Super high oil presure after oil change?

[Nissan_Boy85]

So yesterday I changed my oil, added brake fluid, etc. and kept glancing at my oil pressure gauge on the drive home from Portland. No problem there. I glanced at it this morning headed to class and the gauge was about freaking maxed!!! It was reading about 90 psi. Got a bit farther down I-5, and it was reading normal preesure, and it continued to the rest of the drive. It seems to do this untill the motor heats up to a sertin temp. What the hell?!

 

Oh, I knocked my temp gauge sensor wire off and haven't put it back on yet. That couldn't cause this, could it?

Edited November 22, 2009 by datzenmike

[datzenmike]

Is this after market gauge? Maybe the wire is grounding against something causing a full reading. I seroiusly doubt it's really making 90 PSI.

 

Only way you can get pressure like that is if the pressure relief piston in the pump jams and won't move back against the spring. I had this happen... it blew the filter apart!!!

[Edz280zx]

My L28 with the turbo pump makes about 90 when it's cold..then it settles down to about 70 or so at normal rpms...rev it up to about 5k and it goes up to 90.

[Jayden71]

My L16 makes 85psi when cold, after about 20mins settles down to 50-60.

I got new bearings and oil pump tho:D

[banzai510(hainz)]

try another oil filter

[Nissan_Boy85]

Is this after market gauge? Maybe the wire is grounding against something causing a full reading. I seroiusly doubt it's really making 90 PSI.

 

Only way you can get pressure like that is if the pressure relief piston in the pump jams and won't move back against the spring. I had this happen... it blew the filter apart!!!

 

Stock gauge out of a 85 4x4. Aftermarket sensor. It's deffently making more preesure then it normally does though, my valve tick goes away when it's reading super high. I'm gonna double check the filter part number tonight.

[datzenmike]

The oil pump has a pressure relief valve in it. When the oil pressure builds on the filter side of the pump a small piston is forced against a spring. As the spring compresses under the piston an opening in the cylinder wall hidden by the piston is exposed and the oil vents out and back to the pump inlet and the pressure is reduced. A blocked or incorrect filter has nothing to do with the pressure except lack of pressure if the filter fell off. A stiffer spring will cause higher pressure. Cold oil will be thicker and have slightly higher pressure at idle.

 

Unbolt the pressure relief cap and remove the spring(s) ... is the piston free to move in and out or is it stuck? In my case I had just done an oil change and started it up to check for leaks... it was normal. Next morning I drove 5 miles to work on the highway, pulled in to work oil light on, filter split open. Replaced the oil and new filter and everything fine, drive home, oil light on, filter split open again. Pulled the oil pump and found a tiny piece of casting jamming the relief piston so it couldn't move. At idle the bearings leaked the oil as fast as it was pumped so the pressure was fine, but when revved up the pump overcame the losses and the pressure went up and would blow the filter.