Case 930 Oil Pressure

[fairchm]

I have about 10 hours on my 930 c/k after a complete engine rebuild. All has been fine until I recently noticed that my oil pressure has started fluctuating. Runs about 40psi, then drops to 20 and appears to randomly swing back and forth.


I do have some additional potentially useful information.

It has recently dropped below freezing for the first time since I owned the tractor. The oil appears to be clean and free of water. I"ve changed the oil and filter once since the rebuild (15W-40).

A new oil pump was not available during the rebuild, so I selected a lightly used unit. Cleaned it , checked clearances.

Never seen like before. Any one have ideas?
 

[jon f mn]

Did you check your gage?
 

[casecollectorsc]

Are the bearings the same clearance as the crankshaft is ground to? In otherwards a crank ground .020 under needs bearings to correspond. I overhauled a 403 IH combine engine one time and ordered the bearings and put engine together and back on combine and when engine was warm 10# pressure. Take it off and back apart. They had given me std. bearings on a .020 shaft. I learned to check after that.
 

[DKase]

I have a 54 DC that does that when it is 1 qt low on oil. There must be a leak in the suction line to the oil pump. Possibility if the gauge checks out OK.
 

[fairchm]

Thanks everyone for the tips. I purchased an extra gauge and need to hook it up. I'd dismissed the gauge as a possibility as I didn't think a bad gauge could cause such odd behavior.

In regards to bearing clearances, I didn't make it clear but the pressure was rock solid at 40 psi for the first 10 hours then suddenly started acting up.

Oil pump sucking air is an interesting idea. I don't remember any O-rings or other sealing devices on the oil pump inlet. Need to look at the manual again.

Thanks again
 

[fairchm]

Verified today that the problem is not the oil gauge.