YM165 Low oil pressure

[5030]

Low oil pressure may be a failing oil pump but they don't usually fail. It could be a weak spring on the oil pressure relief valve. With that number of hours I would not think the bearings could be that worn already.

That would entirely depend on if it was maintained properly and the oil and filters changed in a timely manner. If not, those hours could be indicative of worn bearings or other internal issues.

 

[5030]

Why I NEVER buy a used tractor unless I know exactly how it was maintained. Always a crapshoot if you don't know.

 

[5030]

You might try switching to a straight grade lube oil like say a straight 40 weight instead or even a 50 weight like they use in Harley Davidson's.

 

[careyo63]

I've always ran 20/50. I'm in the south so the summer temps. are very hot. Up N. were it's cooler and cold BT. not really a need for it. All Org. 100 Hr. Oil and filter cahnge for 16Yrs.. Oil use! 1/2 Qrt. 100 tach, Hrs. maybe Walmart brand oil and Fram. Had a problem finding them Yrs ago so Napa filter now. Fram 3593 A NAPA 3262

 

[mutt606]

I've had the tractor for 15 years, my father-in-law had it for 20 before that. It has always been babied, oil changes yearly and kept garaged. Not sure why I have bearing wear.

 

[careyo63]

Pull and check pump then. I already of done it!

 

[etpm]

Since you dropped the pan you could now Plastigage the bearings. If they are within spec. then you would know the problem lies elsewhere.
Eric

 

[careyo63]

The bearings had wear you would see it in the pan! Esp. since you changed the oil you would have seen it in the Dirty oil and in the drain pan. I get all kinds of nasty stuff in the drain pan no metal though. It was real bad the first few oil changes. Whale oil was my guess!! true.

 

[mutt606]

Finally got around to tearing down to inspect.
The big end bearings had 0.003 - 0.0035 of clearance when checked with plastigage. So they fall within spec. There is some light scoring that I can catch with my finger nail.

I pull the engine and finished teardown. The main bearings appear worn. The gold color is not a camera issue, it appears the crank has worn through the silver colored layer of the bearing material.

The bores appear to me (I'm no mechanic) to be ok with some light wear.

Crank looks perfect to me (again, I'm no mechanic).

I'd like some input on how to proceed.

My initial thoughts are:
Gasket set
Hone and new rings
Oil seals
Main and rod bearings
Oil pump
Lap the valves
Do the valve springs need replaced? no idea

Clutch still looks decent, I don't plan on spending money there.
Any other thoughts?

 

[winston1]

I like your train of thought. Personally, I would not replace the valve springs.