Welp, not sure whats going on. My 1987 Rx7 TII has low oil pressure

I noticed after a warm start that the oil pressure was 10 at idle, and giving it a little rev, I will get to 40-50, driving at 3k rpms is mid 30s.

• No major leaks, small one here and there around the pan, one by the filler neck.
• No smoke out of the tailpipe
  • Makes me think the turbo isnt eating it
• Oil level seems fine
  • Honestly hard to read, ill check again in the morning after letting it sit
• Oil smells slightly of fuel
• 2500 miles on oil

Never had pressure issues before. I do have a Racing beat regulator installed.

What would be the culprit? I dont think the oil pump would just go out in the matter of a day. Maybe the strainer is plugged, or what if the fuel is diluting the oil. If so, why is there fuel!

 

oh, and the pressure readings were done through my aem meter, not sure how often the sensors go bad on those if ever

 

The Mazda FSM specifies 64-78 psi at 3000 RPM at normal operating temperature. I usually change my oil & filter at about 2500 miles using Castrol 20W-50 oil. The oil in the rotary typically sees some degree of dilution from gasoline during its useful lifetime. The dilution lowers the viscosity, which will lower the oil pressure.

I have no experience with the AEM sensing unit. A mechanical gauge is always your best bet for accurate oil pressure measurement.

I would also check the following:
1. Oil cooler lines and/or oil cooler for leaks,
2. Oil filter pedestal o-rings for leaks, and
3. Front cover o-ring failure can drop oil pressure, which would require removing the front cover to get to it. Not a simple task.

 

front cover o-ring plausibly it would be a non visible leak so to speak, otherwise the small chance is that the oil pump went bad. a gerotor design works great but if its all scarred and worn it will have loose tolerances and give you low pressure/volume

 

the other possibility is a bad thermal pellet in the E shaft

 

All right fellers and fellets, I have some more info for you guys..

• 10k miles on engine
• Atkins solid thermal pellet
• Verified no visible leaks at the oil cooler or pedestal

I hooked up a mechanical gauge to my pedestal today, and also changed the oil with new 20w-50. The pressure was about 60-50 when starting the engine cold, then slowly warmed up, and still reached 10psi. The engine was warmed up to operating temp. At 3k rpm it was 65-70 psi, which is to spec, so its only at idle where its a little too low (idle being 1k rpm).

There was a point with the electrical gauge that I saw 2 PSI, IDK if this is true or not, I shut off the car immediately, I am going to see if I can replicate it with the mechanical.

What are the symptoms of a failed oil ring in the front cover? Im thinking about retiring the car for the year and pulling off the front cover, verify the oring is in tact. Whats this I hear about using an RX8 gasket? I need to find some posts on that.

The only mod to the oil system is the Racing Beat Street pressure regulator, and the odds of that being busted are slim.

My pump could have gone south, the pump has about 110k miles on it, but I cant imagine it is something that fails darn near overnight, and I feel that there would be less pressure at higher RPM.

Not getting blowby on the engine, the analog gauge would have been pulsing then, and I imagine I would have more oil pressure then.


Welp, there is what I know for now, really dont want to pull out an engine, my LS loving coworkers will give me crap. But if it is out I could stud and port it , never mind that, need oil pressure

 

i don't think there is necessarily one set of symptoms because it will depend on your o-ring situation (damaged, out of place, missing altogether, etc.). the common theme, however, would be some sort of low, or dropping, oil pressure.

when it happened to me, my oil pressure appeared fine at idle and would rise the way it should with RPM, it's just that whenever i was cruising (RPM sustained), i would see it start falling. it took me a while to figure it out because i had modified a few things in the oil system on that particular engine when i built it.

i have yet to try one for myself, but from what i hear, the Rx-8 is just better all around. it requires some minor trimming though.

here are some links:
https://www.rx7club.com/naturally-as...essure-889778/
https://mazdatrix.com/product/gasket...ver-04-08-rx8/
https://mazdatrix.com/86-92-front-cover-o-ring/

 

Update for everyone. I called a few rotary shops, they said 10psi at idle is fine, and that most race engines only have 5psi. So that's good! But, I took it out for a drive today, and while it was making 65 psi at 3k, after 2 blocks, it was making 45psi at 3k. It seems as though I have an issue. I guess I will be plucking the front cover to see what's up.

What if my oil pressure regulator became loose? Or the oil pickup tube became loose? Either way, car is getting trailered back to my shop, going to drop the pan and front cover. I hope I dont have to take the engine out. Im pretty sure my bearings are fine, they are all brand new, and I did not see any glitter/copper in the oil change I did. Ill post my findings. In the mean time, if anyone has ideas, let me know!

 

Another update and idk if it’s a good one. Still haven’t got to the oring, but dropped the oil pan to find this inside.


the black stuff is super thin and fragile, think it’s from my pan, rust or something. There was one flake of metal in the engine. 10k miles on the engine, new housings, bearings, and irons were lapped. The flake is magnetic, so I think it has to be from the irons. I maybe didn’t clean them well enough when I got them. It could also be from something else, I’d you know let me know. Would you be concerned with the flake?

 

Well, it’s the oring.


also the Teflon washer was installed, the builder did that. It’s not supposed to be there on my engine. What an idiot.

I built the engine