jmporsche944

Hey guys,

So recently I was driving my car and notices at idle the pressure was dropping to below 1 bar (UHOH). I drove it home keeping the revs up, and changed the oil. I started the car it didn't have pressure for about 30 seconds then it jumped up. When it did jump up it went all the way to 5. After the oil warmed up it was still low when ideling (light comes on).

I know that:
1. It is not a loose connection to the sender unit, I hear the lifters when its low on startup.
2. It is nothing to do with the filter, it is a mahle filter with the anti drain back

Could the OPRV be stuck open, providing low pressure?

I have a video of the car revs/pressure that I will post a little later once i get it off my phone. Thanks for the help. (The car is an 87, should be the one piece valve).

Jeff

DDP

I would start with the OPRV. You could remove it and try cleaning it before buying a new one. Why did you decide to change the oil to solve the problem? Was it past time for an oil change? I only ask because that could possibly lead to the OPRV sticking from junk in the dirty oil.

eniac

Sounds like the little green(or red) o-ring seal on the end of the OPRV is gone.

333pg333

...you didn't change brand/Visc of oil at the same time did you?

jmporsche944

Just seemed logical to me to drop the oil, make sure theres nothing funky going on with it (coolant/oil mixing, really low for some reason, etc).

jmporsche944

Nope same as always.

jmporsche944

Ill check this out. Thanks!

m42racer

Remove the pressure sender and fit a known good mechanical gauge. If the pressure still acts up, as others have suggested it is most probably the relief valve acting up.

dmalo810

How many miles on the car? If the OPRV isn't it, it may be time for rod bearings. Hope for the OPRV.

RPHARRIS

Crank Pulley? If the crank bolt loosens up, you will lose oil pressure in the manner you describe. It happened to me once.

333pg333

I think you're responding to this?

"Remove the pressure sender and fit a known good mechanical gauge. If the pressure still acts up, as others have suggested it is most probably the relief valve acting up."

jmporsche944

130k. I have had the rod bearings replaced before so it shouldn't be them! (I HOPE!!)

jmporsche944

I feel like if the crank bolt loosens then it will just be low, it wont be 0 for 30 seconds at startup then pick up right? That doesnt seem to make sense to me.

jmporsche944

Whoops, I was responding to checking the o-ring on the OPRV. I doubt it is the guage as people are suggesting, I hear lifter noise when the guage is reading 0.

Josh B

If you need a spare OPRV to test with I've got one that you can borrow for shipping costs - just PM me your address. The other thing I would check if I were you is the oil cooler thermostat. Easy to get to like the OPRV. Just fixed oil pressure issues on my car where this thing was no good and I've got an 87 951 with approx 130k as well.