

I worked on a sausage casing plant project where carbon disulfide was part of the process. It auto ignites at 212F and seemed to be pretty dangerous stuff. Can you buy it by the quart for this sort of usage?
 
James Rogers said:
Just to play the devil's advocate here, how could this be? To build up carbon enough to stick the valves to that extent the engine would have to run. If the valves stick the engine won't run hence no carbon. This means before the valves could seize the engine would stop running. I am of the opinion that you have a serious rust problem but carbon will make the job harder.
Click to expand...

I agree with James, and was wondering the same thing?

I think oil softens carbon, but Kroil or Sea-Foam may work quicker. I would always pick out chunks of carbon with an old screwdriver to get the bulk of it out.

If you look at an oil burning engine with worn rings you will see that the oil getting past the rings has cleaned the carbon off the outside edge of the pistons.
 
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