Cannot Budge seized 251

[55 Fargo]

Hi all, I have this seized 251 engine ina parts car, it was rebuilt back in 1956, bearings all standard, rings/pistons .030 over.

I have the head off, been pouring oil down the cyls, and over valves for quite a bit of time.

Today I borrowed a neighbours 3/4 inch socket set, put on the socket, attahced the johnson bar, and I could not get this engien to move, not one bit.

My question to you guyus is, should I use as suggested before on other threads, diesel, or penetrating oil, what would be best?

I have no idea if it is stuck valves, or rings, and hopefully not a seized main bearing.

The trans is coupled with a fluid drive, and M^, don't think they could hold back this engine in any way.

I want to free thsi engine, it is my hopefully rebuild candidate, as it has full flow oil filtration, and is a 251 , even the right engine numbers for my car...........Thanx Fred

[BobT-47P15]

Don't know how effective it really is, but some have said to pour Coca Cola down

the cyls.....that stuff will eventually eat anything.

I tried diesel fuel and also Marvel Mystery Oil on the 54 Plym stuck engine. After

it soaked quite a while, tried cranking it over using the starter PLUS a bar and large

socket while cranking. No luck.

I think some have also used a piece of 2 x 4 and whacked it with a hammer to try and tap

the pistons down.

[JerseyHarold]

Flathead sixes can be difficult to free up. If you go slowly you lessen the chance of breaking anything. Some things to try:

Disconnect the timing chain so you're only working on one shaft at a time (cam/crank).

For pistons: I've used thin plastic (transparent milky kind, like a bathroom cup) cut to a point to dig crud out from between the top of the piston and the cylinder. Then shoot PB Blaster around the edges of each piston. Cut a block of wood to a cylindrical shape just a little smaller in diameter than the cylinder. Put it on top of each piston and vibrate with a small air impact chisel (without a blade in it). The repetitive shaking should help free things up. Work in short blasts and vary which cylinder you're in.

Valves: Take off side covers. Spray PB Blaster around valves, stems, and lifters. Remove as many valves as you can, soak and vibrate the rest, and when they're all out see if the cam turns.

Hope this helps.

[Normspeed]

Fred, I'm guessing the pistons/rings are stuck in the cylinders, that it's not the cam or crank or valves holding things up. I think Harold and Bob's advice is on the right track. Hope you get her unstuck.

[55 Fargo]

Thanx for the ideas Guy's, I will try and see what may work.

I am not thinking I will get this baby unstuck and then run her as is.

I wan to free her up for rebuild.

I going to hopefully pull this engine out this fall, easier to store and work on.

I hopefully will rebuild her in the not too far future, even if I have to break the pisont sout, I just do not want to damage the block,cam,crank or bearings.

I am thinking this would be the best engine for rebuilding.

My current engine is a 1951 Plym 218 25 inch block engine, it runs pretty decent but leaks oil out the pan and rear main pretty darn good, but starts very well, has good oil pressure and decent uniform compression.

My Uncle put this 218 into my Chrysler in about 1985, he claims this engine was from a wrecked car, originally owned by a farmer, and it had low miles, he just cannot rememeber how many, but no where near a 100000 he says, about 50 to 60 k on this engine, otherwise he would not have installed it into the car to begin with........Fred

[JerseyHarold]

Why not just do the rear main seal and the pan gaskets and call it a day?

[55 Fargo]

Why not just do the rear main seal and the pan gaskets and call it a day?

Yes that will get done, rear main seal jobs are a real PITA to do in-car, may just do the pan, if your referring to my 218 engine.

My 251 engine is for eventual rebuilding and high-perfing so to speak, so I will either do this engine or my current in-car engine, I can use a 251 crank,rods and pistons if I want to make a 251 out of the 218, or go with bigger pistons , and make a 228, will still shave head and deck block, go with split exhaust, and a 2bbl Webber carb.

But for now I have a good running engine in my car, so I am not forced to deal with the stuck 251, but as an engine it would be a good candidate for rebuild simply because it is a 251 and has the factory full-flow filtration.

I also own a running 228 flathead, it is coupled to a 4 spd trans, ina 1955 Fargo truck frame, it has a 70s Cordoba rear end. I hope to find a cab for this and make a truck too.....Fred

Edited August 12, 2009 by Rockwood

[dezeldoc]

Fred, if you are going to rebuild it pull it out and pull the crank and push the pistons and rods out 1 by 1. you are wasting your time trying to free it up just to rebuild it. if it is stuck that bad most likely it won't free up. coke does not work tried that and just made a mess. soak it with marvel oil and go from there.

[garbagestate 44]

When my 251 was seized, I tried a witches brew of chemicals that were supposed to work but didn't. I did notice that the oil sat in some of the bores but passed through others. The oil that just sat on top of some of the pistons as it turned out were the ones that were stuck. I wound up using a large crows foot on the end of a long extension the end of which I pounded with a lump hammer to drive the pistons out of the bore. I set the crows foot on the wrist pin part of the casting figuring that would do the least potential damage to the piston. At that point I still had the crazy idea that the pistons were going to be re-usable. The last 2 that I did were the ones at the top of the stroke. Eventually using a block of wood and a hammer, I got them down enough to ream the ridges and force them out the same way.

[55 Fargo]

Yah, brute force, I have no problem replacing the pistons, as along as the block,crank,cam are okay.

There is no rige on the top of these cylinders, the valve shamber is super clean to with no sludge.......Fred

[Young Ed]

Fred we just freed up a SD220 binder motor. Bought liquid wrench in a gallon(not the spray kind) and let that soak a few days on each one. Freed it right up. If that doesnt do it you are onto the 4x4 shaved down to the size of the bore. Even if you do get it to turn I'd say you are looking at at least a ring job before this thing runs great.

[55 Fargo]

Fred we just freed up a SD220 binder motor. Bought liquid wrench in a gallon(not the spray kind) and let that soak a few days on each one. Freed it right up. If that doesnt do it you are onto the 4x4 shaved down to the size of the bore. Even if you do get it to turn I'd say you are looking at at least a ring job before this thing runs great.

Hi Ed, this I can try, can get my woodworking Dad to make round blocks of hardwood in his shop.

I will get some liquid wrench, and douse the cyls, and see what I can do.

When and if I can free the pisotns, will rebuild this baby anyway, so want to make nmy racing flattie out of it..........Fred

[Young Ed]

If you are rebuilding it anyway then you can knock the pistons around more. Dad plans to rering and reuse the pistons on the IHC motor. They all came out successfully too. You can also unbolt all teh rods and mains pull the crank and knock them out from underneath one at a time.

[wayfarer]

I suggest using alot of caution when you get heavy handed with a 6lb hammer. It is very possible to break a cylinder wall by banging on the piston. Drill through the top of the piston with a ½" bit...make about a thousand holes and take the piston out in chunks.....unless you want to sleeve the hole....

.

[dezeldoc]

I have beat the heck outa pistons and never broke a cylinder, it would take some pretty thin casting to break through.

[55 Fargo]

The nice thing about this engine is this, no cylinder ridge, valve chamber clean, when it was rebuilt in 1956, it had all bearings standard, and .030 pistons/rings, I really believe it may not have that many miles on her, and hopefully will be a good rebuild specimen someday.......Fred

[RobertKB]

Best advice given so far is to pull the head and pan, and to then remove the crank. This avoids damage to both the crank and rods when pounding on pistons. Also, pistons can be pounded up or down to help loosen them. I think if you pull the crank first you will not have much trouble removing the pistons.

Edited August 15, 2009 by RobertKB

[55 Fargo]

Best advice given so far is to pull the head and pan, and to then remove the crank. This avoids damage to both the crank and rods when pounding on pistons. Also, pistons can be pounded up or down to help loosen them. I think if you pull the crank first you will not have much trouble removing the pistons.

Thanx Robert, I also read your PM, very good advice.....Fred

[James_Douglas]

Get a big drum. Put the engine in. Go to the local oil stop and barrow some used oil for a week. Fill it up and let it soak.

Take it out and try it.

James

[55 Fargo]

Get a big drum. Put the engine in. Go to the local oil stop and barrow some used oil for a week. Fill it up and let it soak.

Take it out and try it.

James

Hi James, an experienced mechanic I know from PA also suggested the same thing, that also sounds like it could work.....Thanx Fred

[Tony WestOZ]

Hi James, an experienced mechanic I know from PA also suggested the same thing, that also sounds like it could work.....Thanx Fred

This method can work but usually all you end up with is a large mess. Oil everywhere and still a stuck engine.

Best method I have found is to strip the engine down and remove the crank and what pistons that can be removed. Usually its one maybe two pistons that are stuck. Lot easyer to work on with none of the other stuff in the way.

[jimwheeldon]

My 50 Biz coupe had sat in the weeds since 1968-motor was locked tight. I pulled the head kept soaking her down with a combo of cheap oil and kerosene mixed 50/50. I tried everthing to break her loose with no luck. Finally I hit on the idea of putting her in gear and just rocking it a little back and forth...high gear worked best. she freed up!!! I got it running by priming it with aerosal fogging oil. It smoked and stunk like crazy the first 20 min. or so. That was 2 years ago, she continues to run very smooth-doesn't smoke or use oil . It even starts consistently in below zero temps! I hope you have as good of fortune as I did-I still am amazed I didn't have to rebuild or do valves or anything. Good luck.

[James_Douglas]

Tony,

If it is frozen it will usually work. If it is rusted, then all you end up with is a mess as you said.

If you can heat the oil, it helps.

James

[1just4don]

This may be slightly OT but pertains to this subject well. This guy was into restoring rusty dusty tractors,of which many are stuck tight. He parked the tractor against his favorite tree(maybe shaped correctly for this) with the front end about 3-4 feet of the ground,in gear so full weight of front end was directed to stuck engine. Opened spark plug orifices and filled with GOOD penetrate such as Kroil and filled and soaked all else down also. The story I was told was there was NEVER a subject tractor that didnt give up the stuck feeling. How this relates to cars,I am sure the weight of the car off the ground would assist also. keep filling spark plugs and leave them out till the car or tractor drops down and meets the earth. IF the engine is out ,all bets are off and dont know how you would get equal torq to it. Other than the wood tap and crank removal as talked about. My imagination says this requires a pretty good clutch to work effectively also,but am told it DOES work!!

not all penetrates are created equal either,,,Kroil or PB Blaster would be my first choices. WD-40 and some others similiar,my LAST choice. AND if your doing stuck engines it ONLY makes sense to buy by the gallon rather than the spray can!!

[PatS....]

I took the head off my 49's original engine (frozen) and found a broken valve, and after the pan was off, I found a bunch of cotton on the oil pick-up...a mouse nest.

Wouldn't have run long even if it was loosened.

I did put some oil into the tops of the cylinders, but the oil only stayed on 3, the rest it drained out past the rings and onto the floor.

I got a small hunk of 4X4 and hit the 3 locked pistons once or twice every time I went by. After a week, it moved.

It's in rough shape but still OK for a rebuild.

Fred, if you have done everything, take the head and the pan off. It'll tell you a story I bet.

Edited August 16, 2009 by PatS....