new/used/rebuilt engine needed for JD 4100

[Mike_Lipke]

You are gonna find that that little diesel is cast iron.
Cast iron is cheap, stable if overheated. No reason for a tractor to have aluminum block, since weigh is not an issue.

 

[VA_Joe]

Which begs the question - if the block is cast iron then why would they bother using sleeves in a small tractor engine since - unlike a big rig or large industrial equipment - the engine can be easily removed for reboring. It seems like the cost/value equation is a little out of whack. Then again - it might explain why Deere wants so much for a new engine.

BTW - for guys that have done this on farm equipment - is there a healthy aftermarket for engine parts (pistons, rings, and etc.) like there is for cars or are the parts produced in such low quantities that they are only available from the OEM.

Joe

 

[MetalChicken]

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BTW - for guys that have done this on farm equipment - is there a healthy aftermarket for engine parts (pistons, rings, and etc.) like there is for cars or are the parts produced in such low quantities that they are only available from the OEM.

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There sure is here in the UK.
You can get parts more the vast majority of tractors. With 'classic' tractors (60's - early 80's) actually going up in value year on year a pretty big market exists to support them.

 

[tlbuser]

No easy answer. Not all of the small tractor engines are the same. Some are sleeved, some like the deere 4100 aren't. Ease of remaval is relative also. Splitting a tractor to get to the block is (to me) not necessarily easier than pulling a car engine.

 

[VA_Joe]

You're right - easy is a relative term. I guess the newer tractors with fuel injection electronic sensors, and etc. are probably getting to be as complicated as a modern car engine (digital cameras are a good thing). The only advantage is that you will probably never have to lift the tractor to drop the engine like you need to do on the newer cars and minivans.

 

[coloradotrout]

Thanks for all the input.

Re: TW, I have both the HF 1/2" and 3/8". There have been a few times when I wished I'd had the 1/4" - little stuff obviously. I was more concerned with HF accuracy.

Re: engine detail -- it's a 3cy, no sleaves, cast iron. A Yanmar 3TNE74.

Earlier posters were suggesting an in-frame rebuild consisting of new rings, ? pistions, ? bearings, and a de-glaze.

And yep, I had know about draining both coolant and oil.

But nope, have not started yet. It was sub zero here the past few days.. and I need to add some lighting to the shop. What I really need to get done is the dirt work before I tear into it.

Is the in-frame a bad idea? Just a ring/piston/bearing job? I like the idea of taking the parts to a machine shop and getting their opinion. Anyone happen to be in the north Denver, CO to Fort Collins area?

 

[coloradotrout]

I got some feedback from a machine shop today, that rebuilding may have some gotchas. They mentioned they had a small Yanmar engine recently that required boring and they also polished the crank. It was about a $3600 job in total. The noted I can bring the whole engine in or parts in, etc. and they will work with me. Unfortunately they are about 45 miles away, but at least I know I can take my "box of parts" somewhere if I need to. He mentioned "mic-ing" the cylinders? What is that? And also checking for tapered cylinders - that there may be more wear at the top than bottom. How do I do that? How do I know the head/valves are OK or not OK?

 

[Mike_Lipke]

Usually, not always, but ursually, an engine that has low hours will not have the problem of cylinders that are so worn that they are in need of machining. You will likely still see the cross hatching from the factory, which indicates very little wear.
If your engine overheated just once, the rings can lose their temper and burn oil, have low compression, etc. But, cast iron blocks are pretty tough, and it is unlikely, not certain, but very unlikely that the block is warped.
The head you can bring in, and have them check it for warpage. They can also check the valves. They are also likely, but not for certain, but likely not burned. They can tell you when they do the pressure test. I would have them put in new valve seals though. They are cheap, and they have the spring compressor so it isn't that much to have them put the seals in.
You will have to set valve clearances once you get the head back on and torqued.
As Nat King Cole used to say, "Chances are.....", you just need rings, but of course, anything is possible. Tons of questions will be answered when you get the head off and take a gander into the cylinders. If you see scoring of the walls, everything changes. But smooth cross hatched walls will mean good news.

 

[VA_Joe]

You never know what you have until you tear it apart (and at that point you are committed). The oil problem might not even be the rings. As said earlier - the various diagnostic indicators (compression, leakdown, oil/coolant mixing, and etc) will at least give you an idea as to the nature of the problem.

If you only use the tractor for a few hours a week and do not see any noticeable loss in power - then keeping it as is might not be a bad option. Even a hundred dollars a year in burned oil is a lot cheaper than even a simple rebuild (its not like you need to pass emissions). It's just that if you do it - do it right and make sure that the engine is brought back to spec so that you will never need to go back in.

BTW - The $3600 price tag on the yanmar sounds like the machinist did a lot more than just polishing and reboring (like disassembly/reassembly and then some - that's a lot of labor for a pro).

Joe

 

[cp1969]

"mic-ing" means using a micrometer to check the size of something. In the case of bores an inside micrometer will do the job but a bore gage is much better. These are not pieces of equipment you'll want to buy for a one-time rebuild ($$$).

You can do a shade-tree check for bore diameter and taper but first you'll have to have a new set of rings and have the pistons out of the bores. (I guess you could use an old ring, but I never have) What you do is slide a new ring into the cylinder near the top, square it up the the bore as best you can (the piston, upside down, works good for this) and use a feeler gage to check the end gap. Do the same thing at the middle and bottom of the bore and compare the end gap measurements. If within spec, you're done. If they are anywhere close (this gap will open or close ~3x faster than the actual bore taper) to each other then the bore is not tapered, either.

I would lay money that all you need is rings. But while you've got the head off and pistons out, you might as well do the valves and bearings.