dt-466 no oil pressure

[rch]

One of our Dt-466's has a oil pressure problem.

First it's a mechanical 1995 model, and the engine is rebuilt with a new oil pump.

On start (when cold) the buzzers and gauges indicate no oil pressure. If left to idle and warm up still no oil pressure? However rev it up once and 40 pounds of oil and everything is fine. Also it remains fine all day even with stopping and starting, pressure fine. We have let it idle when cold for as long as we dare but the pressure will not jump up until one or 2 throttle blips. Even our DT tech guy doesn't know what's going on. Is there some sort of by-pass check valve not allowing oil to flow and a blip opens it? i am afraid that on of our genius drivers will start it ant simply walk away without the obligatory blip.

Any ideas?

 

[rancherman84]

i'm going to guess the gauges are electrical?
could it be the things not charging when at idle,then after the throttle blip it starts charging?
i guess i would stick a mechanical gauge in the truck and see what is really going on.
the only valve in the system should be the oil psi regulator valve,i thinks its on the right side of the engine by the oil filters,looks like the head of a big bolt,could be sticking or have a piece of crap in it.

 

[dbarilow]

could just be a bad sending unit. I'd put a mechanical guae in place of the sending unit and see what it reads

 

[holtzer1]

could just be a bad sending unit. I'd put a mechanical guae in place of the sending unit and see what it reads

my thoughts exactly. and..it should have way more than 40psi at cold idle. my pos 6.2 w 234k on the clock is pushing 65 at cold idle and 25 fully warmed up. running a steady 60 down the highway.

 

[Doggy Daddy]

Quite a few years ago I had a SB Chevy that did the same thing. It would even rattle the bearings leaving no doubt that there was no pressure. Turned out to be the pressure relief valve spring on the oil pump was weak, a new high volume pump was the cure.

Now, that motor had (as I recall) about 75K on it when that happened and I had owned it since new so I know that nothing was done inside up to that point. When I first noticed it was shortly after an oil change and I don't remember which oil filter I had used but changing the filter to an AC brand fixed it for a couple oil changes. Then it so that it didn't matter what brand filter I used it still had no pressure until it was revved quickly. What I'm getting at is that possibly even the filter is contributing to the problem. Was the oil pump and relief valve & spring replaced when the motor was done?