stuck piston

Im disassembling a Type 4 2.0L, it is down to the shortblock, I have removed heads and 3 cylinders. Although one piston is rusted fast to one of the cylinders which I cant remove. I have tried soaking the whole crown of the cylinder in WD40 overnight, gave it a tap with the hammer to no avail. Piston is stuck to high up to release the gudgeon pin.

I do not intend to keep the pistons or cylinders. Any help or suggestions before I break out the angle grinder and cutoff wheel? 🙂

bashing does wonders! just don't look at my collection of mangled engine parts, okay?
Rings are brittle. They give way eventually.

Worst case, i guess you could cut the barrel along the top and split it open. At least you wouldn't damage the conrod.

Hi,
Did this on my CZ125 years ago which had exactly the same problem.

Drill big hole through piston crown, away from the gudgeon pin/conrod.

Get hammer, cold chisel and hacksaw blade.

use the blade to cut toward the barrell walls, use cold chisel and hammer to crack the piston crown in either the cuts, or take chunks out. The rings will shatter eventually and they are a pain to try and cut. Once at the outside you can start sawing along the depth of the piston. Go carefully if you want to save your barrell. Once the full depth cut is nearly done your hammer/chisel/belting should crack the piston from crown to skirt bottom.

Eventually.........

It took me 6 nights to get the damn things unglued...........


Enjoy
Ctefeh

If you dont want the cylinder, go the cut off wheel - you will get a tremendous amount of satisfaction from making it tow the line 🥲

Yeah i am not particularly enthusiastic about bashing it too hard, because I dont want to damage any of the journals. Looks like the cutoff wheel is the go 🙂 I think i will try to cut off the bottom of the cylinder and try to extract the gudgeon pin.

Try heating it up then splashing cold water on the piston, the aluminium should shrink quicker than the steel bore. Heat works wonders...

76camper wrote:Try heating it up then splashing cold water on the piston, the aluminium should shrink quicker than the steel bore. Heat works wonders...

Like above but try WD40 but be careful as it may catch alight if too hot. It tends to suck the WD40 into the join between mating parts helping to free them up.I use this for exhuast studs etc.
Also is it possible to undo the rod bolts and remove the piston/cylinder/conrod from crankcase to make it easier to work on. Not sure about this, just an idea.
Cheers
SAS

nope cant get to the rod bolts. Might try the propane torch, but it is probably easier just to use the cutoff wheel. Thanks for the replies guys

GEt the FBH and a decent block of hard wood that will fit inside the barrel. then get your mate to pull on the cylinder while you wachk away with the wood and the F ing big hammer

Yeah i managed to get it off last night. Cut off wheel with a hammer and chisel 😀 managed to start cracks down the cylinder and hack it off 🙂

That would've been fun and satisfying to get the #$%^! thing apart in a shower of sparks!