High Oil Pressure?

[crackerjacksle]

Within the last few days my oil pressure gauge has started showing unusually high pressure.
The needle used to always hover around the middle; 40psi, maybe a little lower at warm idle & a little higher (60-70 psi?) at higher rpm.

The needle is NOT PEGGED. But now it starts out around 60-70 psi and jumps to about 90-100 psi on acceleration.

I've got about 56k miles, run 10-30 Castrol & a Wix filter.

I'm not due for an oil change, but thinking maybe I should anyhow. Clogged filter? Bad sender? Ideas?

[Mechanical Mike]

Most likely a bad sender. It's pretty easy to change.

[1fatcat]

Yeah, the oil pressure sending unit is a pretty common issue with this engine. Not a big deal, very cheap if you replace it yourself. About $25 for the sensor.

[crackerjacksle]

Hmmm...

Put in a new oil pressure sender; no change. Changed oil & filter; no change.

Guess I'm just gonna live with it, but I'm puzzled what would cause it to go up???

[00Beast]

What brand, weight and type of oil (IE: Castrol, 10W-30 Synthetic) and what brand filter are you using? Try some seafoam through the crankcase before your next oil change, for about 100 miles. Should clear things out if there is something plugged somewhere.

[crackerjacksle]

Castrol dino 10-30 & Wix filter.

A mechanic friend said I should have used an AC Delco replacement sensor instead of the no-name I got from O'Reilly.

I guess I'll try that, but the fact that both sensors are giving me the same reading makes me think they're working.

He said the next step would be pulling the sensor out and hooking up a mechanical pressure sensor to verify the reading.

If it was accurate, the cause would probably be a bad bypass/relief valve on the oil pump. He quoted $400-500 for replacement, saying they'd have to drop the pan and pull the timing chain cover to replace the oil pump. Sound right? (I've only got 57k miles!)
He said from his experience it would be VERY unusual for a 3800 to have a bad oil pump & was betting on the sensor.

Here's hoping!

If the AC Delco sensor doesn't do it, I'm gonna try the SeaFoam, although I've never used it on anything before...

[Mechanical Mike]

You should try the mechanical gauge, that'll rule out both the sender & the dash gauge. The bypass valve is right behind the oil filter adaptor. Remove 4 screws and you're there, about 5 minutes tops once it's on the lift.

[2000Silverbullet]

With a mechanical OP gauge, how do you satisfy the fuel pump shut off feature? .....or does it default to a closed circuit?

[Mechanical Mike]

I don't believe it exists!

[00Beast]

I don't believe 00+ has the fuel pump cut off switch through the OP sender.

I agree with the mechanical gauge, as well. That won't lie about your pressure.

[myfirstbonnie]

With a mechanical OP gauge, how do you satisfy the fuel pump shut off feature? .....or does it default to a closed circuit?

Paul, I did some research on this, and the only way the oil pressure switch will cause the car to stall is if the FP relay is also bad. Here is where I posted my info that came straight from my 89 and 95 FSM's:

http://www.pontiacbonnevilleclub.com/fo ... =48&t=4515

I have not looked at those circuits in my 2k FSM yet.

[willwren]

Our cars are as finicky about OP senders as they are about bosch plugs and O2 sensors. I've experienced 'off-brand' problems with OP senders too. Get an AC Delco sender.