B7200 Oil Pressure

[sdcassel]

I have been chasing down the cause of low oil pressure on my 1986 B7200 HST 4WD.

I've changed the sending unit, pulled the timing cover to inspect the front cam plug (it was intact), replaced the oil pump and oil pressure relief valve, but still have only about 12 psi (at idle) and 24 psi (at 2500 rpm) when cold, but it drops to about 4 psi (at idle) and 10 psi (at 2500 rpm) when warm.

I don't have the know-how to get to the rear cam plug, and the local Kubota service guy says there is only one on the front anyway (although the parts manual shows one on each end). He says an engine overhaul is the only option. The engine runs and sounds fine to me, but he says it's noisy when throttling back down, indicating mechanical wear. Should I insist he check the rear cam plug, since if that's missing an overhaul might not be necessary?

[ipz2222]

Welcome to the (low oil pressure club). See "low oil pressure L235".
I can't answer your question for sure but, every eng I know of the rear cam plug is in the back of the case where the bell houseing goes. A leak there will put a lot of oil on the ground, not low oil pressure. Unless it is blown completly out, then a lot of oil on the ground and lower oil pressure.

[sdcassel]

So are worn bearings the only other reason for low oil pressure?
What if I do nothing and run with the marginal oil pressure? What more damage can it do?

[Service Dept Vic]

Kubota lists the following Probable Causes of Low Oil Pressure in your B7200 as follows:

1) Excessivley low oil level. repair all oil leaks and refill to "full"
mark on dipstick.
2) Incorrect weight, diluted or inferior oil being used. Drain and refill
with recommended grade and viscosity of crankcase oil.
3) Defective or improper oil pressure guage. Replace.
4) Plugged oil intake screen in sump. Clean.
5) Releif valve sticking open or broken releif valve spring. Clean or
replace.
6) Air leaks in suction side of oil pump or badly worn pump.
7) Excessive bearing clearances within the engine. Replace worn
bearings.
8) On pre-1981 Tractor division engines on both B and L Series and 6
cylinder M Series Tractor Engines, check the oil passage plug on the
end of the engine camshaft. (see Service Bulletin 79-07)
9) Check condition of engine oil. contaminated with fuel or coolant.
10) Engine idle speed too low-check specification (800-900 RPM)

[sdcassel]

Thanks; I had completed all of those except the bearing clearances. My Kubota mechanic says it will cost big bucks to tear down and check all clearances; he doesn't think it is worth it!

[sdcassel]

The mechanic also thinks he's hearing piston slap, so the cylinders may have to be bored and oversized pistons installed.

[Service Dept Vic]

Wow. He's real good if he can hear piston slap in a Kubota diesel.

[sdcassel]

What is your opinion of need to rebuild the engine due to the marginal oil pressure?