JD 655 Engine Swap

[jd4310man]

I have an 1987 655. Its in really good condition, Ive been using it to remove snow this winter. So far Ive been able to get it running by keeping it in my insulated and enclosed shop. I also installed a block heater last year to get it warmed up. Today I couldn't get it to run. I Let the block heater warm it up for a few hours until it was toasty warm, still wouldn't start. I did a compression test and all three cylinders are down 100lbs. The glow plugs are getting power and it has a new battery. I need this to start and run when I need it. I would rebuild it but I need something now. I was looking on eBay for running engines and am wondering if I could put the next size engine in it? The stock engine is a Yanmar 3tn66uJ. Would a 3tn72 fit? I remember reading about a guy who did this but cant find the thread.

 

[TimberHole]

I don't know the answer to your question. I was going to suggest an in frame overhaul but a quick search of the parts manual seems to show this isn't a sleeved engine. How many hours are on it? Could also be a head issue. Seems odd to me that all 3 cylinders would be that low on compression. Makes me suspicious something else is going on but I'm just guessing.

 

[Mechanos]

It's entirely possible. Many of the 3tn series share the same block with bore and stroke differences that make up the displacement difference. Such is the case the with the 955's original 3tn82 and the 3tn88 that is in my 955. I haven't done the research on the 66 and 72 to see if they share the same size block.

 

[jd4310man]

I know the engine has a lot of wear, the previous owners didn't change the oil much in the 1300 hrs that's on it. I would like to have a little more power than the original engine, I think that 16hp is a bit low for this size of tractor. I looked on JD parts and was comparing at numbers from the 3tn66 to the 3tna72 that's in the 755. There are differences in the parts that make the engine mate up to the tractor (drive couplings, motor mounts etc...) I read that a 3tne68 is an exact match to the 3tn66? I found a guy in Tennessee that has imported the 3tne68 from Japan with low hours. He wants$1600 for it. Anyway, I just need a good engine that will run when I need it to. This one I have now Is badly wore out.