I idle at practically zero oil pressure and go up to around 30-40 when Im driving. What can I do to fix it?

 

Put a mech gauge on it and make sure. I had the same problem. The factory oil press gauges are crap. I even tried changing the sending unit and it didn't help. It is in the dash cluster/instrument.

My oil press was great with the mechanical gauge. So I took it back off and just don't worrie about it.

 

Well I had this engine in another car and it read the same so I think it might be the engine? Unless both guages are both reading it wrong the same way??

Ill try and get mech gauge on it and check it

 

yeah what vxturboxv says. When you get a new gauge, reading should be around 20 at idle and around 60 at cruising.

 

its a little low, but definatly be sure to put a mechanical gauge on it. some engines pull as much as 35psi at idle, my SE pulls between 25-30. my other 85 GSL pulls 30 all the time. but those are stock readings and i would suggest getting a mechanical gauge.

 

can you guys please confirm colour of wire going to oil pressure sender unit

 

Check your oil and see where the level is. My guage has always read fine. The other day I was on the interstate going about 70 and my oil preassure was only about 55 or so. So when I got to my cousin's house I checked the oil and surely enough I was just below half

 

the wire should be yellow with a red stripe. it has a blade connector on it.

 

Ok, same problems here for me, but 0 pressure was originally seen with the factory gauge, (assumed all was ok and sender just bit it). Now I have installed a digital dash and put the oil pressure sender in the RB block for the oil filter pedestal, started the engine and it showed 14 psi (cold) then went down to 0 once warm (-2 actually). Nothing is acting funny, engine is running like it always has (before all of this came up) car builds pressure to about 40 psi or so under throttle. Any ideas? I'm assuming the worst, but how long could the car run like this (already done 2 autox events on it this way already without a hiccup). What's next to check...

 

heres what i did

https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-atempt-aftermarket-oil-pressure-gauge-539849/
i get 20psi to 65-70 when its reving high enough
i was freaked about 20psi but as stated above its ok phew

 

Thanks for the input, but i have the Racing Beat oil pedestal adapter, and using my new sender installed there, i still get no oil pressure at idle, but it builds with throttle. Anyone else have any ideas? I did put teflon around the sender, so i may try to take that off and see if that helps anything (if that is interrupting the ground for the sensor or causing resistance to ground).

 

My guess is you kept the same sending unit, which should give the same reading as before. clean, change the sending unit or go with an aftermarket unit.

 

Trochoid the legend, that makes so much sense.

 

Yeah, perhaps for him, but with mine it is an entirely different sending unit and a different gauge (my mxl pista). Idles at 0 (-2 actually, is that even possible?) and builds pressure to like 40 or so. Any help would be greatly appreciated.

 

well if its a like myn and has a hose to the gauge you may have over tigtend the nuts and crushd the little cipper washer things

well acutally itl probaly cause high pressure hmm just a thought

 

Not familiar with the digital gauges, you might try a mechanical one to verify the reading.

 

I guess that is next, but theoretically could there even be a negative oil pressure reading? The car does not smoke at all (except for like a second or two at startup) and runs smooth as a baby's bottom at all other times...very weird.

 

Remove the Teflon tape and check it. The gauges (stock or aftermarket), measure the oil pressure through resistance. Normally, the resistance goes down with increasing pressure. The Teflon tape is probably adding resistance and shifting your reading down (like a -25 psi offset). If it still shows the same after removing the tape, try a mechanical gauge. If it shows the same, possibly the o-ring in the front cover blew out (low to no pressure at idle, some pressure at higher RPM).

 

well, removing the tape didnt change anything (except now I have discovered a coolant leak at the waterpump/radiator hose connection). Guess a cheapie mech gauge is next, before diving in to the front cover o-ring replacement. Anyone know of the part numbers needed for that? I saw the FAQ on MazdaTrix's site, but they don't list part numbers or anything, and that was for an 86-on front cover, and mine is 85, is it the same thing? I was gonna drop the pan anyway to install the baffle plate, but hadn't figured on this.

 

If the o-ring on the front cover is blown, the bearings don't last long at all. Since you are getting oil pressure at higher rpms, I doubt the o-ring has blown. Another causes could the front oil pressure relief valve is sticking, which can be checked with the pan off. While the pan is off you might think about modding the rear oil pressure regulator to increase the oil pressure.

 

hmmmm...what would unstick the relief valve? or is it a replace kind of thing? I have run the car at two autox's (that is the primary use for this car) without anything going horribly wrong or funny noises, just thought the gauge sender had gone bad, and wasn't too worried. Well, i guess now I have something else to check.

 

UPDATE:

Ok, i have now confirmed the low/no oil pressure condition at idle with a sunpro mech press gauge. LAME...So my other questions are still unanswered, can i "unstuck" my oil pressure regulator? I will be dropping the pan now I guess, so i will install my baffle plate while i am in there. Are there any part numbers for the front o-ring fix (gaskets, o-ring etc.) I am amazed that my car has been ok for so long (some street driving and 2 autox events at high rpm with long waits in the staging area at idle) with this low/no oil pressure problem. I have the racing beat oil pedestal adapter for two gauges, temp and press, would it matter which side of the pedestal each gauge was installed in? I mean, i assume that pressure will be in the system on both sides of the pedestal... Also, is -2 a possible pressure reading for the oil system (indicating vaccuum???). Thanks in advance guys.

 

No. Negative oil pressure is not possible because there would have to be a pump sucking oil out of the eccentric shaft.

Take a good look at how the oil ring land looks on your engine. You may be able to use a soft copper crush ring as a gasket instead of an o-ring. When you do this, do not use a front cover gasket. Just use RTV. Make sure you do not use too much aroundt the area with the small hole that feeds the OMP.

While you have your front cover off take the front oil bypass off and check the plunger. Clean everything up and ensure smooth operation. Use two 1mm washers as shims for the spring and reassemble.

If you can get your hands on an FD oil pressure regulator I would highly recommend you use it. Your engine will thank you for it in the long run.

Never drive your car if you suspect a low oil pressure condition. Our engines are not very forgiving when it comes to oil starvation.

 

so on my 85, im about 25-30ish at idle, goes to like 60-65 when cruising.
my friend on his 85 stays between 60- 65ish, idle or cruise.
gonna get a tester for next week to see whos is right or what the deal is.
for being the same cars, ours are so damn different its not even funny.
to be continued...............

 

Your oil pressure is within oem specs, he may be the one with the problem.