H Oil Pressure Problem

[Doug Kieta]

The oil pressure on my 51H fluctuates between 15 and 25 psi with what appears to be a random pattern. The engine runs well, and very cool. Most times, it gets higher the longer I run the engine. What steps should I take to try and correct this problem. BTW...it does not burn oil.

 

[Janicholson]

A loose oil pump intake could be one cause. Fluctuation is the interesting element. Getting higher pressure as it warms is odd, implications include the expansion of something that closes up a leaking component. If you pull the pan to check the pickup, plastigauging the rod bearings, mains (as possible) and inspecting the cam bearings can be done. An H is normally full scale on the gauge till very warm, then no less than 45psi, and at Idle above 30. (using 15-40 oil Jim

 

[Tom Fleming]

In addition to what Jim has posted, have you checked to make sure the gage is working properly?

 

[Tom Fleming]

gauge I should say.......

 

[Claven2]

Not sure about an H pump, but many of the letter series pumps are known to have erratic oil pressure readings as the pump cover plates wear. It basically results in oil bypassing the pump gears at times and lowering pump performance.

IF you had that problem, the fix would be to replace or re-surface the inside of the cover plate to get a tight fit, and a new gasket and cutoff valve spring.