M725 blowing off oil filters!

[maddawg308]

Okay, for those of you who don't know the story, my M725 hasn't really driven in a LONG LONG time, sitting in a field. I have been slowly rebuilding it. Well, now it sits at the brake shop, ready for some work to be done on that end. But, the shop owner wants to idle the truck into the shop, and to do that, it must run.

No problem, it's done that before. Sorta.

He ran it a couple times, and each time the oil pressue is so high that it blows the oil filters off the block. Over 150 psi or so, he tells me. He says that there usually is a pressure relief valve or something to prevent that, but he's not sure about the design of the engine, so he can't be sure.

Help?

[hiker]

The oil pressure relief valve is located inside the oil pump. Reference Tm 9-2320-244-34 page 75. Figure 3-42. The end plate of the oil pump will need to be removed to access this.

Robert-CA

[BCOWANWHEELS]

also take the oil filler cap off and put your hand over it and see if theres compression in the crankcase. you,ll know it if there is. you could have a bad head gasket or even a crack.

[jfnemt1ff1]

Mike If you need some pics I can email you some I have a used pump that I can take pics of. There is a spring and a check ball type thing that needs to move up and down.
John

[maddawg308]

An update - just got a call from my mechanic since the brakes are done. He fixed the problem, said after he opened up the oil pump on the side of the block, it was all clogged with old garbage oil and sludge, and the pressure relief valve was toasted. He pulled the unit, rebuilt it, and runs like new. Starts around 90 psi, and when it warms up, drops down to 60 psi or so. GREAT!

[brute4c]

Thank you for the update....something else to add to the knowledge pool!
Glad it wasnt worse....might want to pull the oil pan, can be done without pulling anything else, and check to see what all might be laying in there...

[maddawg308]

Roger that, brute. Any idea who would have new oil pan gaskets while I'm at that?

[randyscycle]

If there was a lot of sludge in the pump, you may wanna pay him to pull the pan and clean the sump screen too. Just some cheap insurance.....

[brute4c]

Civvy and mil pan gaskets would be the same...try the usual suspects for that...might have to make one if you cant find one...

[rpgdeity]

I got a pan gasket from Memphis not too long ago, in fact I think they have all the gaskets, as I got almost every gasket minus the head gasket from them while I was at it.