I had a thread a week or so ago stating my oil pressure problems. Basically the symptoms are, if left idle, the oil pressure will bleed down to almost 0. At 2k rpm I barely see 30psi, at 4k I get ~50 psi, and it will not go over ~55psi after that, all the way until redline. I was suspecting the front cover O-ring, and that was the feedback I had recieved here as well, as well as from the shop that had built the engine ( ~7k on the rebuild/SP ). Anywho.. yesterday I spent all day changing that O-ring. If youve ever done it while the engine is still in the car, you know its a major PITA. Well I got her all buttoned back up, added oil, coolant, etc. Sat in it, car fired up and seemed to be running great. Just as Im about to give myself a big pat on the back, I go check the oil pressure... about 0. The symptoms are still the same. I changed the front 0-ring, and the oil pressure relief valve in the front cover appeared to be fine also. What else could be causing my problems? Please dont say anything else behind the front cover... I really dont want to do that again...

 

Check the oil pressure connector near the rear rotor housing. Sometimes these get soaked with oil/corrosion or just a bad pressure sender and it will give false readings. The last thing you could do is get a oil pressure checker and hook it up to the oil line. Try squeezing the oil line when it's idling. If it's hard, you are getting pressure.

 

Ive verified my readings with a mechanical gauge, as well as replaced the pressure sender unit with another. When I squeeze the line going from the front cover to the oil cooler, it feels soft. I verified all that before tearing into the front cover, and the symptoms havent changed.

 

And you went to the MAZDATRIX site and looked at their FAQ with pictures of the front cover and what most likely goes wrong? That site has jpg's of the cover and what might go amiss.

 

Yes sir Replaced the 0-ring along with the white teflon ring because mine is the S5 with the larger casting, and used the correct gasket.

 

Well, if everything was done properly, either you have a blocked debris in the oil line bad thermal pellet OR the oil pressure valve is no good (maybe a cracked spring). Although those above are rare it can happen and can't see anything else. The thermal pellet should have been done while you were at it. You can use shims instead of the solid pellet.
It just leaves those above. Yea, sorry to hear. Don't you hate it when that **** happens?

 

Forgot to mention, the engine does have a thermal pellet. From when I had the front cover off, the pressure valve ( youre talking about the spring in the bottom of the front cover, leading to the passage where the 0-ring goes, correct?) appeared to be ok. If there was debris in the oil line, youd think it would still be pressurized as normal ( if not more so?), but as I said, I can squeeze it with my fingers when the engine is running.

 

Yeah, I would be leaning towards a bad E-shaft thermo pellet for the frist check rather than ripping the cover off, since you don't have any symptoms of a bad front cover O ring (oil pressure goes down the higher RPM you go if the O ring is bad).

So a couple of things I would check:

What kind of oil filter are you using?
Is it the stock oil pressure regulator, and if so how many miles on it?
does the oil cooler get warm/hot when the engine is warm/running?

 

If the oil pressure checked out using another gauge and everything is ok, ... ??
If the gauge is bad it will go into default which is all the way up.
You have proper lever oil there don't you?? LOL.

 

Oil, as well as filter has been changed. Mazda OEM filter was on there originally, replaced with a Pure1 ( all out of mazda filters, need to order more). Oil is castrol GTX 10w40.

Icemark , as for the pressure regulator, Im not sure if its the original or not, but I do have a new one sitting right here beside me, guess it couldnt hurt to change it? About the only thing left I can think of. Ill check to see if the cooler gets warm tomorrow, to verify that it is at least getting oil through it.

 

Well you can probably rule out the oil filter then.

Remind me of your set up... non turbo? Turbo ? Modifcations?? recent rebuilds or blown motors?

And what made you think that it was the O ring???

 

Sorry, its a '90 GXL, I actually just purchased it last month. Has a recent rebuild/streetport done by JR rotary in NJ. Thought it was the o-ring because of generally low pressure all around, and not giong over ~55psi, and knowing it had a thermal pellet mod done at time of rebuild.

 

sounds like a stuck oil pressure regulator, but its hard to say without seeing it...did the old motor blow or loose a oil seal?

 

The old motor was blown, lost a few seals. Needed both housing replaced. The pressure regulator isnt that bad to change, infiniately easier than the front cover o-ring, I think Ill just change that out sometime soon. Ive never had one go before, are my sypmtoms typical of a bad regulator? Liek I said, my pressure will bleed of to about 0 at idle, and it wont build more than 55psi total.

 

It sounds more like a bad E-shaft thermo valve, but I did see a oil regulator that got metal jammed into it when the engine blew do the same thing.

 

Well, replaced the oil pressure regulator this morning ( the one on the rear iron, under the oil pan), and no change in pressure. Any other suggestions, Im about out....

 

Mark, when you said this, do you mean the regulator on the rear iron, or the bypass spring in the front cover?

 

A stretched oil pump chain maybe?

 

Dont think so, when I was under the front cover, everything looked good to me. Plus like I said, recent rebuild, by a very reputable shop, so Im sure its new or at least was in spec within 7k miles ago

 

^

 

It has to be some kind of false reading...if it's 0 psi @ idle, and truly 0 psi the car wouldn't run, would it?

 

Its not quite 0, its about 5, maybe 4, but I blip the throttle if I have to drive it, blip to 1500rpms and it will go to ~30psi, and then slowly bleed back down.

 

The only things that would cause pressure problem is:
pressure valve (front cover)
pressure sender (rear iron)
bad o- ring ( changed that)
oil leak (none ?)
clogged oil filter ( checked?)
bad thermo valve in oil cooler (does oil get hot in the cooler ? It may cause high oil pressure now that I think about it)
kink in oil cooler line

If the gauge is bad, it goes into default which is the needle pointing up.
It sounds like a pressure sender causing that but if you changed to another then that rules that out unless you have 2 bad senders. When you hooked up another gauge, did it give a reading at idle?

 

Yep, exaclty. The oil cooler gets warm , seems to be doing its job fine. I can hold the oil cooler line feed line and feel oil going to it from the front cover, but when the rpms drop it idle, it gets very soft ( low pressure...). When I blip the throttle and the pressure comes back up to where its supposed to be, I can feel the line inflate and get rock hard, and feel the oil pulsing through. The only thing I have not changed is the pressure valve in the front cover, so Im going to be doing that. I would have liked to have done it today when I had the oil pan off to change the OPR on the rear iron, but I dont have a new one yet.

 

You should replace the front thermowax with a solid unit. Also you should change both regualtors in the front and rear irons.

Side note also doesn't the stock oil pressure regualtor bypass at 60psi?