: Oil pressure problems



Fiero STS
02-09-04, 09:40 AM
I have a 97 vin y motor. Oil pressure cold is 80 + psi. when engine warms up oil pressure is 10 psi or less. Oil pump has beem changed, no apperent problems with bearings oil samples are tested and show no wear metals. engine has 17k miles on it. it appears that oil is getting way to warm and thinning out. using thicker oil only helps for awhile but it still thins and pressure drops I used an infared heat gun oil pan 250 degrees oil filter higher but it is close to exhaust manifold so I am not sure if reading there is accurate. Any Ideas as to the cause of oil heating?

maydog
02-09-04, 01:02 PM
I believe 10 psi is the normal hot operating oil pressure for the northstar. I will try to look it up again.

Fiero STS
02-09-04, 03:47 PM
The manual says minimum of 7 psi but what is normal? do all engines run this low? I'm use to seeing oil pressure in the 30-50 psi on most othe engines. and everybody I know with a caddy has no gauge.

maydog
02-09-04, 05:52 PM
The aurora has a digital guage, i do not know how accurate it is. When it is hot it lies below 10psi. Its been like that for 2 years.

Aurora By Olds
02-11-04, 11:54 AM
10 psi at hot idle is acceptable. You should see it jump to between 20 - 50 once you start driving, depending on engine speed. I've heard of some of the older N*'s dropping down around 4 psi at hot idle, and it never seemed to bother anything.
As long as you get good pressure at higher rpms, you shouldnt have to worry....

Fiero STS
02-11-04, 01:56 PM
I have great oil pressure over 1000 rpms, even hot 50-60 psi. Just low rpms, hot, in gear. Gets way low. Doesn't make any noise, just looks bad on the gauge. I guess I won't worry too much as it seems to be a common occurance.

Aurora By Olds
02-13-04, 12:53 PM
That type of behavior sounds perfectly normal for the N*.
You should be ok.

Anthony Cipriano
02-13-04, 02:54 PM
I have a 97 vin y motor. Oil pressure cold is 80 + psi. when engine warms up oil pressure is 10 psi or less. Oil pump has beem changed, no apperent problems with bearings oil samples are tested and show no wear metals. engine has 17k miles on it. it appears that oil is getting way to warm and thinning out. using thicker oil only helps for awhile but it still thins and pressure drops I used an infared heat gun oil pan 250 degrees oil filter higher but it is close to exhaust manifold so I am not sure if reading there is accurate. Any Ideas as to the cause of oil heating?

Perfectly normal. The engine does not need much or any oil pressure at idle. The Northstar engine has a very large capacity oil pump that is crank mounted to maximize capacity (it turns at crank speed instead of half crank speed like other oil pumps that are driven off the distributor drive) so it will supply plenty of oil at higher engine speeds. Just doesn't make much oil pressure at idle. This is good for friction losses and fuel economy as making "too much" oil pressure when it is not required just makes the engine more inefficient.

Anthony Cipriano
02-13-04, 02:58 PM
I have a 97 vin y motor. Oil pressure cold is 80 + psi. when engine warms up oil pressure is 10 psi or less. Oil pump has beem changed, no apperent problems with bearings oil samples are tested and show no wear metals. engine has 17k miles on it. it appears that oil is getting way to warm and thinning out. using thicker oil only helps for awhile but it still thins and pressure drops I used an infared heat gun oil pan 250 degrees oil filter higher but it is close to exhaust manifold so I am not sure if reading there is accurate. Any Ideas as to the cause of oil heating?


By the way. What oil viscosity are you using and are you running the oil cooler? The Northstar has an oil filter adapter with ports for an oil cooler in most applications. In the tight confines of a Fiero the pan is getting very little air flow so the external cooler would be recommended if you don't already have it. 250 is not too hot for engine oil at all. It is probably on the warm side for normal driving but under high speed driving it would be perfectly normal. I wouldn't worry unless the oil gets over 290 or so. Consider 300-305 about the absolute maximum for engine oil.

If you want to know oil temperature you really need to measure it in the pan. Find a VOM with a thermocouple reading provision and snake a thermocouple wire down the dipstick tube to read the oil in the pan for an accurate reading.