Seized valves on stuck flathead 6

[Cooper40]

Hi again

I posted on here a week ago about my 1949 plymouth with a stuck engine. Go read that post if you want to know the back story of it/me. Pistons/cylinders look good so now we're thinking it's valves. The two pics are of each of the valve "windows" in the side of the block. I sprayed pb blaster all over the valves, valve stems, springs. How would I go about trying to free these valves? I've heard of people prying with a large screwdriver to get them to move up but I wouldn't know where to pry and I wouldn't want to break anything! 

I'll advice is greatly appreciated. Again, read my previous post before this one if you want to know more details. 

[soth122003]

Valves usually do not lock up an engine. As long as the cam shaft lifters push the valves up the engine should rotate. However with valves stuck up, it can stop the engine from starting or running. The cam and lifter push the valve up easier than the spring can bring them down. Hence if the valves are stuck up, they are usually gummed up there.

 

It will be a waiting game. Patience is the key thing here. Soak the valves with your mix of whatever and wait a day or two. Then try tapping on the valves sticking up with a rubber or rawhide mallet. Don't beat them like they owe you money, just light tapping at first, then a little more force. If the valve moves down, let set for a day with a new application of break-free or whatever you are using. If they don't move spray more break-free and wait another few days. I've heard from some members it can take weeks to free up stuck valves and engines. Looking at the pics on your other thread, the valves are most likely gummed up. The solvent should start breaking them free before to long, but if the engine does not rotate, you could bend the valve shaft by prying on them with a screwdriver or pry bar. Then they will be a bite to get out. The key thing is to try and let the camshaft push the valves up using the lifter, as it will apply a more steady even pressure to the valve stem.

 

If you can turn the engine over by hand, try a rotation and see if the valves move. Make a note of witch ones move and just allow them to soak. The ones that don't move, if stuck in the up position, apply break-free and then tap down again. The key thing is to try and let the camshaft/lifter push the valves up. If the engine does not turn, that should be the first thing to try and free up. Pull the radiator and use a socket on the crank and a long heavy breaker bar and try to rock the crank back and forth, starting from left to right as you are looking at it. Again start out light and then steadily apply more force. Chances are it will take a few days to a few weeks to get the engine and valves to free up. Just be patient. If the engine still won't move, pull the oil pan and loosen the crankshaft bearings just a bit. If it moves you know one of the bearings is bad, if not loosen up the piston rods connecting to the crankshaft. If it still does not move, it's more than likely the pistons. 

 

Just remember, take it slow and don't try to brute force the engine. You can also try to use a wood piece (2x4) and a mallet to tap on the pistons. Again don't beat them, just firmly tap them to try and break them free. Once the engine is moving a bit more break-free and try to rotate a full turn watching the valves. 

 

Joe Lee

Edited July 12, 2023 by soth122003

[Sniper]

I bought a 230 to build for my Plymouth and it had stuck valves. I tried all the combinations people have mentioned and the only thing that really worked with a darn was brake fluid. Didn't take me 10 minutes to free up valves that I had spent weeks trying to free up using other fluids.

[JerseyHarold]

Try removing the timing chain and then turning the crankshaft.  That would rule out stuck valves as the reason for being stuck.

[joecoozie]

Sometimes the valves need to be rotated or spun to break up the rust. I know this because......

I had a 1951 Pontiac with several stuck valves and I soaked them, beat them down with a rubber mallet, etc, but they continued to get stuck in the open position.

Since I had the head off, as you do, I used a pair of pliers that had rubber-lined jaws to grab the valve head and rotate the valve (while squirting lube down the stem) This fixed the sticking problem and caused no damage to the valves.

 

Also, while you have the valve covers off, make sure you clean out the area(s) where the oil pools (it's the area below the springs). I'll bet if you stick your finger in there you will find that the pools are loaded with sludge - which is normal for an old engine that was never rebuilt or taken apart. Just clean them out and wipe out the residue. 

Same thing when you drop the oil pan - clean out the sludge and clean the pickup screen, too.

[Young Ed]

8 hours ago, joecoozie said:

Sometimes the valves need to be rotated or spun to break up the rust. I know this because......

I had a 1951 Pontiac with several stuck valves and I soaked them, beat them down with a rubber mallet, etc, but they continued to get stuck in the open position.

Since I had the head off, as you do, I used a pair of pliers that had rubber-lined jaws to grab the valve head and rotate the valve (while squirting lube down the stem) This fixed the sticking problem and caused no damage to the valves.

 

Also, while you have the valve covers off, make sure you clean out the area(s) where the oil pools (it's the area below the springs). I'll bet if you stick your finger in there you will find that the pools are loaded with sludge - which is normal for an old engine that was never rebuilt or taken apart. Just clean them out and wipe out the residue. 

Same thing when you drop the oil pan - clean out the sludge and clean the pickup screen, too.

Wear gloves- good possibility that goop has lead in it from the old leaded fuel

[Cooper40]

@JerseyHarold I would ideally want to do that but I don't have a way to jack it up and it's on grass. 

[greg g]

It's hard to get penetrant past the valve stem, most wants to take the route of least resistance..  be careful wracking stuff, valve stems can break if you are over zealous or off target.  A little heat can help sweating penatrant down the stems.  

[Cooper40]

@soth122003 

Thank you for the reply. Once i have a way to jack the car up, I will and drop the pan and look at the bottom side of the engine. I was also thinking of taking the timing cover off and removing the chain and seeing if it's the camshaft or the crankshaft. 

[soth122003]

If you take the timing chain cover off make sure you mark the sprockets so you can put it back the way it was or you will have to start from scratch and reset the timing alignment of the cam and crankshaft.

 

Joe Lee

[Dan Hiebert]

Don't be lulled by the appearance of the cylinders from above, all of the "stuck" is below the top of the piston.  I'd work on freeing up the engine before venturing into the valve train.  It will be much easier to ID problem valves once the engine is turning.  It's only been a week, some mentioned it took them months to free their engine.  Someone also suggested getting the oil pan off - if after your patience runs out trying to free the engine from above this should be a next step, as you should get a better picture of what the cylinders look like from below.  You may discover that it will be futile to try to free the engine, saving yourself some aggravation, or you could discover a slightly different approach to try next.  The PO did not do you any favors removing the spark plugs - that opened the engine up to the atmosphere, our climate up here can create a lot of condensation, (the past month I've been indoors working on stuff dripping moisture from it).  These L6s are not rare, MoPar used the same basic engine for 30 years, with industrial applications even beyond that.  Replacements are out there and they're still reasonably priced.  Although I've grenaded a few, I have never dealt with a seized engine, but I believe I would relish the challenge of getting one freed up - up to a point.  I can't add any better advice on how to free up a seized engine than already given, other than don't be unwilling to cede defeat to the point it turns you off to old cars.