Oil pressure Question

[84tt]

Hey guy's just had some questions

I have been holding off for a while before asking on the board.
A while ago I was cruising down H2 when my oil pressure dropped off.
I was doing about 4000rpm at 80 mph or so.
I usually have pretty good oil pressure.
On start up I usually get 70-80psi.
Cruising I usually get into the 50's to 60's
Idle when it is hot usually 15psi to 20psi.

Now I get 40psi max on start up....then it slowly drops off as it starts to warm....but since I am scared of the low oil pressure I shut it down.

So far I have pulled the pan checked the rod bearings(good)
I didn't check the mains though
I re-installed a new pickup.
I pulled the front cover and checked the clearences on the pump and such.
Still the same result.
Just wondering if guy's have any info...
Also what kinda pressures do you guys get.
Thanks

 

[Hawaiian Turbo]

Any metalics in the oil/oil filter? 4000 rpm @80mph?!?! Dang!!!! I still need to get there and look at the seats and console if you still have them.

 

[84tt]

No real chunks of metal in the filter or the screen. there was maybe a normal amount of junk from breaking in the engine.
Still got the seats.
Yeah 4000rpm/80mph= I only got three gears!


What are your normal pressures?

 

[Hawaiian Turbo]

I hope you changed the oil and filter AFTER the break-in. There shouldn't be any chunks, but a metalic film or swirl like substance. I forgot you had a T-400 also. I personally don't like reving the 6 that high for long periods of time, it doesn't seem to like being high reved like the SBC's. Just my personal opion.

Starting press was 80, then warmed up idling was 20, and the press corresponded with the RPM's, (going up with them).

Since no scoring on the rods, I'd check the mains next.

 

[HI85WH1]

Just a thought...

Derrick (tazgn) had oil pressure problems... wasnt it the gasket for the cover or something like that?

 

[Hawaiian Turbo]

Yes, he put a different gasket on.(the pump one )

Koa however was, I think driving and all of a sudden it dropped.

 

[HI85WH1]

Dunno, it was a suggestion...

I thought Derricks car had oil pressure then lost? Never mind... he had no pressure from the get-go...

Something about the bypass hole or something like that...

 

[Hawaiian Turbo]

Yes, I think it was the bypass hole

That's good, the more minds thinking, the better!!

 

[tazgn]

This doesn't really sound like the same problem I had. My problem was the oil pressure would come up to normal for about 5-10 sec. and then go away to nothing. It was due to the HV front cover isn't 'exactly' the same as stock in one area of the gasket mating surface near the bypass hole. So the pump with prime from the oil in the cooler lines, and then after it started, it would suck air from this small area. I can send pics of the gaskets that show exactly what I'm talking about.

Derrick

 

[HI85WH1]

Hey, what about the pressure relief in the pump?

 

[84tt]

The pressure relief seems good the spring is strong. I even swapped it out for another I did everything i could possible think it could be.
I am going to try and pull the cam out and make sure the front cam bearing did not spin causing the holes not to be aligned.
The only other thing it could be is a spun main bearing or the front cover has a problem.
But as far as I could tell the front cover and pump are good....the clearances are all tight.
I even tried blowing out the pressure side passages to see if it was blocked but I could not really be sure if it was partially blocked or not. thanks for your time.

 

[HI85WH1]

Koa, do you have an oil pump primer? maybe you can see what kind of oil pressure you have static (via the drill), without the motor running?

Just a thought, Rob