M812 Cummins oil pressure

[armytruckdiesel]

I'm a new owner of a 1977 M812 Bridge Truck with the NHC250 Cummins engine. What should the normal oil pressure be at operating temp for idle and at driving speeds?

What is the best place to buy rims to convert this truck over to 1600x20 single tires?

Thanks,
Andy

 

[DaveP]

my XM818 runs about 35-39 at idle and 62-64 at full rpm full load. these are at 190*

 

[armytruckdiesel]

Mine seems to be 30psi at idle and not much higher at full load. What is the most likely cause or remedy? Any thoughts?

 

[DaveP]

gauge ? how long since the oil was changed ? not sure. maybe wiil wagner will pop in here and give you some ideas.

 

[WillWagner]

Check it with a known good manual gauge, Daves correct, 35-40 at hot idle and 60-65 high idle. Usually not too many o/p issues with these engines. Depending what type of lube system you have, FFC or non FFC, you can check the regulator without removing the pump. Check the gauge 1st, it isn't normal for the o/p to not go up with increased engine speed. If the gauge is good, i'll see if i can post some scans from a manual to walk you through the regulator thing.

 

[armytruckdiesel]

I will check the gage. Thanks for the advice / Andy

 

[derby]

My new rig( M812)runs 60 psi @idle and around 90psi @ high idle @ 190 deg.the gauge sets at about 5# when truck is off. a little off subject (and hate to ask out of my own stupidity)but where does the fuel go from the primer line that connects to the engine pre heater?

 

[DaveP]

do you mean after it enters the nozzel ?