stuck valve
 

bought this 8rt engine, got it running on seven cyl, has one stuck valve, Anyone got a way to free it without pulling head. had it soaking overnight in pb blaster. tried allen wrench, feels pretty solid. all suggestions appreciated, mike

Re: stuck valve
 

Marvel oil or Rislone has lots of adherents, pick one. Seem to have a very good track record for this purpose.

Re: stuck valve
 

If Marvel Mystery Oil doesn't do it then your next step is disassembly.

Re: stuck valve
 

I had at least 7 stuck valves on the 52 Merc when I started on it a few years back. Time and patience works. I sprayed penetrating oil down the stems through the spark plug holes. After a while some gentle tapping with a hammer and punch worked for me. Of course the valve has to be open and the cam shaft in the right postition so you are not tapping against the cam and lifter. I used this same method on the 39.

Re: stuck valve
 

try a mixture of 50% acetone and 50% auto transmission fluid, continue to soak and as stated above a short wood dowel and light taps with a hammer on the valve head. I think what really occurs to stick the valve is rust on the valve stem and guide. cast iron is porous and oil will eventually drain out of it, letting rust occur

Re: stuck valve
 

I helped a friend with a '31 Model A with a stuck valve and used RalphG's method successfully. I used PB Blaster under the head of the valve that stayed open. We left that a few days with repeated sprays on a daily basis. Then I got a 3/8th wood dowel and a 16 oz hammer (no need for the BFH) and tapped the valve down. Friend cranked the engine over with the hand crank and the valve came up again on the cam, friend cranked beyond that and I hit the top of the valve again and found it went down a little easier. We did that about a dozen times and stopped when all it took was a minor tap on the valve with just the dowel to get it to seat. Plugs back in, rolled the A out of the garage, shut the door, started it up and amid the smoke from the solvent, the motor quickly started running on all 4. Happy but tired friend.

Re: stuck valve
 

Tks for the info, will keep trying, valve is stuck open but is mostly hidden by head. will post results after a few days of soaking.

Re: stuck valve
 

I guess I don't have the patience some folks have. I just pull the heads and work them for a while. I decarbonize & clean everything up then put them back on with new gaskets. There is always a risk of breaking studs or bolts but it's still faster than soaking & waiting. I like to see what's going on in there on an engine that's new to me. Some times you find a broken ring or things of that nature. The Marvel Mystery Oil is the cat's meow for stuck valve stems whether you pull the heads or not. You can run it in the fuel or oil in specific quantities. Pour some down the carb while it's running. It'll smoke for a bit but sometimes it will free up stuck rings or valve stems.

Re: stuck valve
 

I don't recall how long it took but did not seem too long a time for the valves on the 39 to unstick. I recorded some of it on video just for fun.
https://youtu.be/xn8q0ygd3k4

Re: stuck valve
 

Sure, try a few things to get it unstuck, but if it doesn't free up after reasonable effort, you should really pull the heads and intake to see if there is a more serious problem (broken spring, etc.). Don't risk an otherwise good engine with "heroic" efforts.

Re: stuck valve
 

I agree with the advice above. Have patience. You want to be sure the oil pump isn’t stuck also....... Mark

Re: stuck valve
 

Sometimes they stick due to varnish. A little carb cleaner takes care of that.

Re: stuck valve
 

The best penetrating fluid is the 50/50 mix, it really works.

Re: stuck valve
 

Ended up pulling head and pulling engine through-tapping valve down numerous times. no luck. soaked in acetone and trans mixture for two days, valve still wouldn't go back down. Finally pulled intake and found the keepers missing at bottom of valve. Valve still very sticky-pulled valve assy and ordered new parts. Looked all over for Keepers even used magnet. No luck-now wondering were they went. Mike

Re: stuck valve
 

Maybe dropped into the oil pan below

Re: stuck valve
 

One more time, at the point where you're at now I would be doing a "permanent" fix with some bronze-lined guides and stainless valves, you will NEVER have a "hung" valve again in your entire life with this method!

Been down this road hundreds of times doing the Flatheads, it IS a permanent cure!

If your guides aren't damaged you can simply line them and save the cost of buying new guides at least! We've been doing a couple hundred a year lately, many for the forum members up here!!

Thanks, Gary in N.Y.

P.S. Wishing all here a safe and "Happy Holiday" season!! "Merry Christmas and Happy New Year"!

Re: stuck valve
 

Merry Christmas to Gary and his loved ones! May your New Year be filled with health and happiness.

Thank you for your contribution of sound, helpful advice on this forum. My engine might not have come together without your help.

Re: stuck valve
 

Hi Gene, "Thank You" this means a lot to me AND my family and I'm glad to be able to contribute!

We do so many different type builds (Chev's, Pontiacs, Buicks, Olds's, etc.) and I enjoy the Flatheads more than most others. Every one is kind of unique to each customer.

Thanks, Gary in N.Y.

P.S. Wishing all here a safe and "Happy Holiday" season!! "Merry Christmas and Happy New Year"!