D12 rebuild

yes... thats what i was thinking.. I thought the ORIGINAL pistons were caved inward like a dish... You may have pistons that have already been changed out once... You MIGHT be able to buy one of those aftermarket pistons to match yours.... but , note that that kit is 3-9/16 bore , so the pistons would be 3.560 or so ........... you still need to verify what your BORE or PISTON diameter is.

Edited by steve(ill) - 25 May 2022 at 11:53am

No, i think your motor has been rebuilt sometime in the past... I "think" the 149 inch motors had concave pistons like this.... Maybe someone who knows the details will chime in..

Does it affect performance of the engine

So I don't need to get original pistons I am fine just getting 1 aftermarket one

I currently don't have the money to buy a whole piston kit should I check salvage yards

Best practice is to have them all match.

That said, you might be surprised to know how many car engines have had one cylinder bored out larger than the rest with no one ever being able to tell the difference in the way it ran.

These tractor engines run relatively slow and have relatively low specific power output; for moderate usage you would never be able to tell that there was a mismatch.

I personally know of one local WD 45 that threw a rod out through the block. The old farmer simply removed everything related to that cylinder, put some fiberglass patching over the hole, and ran it with three cylinders.

I wouldn't run mismatched pistons in a competition pulling engine, but anyone who can afford to play that game (I cannot) will be able to also pay for matching parts.

https://www.ebay.com/itm/265667132499?hash=item3ddafebc53:g:~-QAAOSwiC9iasTl

I can't find any pistons online to match the current set and I don't have the money for a brand new engine rebuild kit. Still have to get the size verified by the tractor mechanic near me

So it wouldn’t be the end of the world if 3 matched and 1 was different.

Forgot to mention this is a d12 industrial with a back hoe and loader

Ok I will confirm with the mechanic what's in the tractor currently

That isn't what the other three look like is it ??????? They have to match in looks and bore size !!

I was told it would be fine

Lon has TWO sets of used....one set dished.....one set domed. He doesn't have them mixed in an engine.

In order to be CORRECT, the pistons must weigh the same, have the same design top and be of the SAME exact compression ratio or the engine will shake and vibrate.

I know this is kind of a dumb question but could I hook up a small trailer to my truck and lay the loader of the d12 on it and strap it down and pull it home like that.