Little to no oil pressure at idle. Help Please!

[oldshep]

Hey everybody, when i run my bobbed m109 i have to keep it reved up to have oil pressure. But when i let it drop to idle, oil pressure drops to or near zero. oil pressure regulator maybe? the pump? i really dont want to run the truck till i figure this out. TMs are kinda vague on this. They might as well say " if oil pressure is low, replace engine." thanks guys!

 

[dm22630]

Could just be a bad gauge....

 

[Banshee365]

Listen to the differance in the turbo as well, especially if it's a whistler. When you first start the truck and there's no oil pressure, which is normal on the MF, you'll hear the oil pressure build up in the turbo and it sounds like the turbine is slowing down. If at idle you turbo sounds like it's unloading I'd be concerned but if it sounds good and normal I'd suspect the gauge.

-Kelly

 

[oldshep]

i doubt it. i have a mechanical in it.

 

[oldshep]

good idea kelly. does anyone know much about how the oil pressure regulator works?

 

[oldshep]

but if i still have oil pressure issues what should i do?

 

[OPCOM]

There is somewhere here a diagram of the oiling system, and some details about the pressure regulator, an old thread, I don't see it offhand. The regulator block has two actual regulators inside it. For a fact Bjorn took his apart and it was very gunked up.

 

[cranetruck]

Low oil viscosity (=fuel mixed with it) will lower the pressure.
A bad or sluggish oil pressure sending unit. Take it out and test with compressed air at the right pressure. Not used if you have a mechanical unit, I know.
The regulator on the engine block below the turbo, controls the upper limit (about 70 psi) plus one other function and shouldn't have anything to do with low oil pressure in general.
Another reason could be worn rod bearings....my problem on the deuce.

Edit: Added image (right click and open link in new window for full res)

 

[DeuceNewb]

when was the last time you changed your oil? If its old and worn out that would make a big difference

 

[JDToumanian]

What is the history of this problem, sudden change or gradual worsening?

I suspect the gauge - If the truck has been like this for any length of time I think the engine would have quite a knock...

 

[DeuceNewb]

when i bought my 109 it had low to almost no oil pressure at idle, but upon reving the engine it would build up. I then changed the oil it took care of it, now at idle the pressure is right around 30. the oil in the truck from uncle sam was no good anymore. if it's been a while, put some fresh 15w40 in there.

 

[tm america]

change your oil and filters first then test your gauge even mechanical ones can be off .is it different hot verses cold .if its a big difference when its hot its ussually worn out rod or main bearings

 

[oldshep]

gradual. the oil has been in for a year with about 300 miles on it. truck has only been ran twice a month lately.

 

[M215]

Check the sending unit and the gauge to see if they are rated the pressure. Sending units and gauges are available in 60 and 120psi, if mis-matched they will not read properly. Two of my M35s were mis-matched and read inaccurately low oil pressure. The sending units are marked 60 or 120.
Hope this helps.
Karl