I already did a complete oil change and checked the gauge by replacing it with a mechanical one. right after replacing the gauge the car had perfect oil pressure and idle (almost never happens). I let it sit idling for a good 5 minutes playing with the throttle a bit and saw perfect oil pressure entire time. five hours later I actually drove it.

I drove it 20 mins and then got out and checked the gauge under the hood and it read 0 at idle, but it read normally if I reved it above 2500 or so. I'm thinking my oil pump is bad at this point, anyone have ne other ideas? Also I was wondering if I could premix in the meantime.

 

I forgot to mention I have a manual 88SE that's bone stock.

 

Your OMP wouldn't affect your oil pressure to that point. It just throws a little oil into the chamber to help lubricate stuff. It's not the main lubrication system in the car. As far as my understanding...

 

Several possible causes:

1. O-ring in front cover blew out. This allows most of your oil pressure to just spray back into the pan.

2. Oil bypas thermostat in front of eccentric is stuck open. This allows oil to bypass all the oil jets that spray into the rotors and will lower oil pressure.

Either way, the front cover has to come off to diagnose either problem.

 

thanks Aaron, now I know what to look for when I open her up.

 

ok got down to the step of removing the front eshaft hub (haynes manual) and I can't for the life of me get the bolt off. I'm using a chain wrench and a 2 foot torque wrench. The chain wrench slips even after I attached it using chanellink plyers. I've completely drowned it in wd40 and tried tapping it with a hammer.

 

You need a impact wrench, and sorry to hear man!

 

Take a couple of days off and read Gnome's "battle with the front bolt" thread...Can't remember the title now, just that it turned into a book of 30 some-odd pages...Lot of good info in there, though...

 

how many ft/lbs are we talking? and why does the haynes manual say u just need a chain wrench and a ratchet?

I'll go look for that thread. I was kinda hoping to get this thing moving for college, but I think it's too late for that now.

 

hah, got it off with the alternator trick. now I see somethin' very small laying in a pool of oil underneath the eshaft....... I did keep the clutch engaged when doing this, but I did let it go once the nut was loose so I could put a log in place of my leg.

 

got the front part of the engine completely dissasembled, front cover and all. oil pump looks fine (how do I check if it works properly?), and it seems like there's no way for this thing to fail. I have no idea about that oil O-ring I was looking for, only found the front shaft one which seems in excelent condition.

 

well i have read a few threads and ive noticed a few people with the stock oil pressuer gauge has a problem that once car is warm it idles at just above 0 and then it goes up to about 2 - 4 on the stock gauge...

Ive got this problem and ive just purchased the car and i was scared, i went out and bought a autometer electric gauge and still the same, was weird.. this is with a new sender that definately matches the gauge...

still scared i hooked up my mates mechanical gauge and beautiful, idles at 20psi and goes up to about 65psi under load, so there is no issue.

What is causing this improper reading from the stock gauge, is it the sender, the gauge or the whole electrical system?

OMP wont affect oil pressure.

Im getting good pressure so my front o ring cant be gone though i have a small leak around the omp somewhere i have to find...

Like i said i remember reading a thread and it had a few people with the same problem, so quite obviously its a known problem and is most likely something small.

Anyone!??!?!

andy

 

update: O-ring was where it shoulda been, my gasket broke off instead of came off so I had to do some scraping and will replace it with silicon gel as per mazdatrix instructions. The oil bypass valve was closed, and it opens .34" instead of .24" as per specifications at 140F. Oil pump has no visible signs of wear. Oil pressure control valve is good, spring has correct free leangth. so......... wtf was causing my low oil pressure? what else should I check before just reassembling this thing and hoping somethin' just fell back into place.

 

usually the most common cause of a low oil pressure reading on the oem gauge is a dirty connection on the sending unit :p

the unit is located right below the oil filter, so it is subject to all sorts of crud accumulating on it, which can create a bad connection.

as far as the mechanical gauge goes, it shouldn't lie...i would double and triple check the installation

It's very rare that the oil pump goes bad on these cars

 

I know the oil pressure was low cause I could hear a mechanical scraping sound on engine breaking, which was not there when the oil pressure was fine. I made a closer inspection of the thermal pellet and realized it does indeed stick open. but since it opens when it gets hot how could this cause a low oil pressure when hot like everyone says?

 

The thermostat may not be opening in the engine. You've pretty much eliminated everything else.

 

FD's have a problem with the stock gauge reading incorrectly due to a bad connection... won't read down low at all (shows "zero" at idle) but just a blip jumps up to 25 or 30 psi. FC's might get that same problem

 

My car does the same thing with the oil gauge reading near zero at idle. Its done this pretty much since I had it rebuilt, and it now has almost 15k miles on it with a good break in. The guy that rebuilt it is very good, from what I heard, so I assume everything is alright. Also, it still runs fine, and doesn't seem like its lacking lubrication. I wouldn't worry too much about it.

 

Yup my exact problem as youve explained, i know i have oil pressure there so im not too stressed im just worried about one day if i suddenly lose pressure i might not notice it and keep driving!

:/

 

Same thing with my 88 GTU, just notice it was low last week while chasing parts for our Jeep CJ. Did a search and decide front cover oring must have failed and torn down front of motor. oring was still there but very flat (1.5 mm-gasket is about 1mm) don't know if that is it or not. free length on oil press spring is 71 mm a rch short. Going to order pellet kit and reassemble.???????

 

Everyone with a low oil pressure problem NEEDS to verify with a mechanical gauge first. If oil pressure is low, then it will be caused by one of the problems I already mentioned.

Here again, are oil pressure problems.

1. Oil pressure is fine, defective gauge/sender.

2. Oil o-ring in front cover is leaking or has blown out entirely. When assembling a new
engine, the Mazdatrix FAQ on this MUST be followed or you could have potential o-ring problems. O-ring issues are characterized by low or no oil pressure at idle, which creeps up close to normal at high RPM.

3. Oil thermostat in e-shaft. Can cause all mannor of weirdness, but normal failure is to stick and cause generally low oil pressure (all pressure bleeds out the front of the e-shaft). Very common. Should always be replaced with a pellet when an engine is assembled.

4. Oil pump sprocket slipping. Under VERY rare circumstances (normally a fault during rebuilding), the key that locates the sprocket on the shaft of the oil pump can shear/fall out. This causes the sprocket to slip on the shaft, resulting in very little, if any, pressure. VERY, VERY rare.

5. Even more rare, the oil pressure regulator can stick open.

6. Rarer still, the body of the oil pressure regulator can fall off it's threaded base. I have only ever heard of this once, never seen it. Happened on a car that was seeing constant high PRM operation at the track. Don't even consider this an option.

7. Broken oil pump chain. Never heard of this actually happening, but it could. Result is zero pressure.

 

im marking this one for my next year to do list...

 

I have oil pressure, so its something to do with guage or sender... going to check that there is definately 12v at both this weekend!