D4 Still Seized up

Doesn't matter which you push down, so long as you don't push two at once. The engine will rotate either way just fine.

I would push the one I thought was the worst stuck. You might want to 'crack' each one loose individually a few thousandths just to break the rust bond before pushing one a long way. After all, you're really pushing all 4 at once after you move one a few thousandths of bearing clearance etc.

If you wanted to push 2 at once, you can push either 1 & 4 or 2 & 3. From the looks of the head, I would push 2 &3 down enough to clean the cylinder wall above the piston when it gets close to the bottom of the stroke. I would not go all the way full stroke down on 2 &3. Then if it won't rotate with a wrench or bar turning the crank, you can still push 1 & 4 down more easily than if they are at TDC.

Sure is nice and clean now, but I guess the trouble is out of sight.😆

Have you looked in the bottom end to make sure there's not something else locking it up?

I recently was able to free a stuck D2. It was in pretty bad condition. In cleaning things up, I removed the side panels off the diesel and could then see under the pistons. There was a lot of rust there. I took emery cloth and hand sanded the best I could all around the cylinder walls under the pistons. And squirted Kroil up under the pistons. Then poured the diesel into each cylinder and let it burn for a long time. I guess it burned thirty minutes. Then beat on the pistons again with wood and hammer. I finally saw something move ever so slightly. From the time I saw the first movement until the engine finally turned 360 degrees was probably another five hours. Just working things back and forth, sanding under the pistons, etc.

One suggestion......a friend warned me that the mains would probably be dry after the machine sit so long. So, to pre-lube things I removed the oil pressure gauge, clamped a rubber hose to the oil line, then kept fitting various hoses together until I had something that I could screw on a 1 quart oil jug. I then squeezed oil into the tube until I saw oil seeping out of all the main and rod bearings. It took a while and a couple quarts of oil, but I finally saw oil weeping from all the bearings (viewing through the side openings you can see everything). I would try to pre-lube those mains and rod bearings before I got the main engine turning over. Protect the mains if they are still good. Just my .02.

Lock up your sleeves to head screw !

Careful not to run power
Getting stuck in the upper ring

Good luck

Itzik

You need a bigger hammer. Use a block of hard wood that almost fills the cylinder and hit the piston while everything is still hot.
Chuck C

Had the same problem with a 2T two years ago, after many attempts using other mixes the only thing that broke it free was two days of Kroil.

Hi D4 Still Seized up,
Does anyone know how a freed up engine is expected to run? Compression and oil consumption seem to me to be a potential problem. I have a D4 with seized pistons and am considering a complete overhaul. If i did get it turning, the trouble of putting it back together just to try it seems to make it too iffy. What should I do?
D4guy

That would be the best👍 I say do it once and do it right. Plus when you drop the oil pan and undo the conecting rod clamps you can tap on the pistions with wood from the bottom have had good luck with that. As far as how the machine will run if you just freeded up and did not overhaul not sure there would be a pin point anwser for that ever motor/machine is different

All depends on how much money you want to put into the old machine really and how lucky you feel. If you want to just see now it runs, you are gambling a head gasket. And really, if you don't abuse it, the gasket can be reused. I made all the other gaskets I needed from gasket stock. I guess I was lucky, but the D2 I recently got running was stuck really bad and all I did after getting it turning over was hone the cylinders, lap in some valves and slap a new head gasket on. It runs great, good oil pressure and the smoke out the stack seems normal. Of course you can drop some real $$ into one of these engines and it be like new, but for the small amount I play with my machines the return on investment just isn't there.

I think that after you get it freed up and turn it over a few times, check the cylinder wall(s) where the piston(s) were frozen. Depending on how deep the rust ate should tell you if you have to go further.

If it was frozen in just one cylinder, and freed up fairly easily I might go ahead and take a chance, particularly if there's not a real heavy ridge at the top of the liner. Frozen tightly in more than one cylinder, I'd think it would be time for a full tear down and inspection.