I took my 442 on a ride yesterday up the interstate. I was running about 72 MPH with my 3.08 gears and 27" tires. I suppose the tach would have been around 3000 rpm. The oil pressure gauge was reading 55 psi and after 20 miles it dropped down to 48 psi.
Here's the issue.... I pushed in the clutch and coasted for a 1/4 mile or so and after I hit the gas again the pressure bounced back up to 55 psi and stayed there. I did it again on the way home and it happened again.
Is it possible my oil pump was starting to suck a little air because of the oil being up in the engine?
The oil was less than 1/2 quart low.

 

Ok I have a stupid question. Is there an sending unit on the motor that I can just hook a gauge up to get oil pressure or do you have to put an external sending unit on.
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Live sex

 

I don't think you would be sucking air with all the oil in the top of the engine at 3,000 RPM. If that was the case, there would be few Olds engines left today. I will let one of the engine experts give their toughts on this one. I would guess an oil pump if I had to guess but it would only be a guess.

 

You can remove the factory sending unit and install fittings for an aftermarket gauge.

 

If you are asking is 48 psi low I don't think so. I don't see an issue and agree that the pump wasn't sucking air.

 

I don't think 48 psi is low It just seems odd that my oil pressure would change 15% in a few seconds. I topped off the oil and I'll see if the extra oil makes a difference.

 

When one is referring to engine RPM, actual numbers (from a tachometer) as opposed to random supposes, is always useful. In this case, however, accurate numbers are probably the key to explaining your "issues".

Normally, this is due to a change in viscosity caused by a rise in oil temperature.

This is where that tachometer comes into play.

At what RPM did those pressure differences occur?

If you believe what you read on the Internet, it would be the cause.

If you live in the real world, it is not possible.

Norm

 

Norm,
3000 RPM is not a random guess. That is why I included the gear ratio and tire size. It is probably a closer estimate than my 40 year old factory tach. Maybe you like to force me to practice typing by clarifying things that need no clarification. When you push in the clutch and coast for a 1/4 mile the engine is at idle even though the car is still moving very fast. I can't tell you how fast during this time because I'm slowing down, it would be changing every second.
Now the next point I didn't make perfectly clear but figured people would realize when I hit the gas, I returned my speed back up to 70 miles per hour which would mean the tach would be back to where it was before I pushed in the clutch. The logical question from you should have been...Did you return back to the same speed? and I could have answered with a very short "yes" Instead of all this BS.

The reason I am curious is that I ran a pan dry on a 454 Chev when my GPS was reading 124 miles per hour and I noticed my oil pressure gauge very close to zero. Don't ask me what the tach was reading. The engine was just over a quart low on oil. There seemed to be similar needle movements of my oil pressure gauge on both cars. I let off the gas and slowed down and the oil pressure went up. Which would add some credibility to the oil being up in the heads etc and the need for oil restrictors. I'm not sure I buy all the hype about the need for restrictors but it made me want to ask the question.

 

Did you and our President take the same "question answering" class?

1. Forget everything and start from the beginning.
2. Drive the car at 72 miles per hour
3. When you see the expected decline in oil pressure, raise your speed to 74 miles per hour.
4. Note the change (if any).
5. Lower your speed to 70 MPH.
6. Note the change (if any).

Norm

 

Start from the beginning? LOL, Norm, you do have a sense of humor. It seems you don't buy into the oil restrictor hype. I don't either. thats all I really wanted to know. Me and Mr Obama don't have much in common. I thought Bill Clinton could dodge a question better than anyone. Imagine the BS Hilary had to listen to. Bill's a guy we could learn a few tricks from.

 

I think it is from thermal expansion and the viscosity going down.As the engine heats, things like bearings expand faster than the crank causing a drop in pressure. It could be the thermostat sticking temporarily and a short spike in engine temps. I have an old Ford plow truck and if you drive it with the plow blocking the radiator the engine gets hot and the oil pressure drops accordingly. I put a 140 degree thermostat in it and problem solved.Check the thermostat.

 

It's possible, I do have a temp guage and it doesn't spike or change. I do have a new aluminum radiator that keeps it well below 200. But why would the oil pressure raise 8 pounds in 10-15 seconds when I coast and after resuming 70 mph again it stays there for another 10 miles and slowly go back down again? couild oil cool that quickly?
I think it's either an oil temperature related issue like you mentioned or lack of oil.

 

New radiator----could be some air in the system causing an intermittant air block. You would see the temp rise some however.

 

On my last build I took the oil restrictors out..just continue to keep an eye on it, like someone said 48# is fine. My oil pressure is around 72# cold, and 48-50 during cruise.

 

My opinion is there is trash blocking the return paths from the top of the engine! Pull the valve covers and make sure the oil returns aren't blocked. Also, with higher viscosity oil it may take longer for it to return back to the pan. Olds BBlocks do have an inherant oil return problem and sometimes if you install a hi volume pump it only makes it worse. I agree 48#'s is not bad.

 

how does changing a t'stat increase air flow thru the radiator?

 

Good point,
It is a fresh 455 motor.
I am running 20-50 Valvoline high zinc oil. When I change the oil I'll drop to a 10-30 Brad Penn and see if it changes anything.

 

Yes, I often use it to make a point.

Seems you would rather continue your "typing practice" than to recognize that point.

It seems that you have not read any of my numerous posts on the subject. For example: https://classicoldsmobile.com/forums/171389-post16.html

In order to to "buy into" it one would have to accept the false premise that it is based on.

Norm

 

I run 20-50W oil...and a K&N Filter

 

Posted by MN71W30
........ you do have a sense of humor ........

Yes, I often use it to make a point.

Yes you do, but it's not very good.

Quote:
Originally Posted by MN71W30
........ Did you and our President take the same "question answering" class? ........

Seems you would rather continue your "typing practice" than to recognize that point.
You lost me on that one Norm.

Quote:
Originally Posted by MN71W30
........ It seems you don't buy into the oil restrictor hype ........

It seems that you have not read any of my numerous posts on the subject. For example: https://classicoldsmobile.com/forums/171389-post16.html

I try not to read your posts, I'm on high blood pressure pills

In order to to "buy into" it one would have to accept the false premise that it is based on.
I do think you may be right about that.
Dave
__________________
Quote:
Originally Posted by 380 Racer
Quote:
Originally Posted by 88 coupe
None of us can know what we haven't learned yet .....

........ I saw Norm's "helpful" answer and encouragement as a slam ........

 

http://www.breitbart.tv/obama-gives-...ng-over-taxed/

Norm