Looking for JD engine parts

[Moukie]

Hello,
I have been posting on the JD owner's forum, and am hoping to gain all the insight this group has to offer as well, as I know some of you may not read in the other forums. I made a questionable purchase a month ago; an early '90s JD 755 CUT with the Yanmar 3TNA72 (UJ) diesel engine. Questionable only because as soon as I got it home the oil light began to flicker. Investigation with a test kit shows 11-14 psi at WOT, and well below 10 psi at idle. Likely dangerously low for a machine that was advertised with a "strong" engine. Oh well, buyer beware! And, I love to tinker and fix things, so may the work commence!

I have already done a good bit of fixing and maintenance (including 15/40 Rotella, filters, leaks, glow plugs/relay, tach cable and hour meter, and a bunch more low-cost items, but decided to at least make some decisions on the engine. I sort of suspect the engine needs rod and main bearings, only because these could be likely contributors to low OP. Engine sounds smooth, with no knocking.....yet.

I contacted Hoye tractor, as they seem to supply a lot of new and used parts for these models. They did not seem interested in supplying engine parts. I see on ebay where I can get a complete engine rebuild kit from China for a 3TNA72 Yanmar for about $500 USD. Seems reasonable, but I know there is always risk in purchasing aftermarket; maybe more so when kit is from China.

My question is really about options. I have to assume that Yanmar built thousands of these diesels for a range of applications, and for every one that went to Deere, they stamped UJ after the serial #. Does that sound reasonable? I ask because I went to the local JD dealer Friday and they want over $300 for rod bearings for ONE rod. If I go with JD parts, I will have $2,000 in rod and main bearings. I really do not see that as an option. Before I did that, I think I would order a Chinese kit and use the parts I need and throw away the rest; if someone can confirm the guts of a Yanmar 3TNA72 and a 3TNA72UJ are the same. Are there other options, such as having a machine shop make a set? Wonder if that is an option, and what the cost might be.

Then there is the option of running until failure. Assuming rods and mains are the culprit, what is the likely failure? Thrown rod, spun bearing, all of the above?

Thank you in advance. I really am in a conundrum, and am potentially facing having the nicest 755 around, with the worst engine condition. He He. Ah, the situations I create for myself.

David in rainy SC

 

[gimmodog]

if you run until failure you will spend much more than the $2000 you are trying to save. If you spin a bearing you will probably have to have the crankshaft ground down then oversize bearings. Put in the heavier oil as was suggested in your other post then do the pressure test again. That may give you good enough pressure that you can run it without worrying about spinning a bearing. Gotta at least try it, that is your least expensive option. If the pressure is still not up to specs then you can start looking at the other options. As stated above you can measure the bearings and see if anyone can match them up or see if the Yanmar without the UJ suffix is the same.

 

[joecdeere]

i didn't know if this would help your search -

 

[jaydee325]

I ask because I went to the local JD dealer Friday and they want over $300 for rod bearings for ONE rod.

I would find another John Deere dealer. I've never seen rod bearings cost that much for a small diesel. Green Parts Store dot com has them listed on line for $20.61 each for Deere parts. John Deere ROD BRG 445+ AR97517

How many hours on this engine? I'd do more investigation before I'd just decide it needs a rebuild.

 

[Industrial Toys]

John Deere sadly knows nothing more than part numbers. Just what is on their screen. More and more, I find, if you want real nitty gritty information, the OEM is the LAST place to bother going. That information is somewhere in that organization but not available to you, the consumer.

I would find a Yanmar rebuilder in the US (possibly marine) and pick their brains.

 

[pmsmechanic]

Just following.

 

[kenmac]

don't know where you are located. You might want to check out these people Fredricks Outdoor.
I have no idea if he has any JD parts for that size tractor, but they will tell you if they don't

 

[joecdeere]

you need to find a better dealer!!!

this is off the Deere site linked to my local dealer here in Atlanta these are three each of standard and oversized rod bearings!!

 

[Moukie]

Hmmm, funny. I now look at my JD dealer website and see similar prices as shown above. That is great, and thank you so much for the direction. That gives me hope. Just for kicks, does anyone have any experience with the China-made engine rebuild kits? I suspect my entire engine is very tired, as it is not easy to crank when under 60F. Working glow plugs will certainly help. Other than that, seems to run out great; just very low oil pressure.
Also - would it be possible to change all rod and main bearings and rear main seal without pulling engine? I guess no way on seal, uh?

Thanks so much for the knowledge.

David in cold, rainy SC

 

[Moukie]

I got my new glow plugs in last night, and tractor started right up. Makes me happy to be fixing all the little things. Tachometer also worked; no telling how long that has been broken, as hour meter reads 1,024. May really be 10,000? Who knows. I did not run long enough to see if hour meter is again working, but will this weekend.

Next comes the final major leak; the power steering cylinder. I have to cut and re-weld that one. That will be a challenge, but i cannot let it go as it leaks even without tractor running.

Still contemplating what to do with the engine.

Thanks for all your guidance.
David in SC