YES, I SEARCHED.

Now, help me diagnose my low oil pressure problem...
Here are the symtoms:
Upon startup, when the car is cold the pressure is good, goes up to about 70-60 psi at 3000rpm and 30psi at idle like it's supposed to.

Once the car warms up it starts to drop and looks like this:
15psi idle
50-55 psi 3000rpm
60 psi 4000rpm

What would cause it to fluctuate like that depending on engine temp? I guess that is the oil viscosity changing, it thins out when it heats up, right?
Why is it so low at idle and just a little bit low at 3000rpm?

Sooo, front cover o-ring or oil bypass thermo-pellet-thingy? Or both? Something else?

The car is a streetported 87TII, rebuild about 9,000 miles ago. Valvoline VR1 20W50 oil. I just yesterday installed a Defi electric oil pressure gauge and all those^^ readings are from it.

 

Sounds like the E-shaft thermo pellet

 

How do the new pressure gauge readings compare to the stock gauge readings?

Where did you tap in for the new gauge?

You've got the bypass pellet installed (probably on the rebuild), right?

 

The new pressure gauge reflects what the stock one was telling me, I was hoping it was just a bad sensor. The new gauge sensor is in the location of the stock sensor.

I didn't do the rebuild and I can't get ahold of the guy who did, so who knows on the thermopellet.

 

Soooo...... the thermopellet?

 

Are you really worried about those pressures? Other than the 15 psi at idle, those numbers match mine after the bypass was installed on my rebuild also. You've got a stock regulator that dumps at 60-70 psi, so you're not going to get 'em any higher. Used to cruise at 60 with the OEM thermo pellet, now I cruise at 55-58 psi with the pellet installed. It's not bothering me any...If you give her just a bit of gas above idle, do they return to 30-ish?

And I think if your front cover o-ring was shot, they'd be a lot lower across the board...

 

I agree, front cover O ring failure will lower oil pressure at higher RPM, not at idle.

The pressure is only low at idle, I would be also looking at oil type and quality and oil filter type.

 

Are you sure it wont lower pressure at idle? My front cover o-ring got pinched when I put the cover on and slipped out causing me to have 0 psi (stock gauge) at idle. Replacing the retainer/o-ring gave me 20-30psi at idle.

 

Yeah, if it is blown out entirly it will act like yours, but he has normal oil pressure at 3K which suggests the O ring is fine.

Been my experience if the O ring was just leaking or the wrong gasket was used, then typically you get normal or just below normal oil pressure at idle, and around 45 psi around 2K RPM, but further lower at each RPM (3K, 4k and 5K and up).

 

Ah, gotcha.

 

on my fc oil pressure at idle it a little above 30 and crusing at about 3.5KRPM it stays at 60. normal right?

 

is your car buning more than normal amounts of oil? or does the oil on the dipstick look burnt?

 

Yeah, when I hit the gas it goes right up.

If there is nothing wrong with it, that's fine, I just don't want something serious to happen because I didn't fix something. You know what I mean?

So you guys think I should just not sweat it and try some different oil filters and such?

Thanks for the replies.

 

I run premix, OMP is blocked off.

 

Yes, normal

 

Yeah, unless you're routinely racing and/or keep high loads on the engine, I wouldn't worry about it.

I'm going to do something about that damned bypass pellet when I do the next rebuild, because I'd rather see 60 psi also

 

... going to check mine tonight. i thik im getting 30 at idle and it was sitting at 30 when it was around 3.5k..

 

If the thermopellet or front cover oring was indeed the issue wouldnt oil be leaking out of the front cover noticeably?

 

I've seen a few sevens with the front cover o-ring problem. Only a couple had a noticeably amount of oil on the front of the front cover. Now when the front main seal starts to leak, then theres a mess in the front of the engine. I have never personally experienced a thermopellet failure, and I dont intend to on my next rebuild...thermopellet plug from mazdatrix.

 

no, there could be 0 external leakage.

 

^Thanks