My 12a 85 has 70k on it. Runs great, oil pressure is barley above zero at idle and around 50-60 range at 4k cruise. Is this normal? I'd like to bump up the oil pressure a bit. Could someone explain how to do this? (i'm useing the factory gauges which could also be off)

Thanks alot

 

single digits @ idle is very bad. it should make 20-35psi @ idle. when wa last oil change?

at 4k it should make 70psi stock. if oil is very old and thin that could be it. Or bearings are very worn......

If you have an oil pressure regulator from pre-80 then put a 1/8" washer in there and it's shimmed, will make 85-90psi. Otherwise buy the one from racing beat. U gotta drop the pan to put the rear pressure regulator in there.

 

I would test your oil gauge first. The one in my dash went down and I thought It was the oil pump. Nope, just a bad gauge. Give it a try.

 

Oh ya, if you want to shim a pressure regulator you will need a 76 or newer regulator.

 

The regulator won't do squat to oil pressure at idle.

The oil pump will pump a fixed volume of oil per revolution. The oil goes to the bearing journals and bleeds out from there, which is fairly constant independent of RPM. Resistance to how quickly it can flow through the passages and out the bearings causes backpressure in the system and this is the pressure that you're measuing. The regulator only serves to *limit* how much pressure can be developed.

So at idle and low speeds, the regulator is slammed shut anyway, the full output of the oil pump is going through the bearings. This isn't really a problem, and I wouldn't worry about it.

Might want to remove, clean, and replace the pressure sender. The engine in my car would register nearly zero at hot idle, about 45 max at hot cruise, before I took it out for something else. When I put the thing back in, re-installing the SAME sender, it now shows up to 80-90psi on a cold (~20degF) engine at any RPM, about 60-65 on hot cruise... but still about 15 or so PSI at idle.

With bearings as big as we have, you don't need any pressuruzation at all until you get into the real high RPM ranges, and then you're using it to keep the E-shaft stable. But oil *flow* across the bearings keeps them cool, so we pump goodly amounts through, and of course there are the rotor spray jets.

 

and this is how to make it...using stock rear plate, hammer and your stock ROPR.


Left is stock..Right is 100+ psi.


this will give you 30 at idle and 80 above 3K rpm

 

nice i think i might have to do that tomorrow i have like 2 extras

 

How do I test my oil gauge? Is there a resistance/OHM test? Or should I just hook up a mech gauge? Where would be the bes tplace to hook up a mech gauge.

As in 1976 and newer? My car is an 85. 'Im new to the rotary game, pls explain what you mean by "76 or newer regulator"?

Sounds like this could be my problem. I really doubt this engine is worn it has 70k miles on the clock and about 40 or so were tow miles on the back of an RV. Where is the sending unit on the 12a's? I'd like to try this first.

As far as modifying the high RPM pressure I don't think it's necessary for my needs. I won't be reving it real high this is just a daily driver. Unless it is reccomended for daily driving?

Thanks all! Really appreciate all the help!

 

item "N" on this page: http://www.mazdatrix.com/boil2.htm

it's located on the rear side housing, below the oil filter

 

Mel, did you just hammer the stock regulator from cone to flat?

Thanks, Ed

 

yep.

By the way, I'd hook up another aftermarket gauge 1st if I was you.
My dash oil pressure gauge is no where near accurate.

 

Ed
If you hammer it flat like the above pix, the spring will be too stiff and you will end up with above 100 psi.

The other pix, installed in the rear housing, is an 80 PSI. yeah, the clarity is no good. If time permit, I will make another one this weekend.

 

yeah, my FB read near 0 at idle also. but it was the gauge mazda oil press gauges are pure crap!!!

 

Peejay, great info.
Wackyracer, thanks for the how to!
VXturbovx, when I said 76, I meant 1976. The ealier pressure regulator come apart and can be "shimmed". As far as testing your stock gauge, I would try an aftermarket guage like DirectFreak suggested.

 

Check your oil pressure SENSOR (little mushroom shaped thing on the rear housing just south of the beehive). I drove around for a week barely wanting to touch the accelerator because I thought my oil pressure was pegging past 4kg/cm2 every time I stepped on it. Then it went dead for a week, and I traced the problem back to a loose/dirty attachment on the oil pressure sensor. There is only one wire for it, and if the connector isn't connected well, you'll get different readings because IIRC the reading is based on resistance. Improper connection, more resistance!

So check them wires!

Jon

 

I removed the wire, sanded down the grime to shiny brass on bothe the connector and the press sensor and I get the same thing. About 60psi at 3500-4000 cruise and maybe a 16th of an inch past 0 on the gauge at idle after the car is warmed up? I'll replace the sensor this weekend. Then I'll go for the mech gauge. Hope this low mileage car doesn't have oil press problems!

Thanks all!

 

The two vertical ones are pre-80 or old school RX. I usually shim it with a nut to gain higher oil pressure.


left is stock. right is 80 psi (slightly hammered the tip)

 

And I do have to take the front case off to get to that right?

Ok so I replaced the sending unit and still get the same thing. My gauge doesn't sit directly at 0 with the power on is that normal? Sits like it is in the PIC. Once Im competly warmed up at idle my oil press sits aprox where the yellow needle I drew in is. Is that to low?

Also I noticed if the car has set overnight or for several hours and started completly cold (always starts up the first crank) I get a pretty large cloud of smoke (oil) Sometimes it's alot and sometimes it isn't. Is this normal? The car doesn't smoke at all after that. I had my girl friend follow me on a 6 hour car ride and she said it didn't smoke at all.

Thanks!

 

you have to remove the oil pan to change the ROPR.

Add a mechanical oil pressure gauge for a much more accurate reading. Also, if changing the sender/wires doesnt fix the 0 oil pressure, you may need to change the entire clutster. Thats what I did to my new FB.

 

Well, I hooked up a mech gauge and after a long cruise sitting at idle for 15 min I was at 35-40 psi. And mid 80's at around 6 k. So it has to be the sending unit. Anyone know of an alternate sending unit that is compatible with rx-7's? None of the local parts stores carry it and I'd like to get one today.

Thanks

 

Found a sending unit suposidly for my car. Now it just sits at 60 at idle and barley ever moves? Can't seem to figure this crap out? Also noticed theres a pressure switch for the AC tied into the signal wire going to the gauge. If I unplug that Oil pressure sits about where is is suppose to 30-35. But then as I rev it doesn't move much at all maybe goes up to 40 at like 7k rpm. Everything checked out perfect on the mech gauge anyone have any ideas?