Rxmfn7

iTrader: (4)

My newest FC ( 90 GXL )seems to have developed a problem with the oil pressure. I have not verified this with another mechanical gauge yet ( I will, havent had time), but assuming the stock gauge is correct, Id like some input on what the problem may be. The engine has ~7k miles on a new rebuild/streetport, done by JRs rotary in NJ. I think that they replace the front oil thermovalve with a pellet in all their rebuilds, but I will call tomorrow to find out for sure. When car is 1st started ( cold ), and a 2krpm idle, the oil pressure reads ~40psi. When warmed up and at idle (650 rpm, a bit low) , it will drop to ~15-20psi, and then if I sit for a minute or 2 ( as at a stoplight) it will drop to about 0. At 2k rpm, it sits just above 30psi, and at 3k I get 40psi, and at 5k or above, I get ~50psi. It doesnt move above 50psi from about there, all the way to redline. Like I said above, I will verify with a mecahnical gauge ASAP, but as it is, Im slightly scared to drive the car. Im thinking front cover o-ring? Any suggestions?

RotaryWeaponSE7EN

iTrader: (6)

Make sure they replaced it and test with a different gauge thats all we can really tell u for now.

dorkman52000

What about replacing with a different sender unit? My car did the same thing until I replaced the sender unit next to the oil filter with a new OEM one. However, I also had the problem that it was never consistent. Sometimes when driving at highway speeds the thing would drop to zero for a couple of minutes then all of a sudden rise back up to where it sat before, around 40-50 psi (that's low, I know). I decided to replace the unit since it wasn't consistent, and it would leak oil from the threads on the unit itself when the car was at idle.

Now my pressure levels are just like new, the car does not leak oil, and it is like a weight has been lifted off my back. I would still check with an extra gauge, but I'm just throwing out a suggestion to check that sender unit as well.

BTW, my measurements now are like 60-70psi highway cruising 5th gear, and around 100-110 startup or extreme acceleration, and about 35-40 at idle.

scathcart

Check with a mechanical gauge. They cost $10 and take 10 mins to install. Until then, we can't know for sure what your oil pressure looks like... we all know you can never trust the stock guage and sending unit.

If you really believe you have zero oil pressure at idle, loosen off your oilf filter while the car is idling... If oil comes shooting out, you can NOT have zero oil pressure.

fstrnyou

i'm having a similar problem. when i first got the motor the pressures were over 100 at startup, 60 at cruise, and 30 at idle.
now, it's 60 at startup, 45 at cruise, and at the correct idle it's at about 15-20psi.

i guess i'll replace the sender to see what happens.

Rxmfn7

iTrader: (4)

*sigh...* Well Ive done a few things and I think Ive narrowed it down the to front o-ring Today I changed oil and filter, with no change it pressure readings. Changed out sender unit with a spare I have, still no change. Hooked up my mechanical gauge, and its about right on with the stock one. 15-20PSI at idle ( drops to almost 0 if it sits for a few minutes), ~40 at 2500 RPM, going to a max of ~55PSI and then staying there till redline. I was on the phone with JR Rotary that did the rebuild, and he did confirm that he does use a pellet in all his rebuilds. He also suspects the O-ring, or possibly the pressure regulator in the front cover. He informed me that I should try and squeeze the oil cooler line going from the front cover to the oil cooler, and It should be extremely hard to squeeze at idle, if it is getting all the pressure it should. I could almost pinch it 1/2way with my thumb and index finger. So I guess Ill be pulling the front cover off soon Only had the car 3 weeks and now I have to do a "major" job , just kind of depresses me. Do I need to drop the oil pan to get the front cover off while in the car?

fstrnyou

maybe not, but you may have to take some of the oil pan bolts out, mainly the ones that go into the front cover. i thought the oil pressure regulator was on the rear iron..... at the bottom, passenger side i think.

dorkman52000

I think you do...I did the same job on my '87 a couple years ago, and I had to take off the pan to take out the front cover (but I was planning on it anyway because I needed to replace the gasket). Also, I didn't have adequate enough tools, so I had to remove the engine mounts and jack up the engine a bit to get at the bolts on the front of the oil pan since they are located pretty much on top of the crossmember. I don't know if anyone else with better tools than I had at the time has to do the same...I ended up using a 10mm (?) wrench and the only way I could get at them was by jacking up the engine.

Anyway, I believe the oil pan has 4-6 or so bolts that go into the base of the front cover, so you have to at least remove those. I may be incorrect and it bolts to the front rotor housing, it's been awhile and I was really pissed that day because it was taking me too long to get the damn thing apart.

Rxmfn7

iTrader: (4)

Yea I understand that the bolts will have to be removed, just didnt know if the whole pan had to come off. Im guessing so, because Ill probably destroy the gasket while taking the front cover off. Im just really not looking forward to doing this.. I just placed my order with mazdatrix though, so Ill get cracking on it as soon as I can. For those that have done this while in the car, how long of a job is it?

locketine

if it's your first major project like mine was, it'll take atleast 12 hours. I'm not great at resourcing parts beforehand though so some of that time was driving to autozone.

ya might want to look for my posts on just this subject. I made a new one just two days ago. I've done everything I could to the front cover and I still have the problem, and now I've been instructed to flush my oil cooler which I'll do this weekend.

Rxmfn7

iTrader: (4)

Its my 1st time taking the cover off while the engine was still in the car, thats all im worried about. Plus this is now my daily driver, and I cant afford too much downtime. And dropping a bearing scares me

dorkman52000

If you're going to do it this weekend, start on Sat morning and expect to still be at it Sun morning. Don't work too fast because you'll forget how things go (I believe the W/P bolts are different lengths, etc.) It took me a few days actually because when I ordered the gaskets and o-ring beforehand, Mazda sent the correct part numbers, but the parts inside the packages were some other dealership's return, and they were wrong. Also, while I was at it, I replaced the W/P and thermostat.

Also, in regards to your earlier question, I don't think you have to remove the pan entirely, just remove the 4 or so bolts that hold it to the front cover. I decided to remove it anyway so I could replace the pan gasket with a new one.

Good luck with it! I think you'll do fine, just be careful and get that o-ring held in place when you're putting the cover back on. Mine decided to be a bitch and move a couple times before I did it successfully.