NoPistons -Mazda Rx7 & Rx8 Rotary Forum - Oil Pressure very low....oh, its in a plane

I continue to have a real problem with oil pressure. I have tried everything I can think of and, I think, everything that has been suggested here and elsewhere (nopiston, RX7 club, Mazdatrix, web and phone, Racing Beat) to no avail. My efforts may have increased pressure for a very short while but the pressure has not come up to proper levels (depending on which regulator, stock 2nd gen or the 100lb replacement I installed) nor does it stay higher. The new pressure regulator, rated at 100lbs, I installed brought the pressure up to about 70lbs for a very short while but has again dropped to a little over 20 at idle and not getting to 30lbs at 6000 rpm (only at 6000 rpm for a short while to determine if any progress, I do worry, especially about the PSRU-RDb). Oil is flowing as indicated by the system heating up.

This is a second gen, turbo engine.

Here it the list of what I have tried and some data points.

1. Yes, the front cover oil ring has been addressed, several times. I have replaced it a few times now, WITH and without the silicone ring around it. I have had it disappear, however, I have now installed a brass tube tapped and screwed into the engine to minimize the o-ring being blown out. I have checked this install to ensure it has not been restricting anything. It does not seem to be as I have run the engine, then removed the front cover and all was well, including the o-ring and silicone ring and it did not seem to hurt the iron or front cover.

2. The front cover does not seem warped or damaged.

3. I have replaced the rear pressure regulator with the 100lb version and modified the front bypass spring by placing the washers (2) provided by Mazdatrix.

4. I have verified that the oil pan pickup is not clogged and that it is securely safety wired to the engine and that the seal (no gasket but gray RTV) is secure.

5. I have replaced the oil pump with a new one from Mazdatrix.

6. I have verified the oil pump "key" is properly inserted and that the gear is secure and torqued properly and that the washer is bent as it should be. I don't recall if I applied RTV between the pump and block but I would think I did....this being the problem by oil seeping out is a stretch but I am considering all a can think off.

7. I have cleaned and inspected the stock oil cooler and it flows well.

8. I have removed the front secondary oil cooler that is installed in the front of my canard for cabin heat to simplify plumbing. This eliminated about four hoses as it was plumbed in parallel

9. The oil filter has been replaced with a new K&N 3001 filter. The remote filter mount has been checked and not problems are noted. I have also run the engine for a short while bypassing the oil filter to determine if it was causing a blockage as my oil pressure sensors located after the filter. The oil pressure did raise some, but only about 5 to 10 lbs.

10. I have checked that all the hoses flow freely.

11. The e-shaft was modified removing the stock spring to use jets for better oil flow. I remember verify their install at the last tear-down. I know this can reduce oil pressure a bit but nowhere near this much.

12. I purchased all the iron (end and center) and rotor housings new from Mazdatrix a while back.

13. The front and rear bearing have been replaced new. I thought maybe that they were worn (or damaged) but with talking with Mazdatrix they said they bearings would have to have much more significant wear than would usually be had in not competitive use. They said this was a very unlikely cause.

14. The original location of the oil filter is modified by the use of the Mistral intake that provides an o-ring seal and passage in place of the stock filter.

15. The turbo supply on the top of the engine and return oil passage on the front cover have been capped off as I have removed the turbo as I test the engine and until I can have produced a more robust turbo manifold as my first one failed from power pulses/heat.

16. I have had not noticeable leaks from the engine.

17. I wondered if perhaps I left a seal off somewhere during the last rebuild. I thought perhaps the o-rings that go around the dowels that go through the engine....which I do NOT think happened. Matratrix stated that if these were left out, I would be visibly leaking out the engine.

18. I am using straight 50 Mobile One oil. I usually like Royal Purple but the Mobile One was on sale for half price.

19. I have been testing with both my electronic engine monitor from Dynon AND a mechanical sensor and gauge.

Okay, that is what I can think of for now. Please, what insight might y'all have. This does not seem to be an issue limited to a rotary but it is a problem with my rotary so I may cross post. Forgive me if you must drudge your way on other sites.

Is there a way to pressure test the oil system? My thought is that if I tried to pressure test it that the oil would simply move around the bearings and such as designed and thus not "pump-up". If I could, perhaps the pumping up would show an internal leak as about the only thing I can think of is that an internal passage is cracked allowing oil to leak out back into the pan and not allowing proper pressure to develop. But, like I said the iron is new (well, a few years old now but purchased new then). I know factory parts can fail as I had the thin water channel passage break in the first hour with a new center plate when I bought the other parts. Mazdatrix replaced it.

I am at a complete loss. I have started the ancillary tear down in preparation to remove the engine from the plane for a better look, but since I am not certain what else to look for, I feel like I am spinning my wheels. I believe I have been methodical but if not, or I am missing things, please speak up.

I have been grounded for the last few months at a nearby airport where I am having to drop an extra $250.00 am month for hangar space. I lost the engine over the airport due to an unrelated fuel blockage in the fuel rail but since the pressure was notably down, I want to address it before I try to fly home...if that ever friken happens....sigh. I would sure like to be throwing that money at a nicer plane and not this circle I feel I am in.

I have spoken with Matratrix at length and they are at a loss.

Thanks everyone.

All the best,

Chris Barber
Houston, GSOT
Velocity SE/FG
Rotary 13b
Ellington Feild EFD and Pearland Municiple LVJ