adequate oil pressure

[ace58]

Should the oil pressure be raised, with a different spring or shim kit in oil pump, to compensate for modifications to stock oil system ie -10 (5/8") hose and assorted fittings, remote 2 quart oil filter, etc? It currently has between 22 and 25PSI hot at 650-700RPM idle and increases to 40-55PSI at higher RPM, according to 1999 factory gauges.

[Peter J. Bierman]

Sounds normal to me, I have about the same pressures.

Peter

[toyboxrv]

There is a common misconception that changing a spring can change oil pressure. Oil pumps put out volume, not pressure and the spring only limits maximum pressure.

[ace58]

Thanks for the reply. GM sold a kit for the small block oil pumps years ago that consisted of a heavy duty, high pressure spring (white, I believe). I am not familiar with the diesel oil pumps and was curious if a similar type of modification could be performed.

[JohnC]

Oil pressure is controlled by a pressure relief valve. The springs you refer to adjust the relief pressure. This limits the maximum pressure of the system, but does not affect pressure at idle, when the volume capacity of the pump is the limiting factor. It also does not correct oil pressure that falls off when the oil gets hot.

That said, 45 psi at 2000 RPM is plenty of pressure for these engines. Any more is a needless load on the engine and can contribute to oil consumption in the turbo.

[KallyI]

Just as a matter of interest, the oil pressure on my 1997 6.5L, at an idle, is 40 psi, and at highway speed (50 mph up), is 70 psi. I have owned the truck since it had 19000 kms (about 11800 mi.), and it has always been like that. I now have 214000 kms (133000 mi.). Is this abnormal or normal for these engines? Should it be lower? Higher?

[ 12-30-2004, 05:15 PM: Message edited by: KallyI ]

[Peter J. Bierman]

Is this pressure messured on a aftermarket gauge or on the onboard gauge?
On board systems are known to be not very accurate.
Either way I would not worry about is if it has been that way since new.

Peter

[KallyI]

Is this pressure messured on a aftermarket gauge or on the onboard gauge?
On board systems are known to be not very accurate.
Either way I would not worry about is if it has been that way since new. This is, and always has been measured by the factory gauges. I do realize that they may not be giving me the absolute truth, but relative to themselves, they will be truthful. In the 8 years I have been driving the truck, they have been consistent in their indications, so while they might not be accurate to the 3rd decimal, as a trend, they serve well. I suppose I am wondering what the acceptable indications on my factory gauges might be, considering that there might be a margin of error between my factory gauges and anyone else's factory gauges, maybe up to 20%? :confused: . If 20% is in fact true, my oil pressure at idle would be any where between 32 to 48 psi, and at speed, between 56 and 84 psi. I am not sure what GM says the oil pressure should be at idle, and at speed.


That said, 45 psi at 2000 RPM is plenty of pressure for these engines. Any more is a needless load on the engine and can contribute to oil consumption in the turbo. My truck has consistently used about a liter of oil between changes (usually 3000 miles intervals). Sometimes it's a bit more, sometimes a bit less. So is my pressure too high? It's hard to believe that the factory gauges would be out 45%, but I suppose it's possible.

[Peter J. Bierman]

Only way to be sure is plumming another gauge into the system and see what that reads.

Still would not worry too much about it.
You have plenty oil pressure and if the engine is running fine it's OK.
Checking would not hurt anything though ;)

Peter

[Govt issue]

the rule is on any engine you need 10psi for every 1000rpm . the higher the better. 3400rpm 30 to 40 psi.

[cruzer]

KallyI, IIRC GM's min at idle is 10psi. My mech gauge reads approx 18psi at idle and my stk gauge reads somewhere around 30psi, if I recall. I don't pay much attn to the stk gauges anymore.
At over 2000 rpm they both read around 40 psi.