Oil pressure problem?

[airbornebandsman]

I have a 1970 M35A2 that I have had for about 5 years I have had the current engine in for about 3. I changed the head gaskets about 2 yrs ago before I moved to GA.

When I first start and drive the truck the oil pressure needle is in the middle of the gauge. It stays there for about the first hour or so of operation and then starts dropping. When I accelerate it will jump up a bit but eventually it just sits at 0. I drove from NC to GA with this problem and had no adverse affects, once I noticed I stopped every few hrs and let the truck sit for 30 mins or so and this solved the problem for another couple of hrs. When the needle gets to 0 there is no noticeable difference in the sound or performance of the truck.

Is this a common thing or could it be something major? I have a trip to Vegas coming up in June and need to know if I may need to replace a major component prior to the trip.

Thanks for the input in advance.

 

[littlebob]

It could be just a high resitence problem caused by a bad gauge panel ground, or it could be bad news. Check all of the connections and see if you can put a jumper from the battery negative to the back of one of the gauge mounting posts? Having the same problem and mines a long term project I havn't finished yet.
I want to eventually put a mechanical on the engine for temp and oil to be able to open the hood and decide good to go or not.

 

[bgekky3]

Put a manual guage on it and check it out. I have guage problems in both of my trucks. The manual guage lets me know what the real oil pressure is.

 

[uscgmatt]

Is your guage a 0-60, or 0-120? If it is a 0-60 make sure you have a 0-60 sender. Mine had the 120 sender w/ the 60 guage, it read 30 cold and about 15 warm. I replaced the sender w/ the correct 120 one and then 90 cold and 60 warm. Hope this helps.

 

[cessnatwin]

I have this going on right now in one of my trucks, if you had a problem you would already know it! Test it with a mechanical gauge, which can be a pain, or just buy a new sender which is usually the problem, and your done!

 

[OPCOM]

low is one thing, "0" is another. Maybe as they say electrical. My temp sender has a bad connection and the reading will move quite a bit. I assume you cleaned up the oil pressure regulator when the new engine was built, or whomever did it took care of that detail. I get about 75-90 cold, 60 at speed, and 30 at idle.

 

[littlebob]

Not my thread, but good info as I have a similar problem.

 

[ODdave]

OPCOM what is this "oil pressure regulator" ??????????

 

[Divemaster920]

ODdave,
It's the thingy behind and below the turbo on the side of engine. You can find more info at the TM 9-2815-210-34-2-2 page 4-196.
And it regulates the oil pressure.

 

[WillWagner]

Ditto on what most have said. If you had ZERO o/p, you'd know it from the lack of engine rotation. As stated above, it is most likely a sender.