We have experienced low oil pressure (5-10psi) at idle after warming up and 10-20psi at 2500rpm. At 3500 rpm we are up to normal -- 30psi or above. Engine has 100K miles on it and otherwise normal -- 1 qt oil consumed in 7k miles. Suspect 1) worn bearings, 2) leaking oil pressure relief valve, 3) defective gauge (our hope!). Has anybody experienced similar problems?

 

I was under the impression that 30 PSI at 3000 and 60 PSI at 6000 was the norm.

Rat

 

1 quart in 7000 miles??? that's REALLLLY low!! Your car should be consuming a quart aobut every 700-1000 miles. Suspect your oil metering pump, or that pellet thing i cant think of the name. Anyway suspect something bad, it should be eating more oil AND have a higher pressure.

 

1) failed o-ring under front cover, very common on 86-88 models
2) failed oil thermo bypass pellet
3) failed sending unit/gauge (the fact that it moves around and gives a semi-accurate response to throttle means this is unlikely to me)

Rotary bearings do not normally wear out until well over 200k, if maintenance has been done.

Oh, the 1at/7k miles is pretty low. It is normally 1qt per 2000 miles or so.

NOrmal oil pressure, for a really tight engine, is 60 at startup, 30 at idle, and 50+ at cruise.

 

my 89GXL has 30 at cruise 50 or so at cold start and just under 30 at idle. This is normal for me I believe.

 

Did it happen all of the sudden? If so, I'd just go straight ahead and take the front cover off. There's a very good chance that it's the little o-ring in there. Don't worry, it only costs 1.90 at the dealer (don't ask how I know that...)

Good luck!,
Manolis

 

Any rpm above 2000 RPM should normally be around 60psi

 

60psi??? I think your thinking of turbo models. Dont they run higher pressures ?

 

same pressure... but they all run 60 at 3000. not 2000.

15-30 is norm for idle.

 

so what should I do since mine does not run 60 at 3000? I mean it will if I stomp on the gas to 3000 but thats a big load.

 

buy a new gauge

 

ok , but does anyone know why the oil pressure goes to 0 only at idle sometimes??? Is this my gauge to scott89?

 

Like they said, about sixty when scootering down the road at sixty or seventy. Zero at idle makes one think of the 0'ring in the front cover, maybe the thermopeller in the front of the eccentric shaft.

I think its a BIG mistake to pull the front cover off until you determine if the oil pressure is really low. The factory gauge does not count. Get a MECHANICAL gauge like a SunPro from the PEPBOYS or Autozone and install it temporarily. THEN decide if its really low.

NOTE: See how the factory manual uses a mechanical gauge to determine the oil pressure. They must know something about the factory electrical gauge. Not a joke.Not humor.

P.S. Send me your oil sending unit and I can make it read whatever you want it to read.

EDIT: See the factory manual in the electrical section for a method of checking your dash oil gauge for accuracy.

 

"I think its a BIG mistake to pull the front cover off until you determine if the oil pressure is really low. The factory gauge does not count. Get a MECHANICAL gauge like a SunPro from the PEPBOYS or Autozone and install it temporarily. THEN decide if its really low.

That should have been the first post to this question! What gauge are you using to determine the pressure is low?

James

 

My stock gauge. Unless it just goes inacurate all of a sudden otherwise It has been reading well until just now.

 

If the front cover O-ring starts leaking you will get considerably lower oil pressure with higher RPM, while just slightly lower than normal at lower RPM, so just popping open the front cover can be a big mistake if you are not sure.

Trace down the problem before you start pulling things

 

Why is everyone so against poping the front cover? Why is this bad?

 

A bit of a hassle, if you ask me. There's the deal that can become a big deal, with removal of the 19mm bolt(WRENCH SIZE) that holds the eccentric shaft pulley on. Should have been installed with locktite and sealant, plus a good amount of torque. You have to restrain the eccentric shaft from rotating while you try to bust that bolt loose. Then you have to be careful not to dislodge some bearings (darn, forgot what those needle bearings are called{thrust bearings}.
And you have to remove the water pump, oil metering pump lines blah, blah.

And then you find everything is just hunky dory when you get it off.

By the way. Follow MAZDATRIX advice and don't use the cover gasket when reinstalling. Just use RTV. But don't accidently block the oil metering pump feed hole on the middle left side of the cover.

That said, I have had a bad 0'ring under the cover. It was on the first 13B I'd done and was confused about what was going on. Seems MAZDA gasket kit did not have the correct front cover gasket and I was trying to use one that will not ever work since it was meant for a later housing, not mine. See MAZDATRIX, FAQ

 

thnx hailers. By the way my mechanic took off the front cover a long time ago because the gasket went out and sprung an oil leak . It only cost 280