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Unfreezing an Engine

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I'm posting this here for the expert advice I always get from you fellow Jeep fools. Perhaps the advice will by applicable to other MJ'ers.


Topic is unfreezing a stuck "Go-Devil" L head 134 engine from a 1951 CJ3A.


I've got the head off, engine out, strangely I don't have a 1" 3/8" socket to try and turn the front pulley bolt so maybe with the proper leverage it will turn but that's out for now. From the bottom end (with the oil pan off) the engine looks pristine, except for the fact that some previous mechanic swapped around the rod caps, there's an odd cap and the remaining 1,3,4 caps are not on the 1,3,4 pistons. But never mind all that.


I can't get any of the caps off - I'm pulling with vice grips on the sides careful not to scratch them. These rod bolts are different from normal studs, they have girdles that stop them from being pulled through the rod when tightened. I've banged them with a plastic mallet. No joy, none of the caps are coming off.


I'd like to disconnect the rods before the mains but its just not working.


I've soaked the engine completely full with used motor oil for 4 days, I've soaked the cylinders with gas for a day, I've blown a whole can of PB blaster on everything that turns. Nothing budges yet.


The engine sat with its plugs out for many years, who know how many. But luckily, only Cyl #4 looked rusted on the walls and I think that's the culprit. When I soaked it with oil, the other three cylinders allowed the oil I poured in the cylinders to leak through the rings.


All the rod caps look good, they should come off, unless there's a rust weld I can't see inside the journals. I know I could pop it off if I disconnected the mains, then applied liberal amounts of cheater bar leverage, but I'm trying to avoid that!


Any of you old timers know any tricks?




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Oh boy, is this bringing back memories. Always used straight ATF but the Acetone should help.

Take a piece of aluminum or brass and place it on the end of the rod bolts. Tap the bolts out until they clear the rod caps. You need the soft metal, or piece of Oak or Black Walnut to get the bolts started, broke loose. When the ends of the bolts are even with the caps use a pin punch to drive them on out. If they are really tight, you might want to screw the nuts back on the rod bolts to beat on. They don't have to come out of the rod. Just clear the cap. A Oak 4X4 will fit in the cylinder. After removing the cap rotate the crank until there is clearance between the rod and crank journal. Place the Oak, or hard Walnut 4X4 in the bore. See how hard you can smack it with a sledge hammer. Good luck. Jim

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Ok when all the liquid potions fail, remove the crank as best you can. Remember this is to salvage what is possible. Get out the sledge hammer and a piece of wood to hammer the piston. When that failed I got my electric drill and relieved the piston of the mutch of the centre and hammerd the weakend remains out. Desparate measures for sure.

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I have heard folks using brake fluid for a lube to pop a froze engine loose.....I have never done it.

I cannot imagine brake fluid in an engine doing anything other than creating endless misery.


I've popped frozen engines loose by using a length of hardwood dowel placed against the cylinder wall (so it bears on the edge of the piston, not the hollow center) and striking sharply with a moderately heavy hammer (NOT plastic). Move from one cylinder to the next in rotation. Helps to have been soaking in rust penetrant for some time before the attempt, but it sounds like you have that covered.


Just be careful that you don't punch out the center of the piston top.

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The vinegar did it. I was amazed. I started to take the flywheel off and while removing it, she turned! I cranked it a little to loosen the caps slightly. Pulled those off easily, three pistons came out easy, and I just tapped the stuck piston from the inside with a piece of wood and it pushed right out. The vinegar trick was pure magic.

I think the engine looks pretty darn good. My micrometer measured between 3.14"-3.16 in all the bores and there's no noticeable ridge at all.


Now I just have to get the darn lower pulley off!









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