Recently overhauled the gas engine on my Farmall 656. This included replacing the sleeves.
When I brought the block in to my machinist to have the old sleeves pulled (I hadn't ordered the new ones yet), he said that it would be good for him to measure the piston bores first, after the old sleeves had been pulled.
He said he had noticed a lot of problems with engine sleeve sets today, either being too large, or conversely too loose in the block bores.
He blamed much of the problem on how tractor sleeve sets are now being manufactured in China or India, and they aren't always the most accurate on outside tolerances.
Ideally, the dry sleeve should be able to be pushed about 1/2 to 2/3 of the way into the block, using moderate hand pressure. If it is too tight, you run the risk of cracking the brittle cast iron of the sleeve.
But worse is if the sleeve is too loose in the bore. He says that in this situation, the sleeve is only being supported by the top counterbore ring, and not around the entire outside sleeve diameter by the block. This causes the sleeve to "flex" with the up-and-down piston movement, eventually cracking the sleeve near the top.
What happens then, is that the piston pulls the broken part of the sleeve downwards. Where it hits the crankshaft. And then you've got a real mess. He has had that happen to several farmer's tractor engines.
Apparently, when the block was coming down the assembly line, the sleeves were a "select fit". I noticed on the deck head of my 656 engine block, there are some stamped letters: A B C D. The blank bore was first measured, and then the assembly tech would stamp by each cylinder, the proper over or undersize sleeve that was to be installed in that particular bore. They had in addition to the standard size sleeves, .0015 and .001 or .002 overbores, and and also some underbores.
So---if you are replacing the dry sleeves in your block, it's best to measure the bores after the old sleeves have been pulled. And then compare that measurement to the new sleeves you are going to install. In my case, I had to get one sleeve with a .0015 overbore O.D.
There are some companies that sell special size sleeves. With all the "tractor engine overhaul kits" being sold out there on Ebay and the Internet, it's good to remember that some of them come from overseas, and could be of uncertain quality.
Just a head's up.
When I brought the block in to my machinist to have the old sleeves pulled (I hadn't ordered the new ones yet), he said that it would be good for him to measure the piston bores first, after the old sleeves had been pulled.
He said he had noticed a lot of problems with engine sleeve sets today, either being too large, or conversely too loose in the block bores.
He blamed much of the problem on how tractor sleeve sets are now being manufactured in China or India, and they aren't always the most accurate on outside tolerances.
Ideally, the dry sleeve should be able to be pushed about 1/2 to 2/3 of the way into the block, using moderate hand pressure. If it is too tight, you run the risk of cracking the brittle cast iron of the sleeve.
But worse is if the sleeve is too loose in the bore. He says that in this situation, the sleeve is only being supported by the top counterbore ring, and not around the entire outside sleeve diameter by the block. This causes the sleeve to "flex" with the up-and-down piston movement, eventually cracking the sleeve near the top.
What happens then, is that the piston pulls the broken part of the sleeve downwards. Where it hits the crankshaft. And then you've got a real mess. He has had that happen to several farmer's tractor engines.
Apparently, when the block was coming down the assembly line, the sleeves were a "select fit". I noticed on the deck head of my 656 engine block, there are some stamped letters: A B C D. The blank bore was first measured, and then the assembly tech would stamp by each cylinder, the proper over or undersize sleeve that was to be installed in that particular bore. They had in addition to the standard size sleeves, .0015 and .001 or .002 overbores, and and also some underbores.
So---if you are replacing the dry sleeves in your block, it's best to measure the bores after the old sleeves have been pulled. And then compare that measurement to the new sleeves you are going to install. In my case, I had to get one sleeve with a .0015 overbore O.D.
There are some companies that sell special size sleeves. With all the "tractor engine overhaul kits" being sold out there on Ebay and the Internet, it's good to remember that some of them come from overseas, and could be of uncertain quality.
Just a head's up.
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