504 piston question

biggerred

Member
I'm going to have to replace 2 pistons
in the 504 I'm working on. They're
stamped .030. Apparently the block has
been bored. Am I stuck using only .030
pistons, or can I use standard pistons
and make up the difference with rings?
 
finding parts for this thing is starting to turn into a challenge. I can find a complete kit, but ill have to mortgage the farm to pay for it.
 
No sleeves. I thought so at first, but it's a straight block. I'm just going to find a couple of used pistons and go from there.
 
Look to the idea of Knurling the piston skirts, and putting ring groove repair rings in the pistons if needed. If the existing bores are only .003 to .005 worn, straight honing and knurling is a real option, look it up. Jim
 
Well you should be able to get a .060 oversized piston and rings For it and a trip to the machine shop for a bore job and finish hone and your good to go . Then when it wears out again ya bore it and install repair sleeves and start at STD. aqain and ya got two more rebuilds again. Part # i came up with is a 378183R92 and add .060 for size. .
 
One positive thing is there's not the first sign of a ring grove. The 2 pistons need replaced because one had a piece broke off the very top edge, and the other one cracked.
 
All four pistons need to be the same size to preserve balance. The C153 in the 504 is a high speed engine when compared to the old H and M engines. Having different sized pistons could cause some nasty vibrations.
 
Makes sense. Personally, I'd like the owner to part this rag picker out and put his money on another tractor, but it's not my call. I want to do right by him, but get away from this old turd too.
 

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