Oil Pres. Control Valve spring?!?
 

I am still trouble shooting my low oil pressure 91 TII. (10psi at idle - 48 @ 3000 RPM - 64 @ 4300 RPM using a mech. oil press. tester). I just got done pulling the oil pan. I was hoping to find a clogged strainer. However, it was clean. Then I pulled out the oil pressure control valve. The thing in the front cover.

Could not get the plunger out but I did measure the spring. It is a hair over 2.75 ". It is supposed to be 2.87" +/- O. And there were two little washers in the bottom of the nut that screws into the front cover. This is an Engine from atkins rotary. Is that something they do?

How does this valve work? Can somebody educate me?

Also the oil pressure is strange when it is warming upt. It is not solid pressure. It fluctuates 5 psi roughly. Just kinda bounces. I need help. This low pressure is starting to depress me

James

This valve is quite simple, really. If the oil pressure coming out of the oil pump gets too high, it bleeds off oil to the pan, reducing the system pressure. The bleed off is determined by the spring length. A shorter spring needs less pressure. Adding washers to the bolt effectively makes the spring even shorter. Would this be enough to cause your problem? I doubt it, stock value is 156 psi (the spring cut in half would still hold 78 psi).

So what could cause this? The eccentric shaft bypass valve comes to mind (It is directly behind the eccentric shaft bolt). I have read that the failure of these valves is a common problem. This valve works by bypassing some of the oil to the rotors when the engine is cold (to accelerate warmup for, you guessed it, emissions reasons! :rolleyes: ). When it fails, it never closes the bypass! Heat the valve up in oil, at 140 degrees F the little gizmo sticking out of the valve should be .24 inches. If you are not worried about emissions, K2RD has a bypass procedure on his web site. Also, Mazdatrix sells replacements or bypass valve thingys to fix.

The last item that could cause this (besides bad oil control seals) is the oil pressure regulator valve. It should start to relieve at 71 psi (sometimes as high as 78) to the oil pan. If it was defective, that is not closing all the way, it may be causing the problem.

The most likely cause imho is the eccentric shaft bypass valve, since these are known to be a weak link. Mine is bypassed, my oil pressure is normal. Good luck!

Irv, Keith's dad :cool:

Atkins Rotary always disables the e-shaft bypass valve on their rebuilds.

The spring measurements you are referring to are important. If the spring is too short it will allow the plunger to open at a reduced pressure. I do not know what the pressure could drop to with a defective valve. I do know the the spring's length is given as 2. 87" and there is no tolerance here. It is however as Irv stated a high pressure relief, designed to open at 156lbs. The other relief valve that is screwed onto the rear end housing opens at 71 psi so this is more likely to be causing your problem if it is valve related.

If you end up taking the front cover off, there are a couple of important things to know. When you reassemble the front cover, make sure you do not use a gasket. Use Hylomar instead. If you look on the driver's side of the front end housing gasket area, you will see a hole, and the front cover has a mating hole. This is the oil supply passage for the OMP. You need to get a short piece of steel brake line tubing and make a pipe that will be a light press fit into the end housing oil gallery. This should stick out about 1/8 to 3/16 inch when it is pressed in. This will keep the gasket sealer you use from plugging this hole up. Also make very sure your thrust bearings are still on the spacer and have not slipped off. This can be checked by measuring the distance from the e-shaft to the hub bore (where the bolt head/copper washer contacts the hub). The manual gives the proper measurement.

You might also be able to see the o ring by using a good light and mirror while the front cover is still on the engine. If you can, you could determing if it is seated properly or has blown out.

Be sure to check the main oil pressure relief valve before you put the oil pan back on.

Good luck.

Mr COPANDENGER........I chuncked the front cover gasket to the side on a car and used the hylomar in lieu of the gasket, and when I got thru and started the engine, the site was declared a disaster area by the federal government. Humor, please. The hylomar did not work for me. It never hardens. Next try I used regular ole GE RTV which sets up and had no problem. Totally agree with the non-use of the cover gasket, but the hylomar proved a problem for me. Do you use it on a regular basis for this front cover? No problems with leakage? If so, it must be something I did wrong. Just curious. And Wankel7, I have experienced this blow out on the front cover (caused by using the wrong front cover gasket{see mazdatrix faq}) and it results in squat oil pressure at idle and under 40psi at 3000rpm, so there is a chance that therein lies the problem. Only problem with that theory is that it was rebuilt by Atkins and the chances are slim that they would screw this up(the front cover gasket). Sorry I don't have any new ideas on your problem. The use of hylomar on the front cover caught my eye.

Hylomar
 

Hailers;

I used Hylomar exclusively on my rebuild this last April. It does not leak or weep oil anywhere.

Hylomar was developed in the early 70's by Rolls Royce for use in their jet engines. I have been using it since the early 80's on everything from turbo prop aircraft to outboard motors. The only place I never use it is on the head gasket(s) or exhaust manifolds. I have never had a failure. When this stuff first came onto the market it was bad ass expensive. I seem to remember my first tube costing about 40 bucks. Back then you could only get it through aircraft parts supply places.

I agree it is very unlikely that Atkins screwed up.

Copandenger.......after I wrote the above post, I thought about your first answer and how you talked about the small hole on the left hand side of the cover and how you treat that. I did not do that when I used hylomar the first time and that was where the leak was. I now just use rtv on the cover and use it sparingly around the eight inch hole where the pressure is. I smear a little vaseline on the housing mating surface so it will come apart at a later date with the rtv on the cover, not the housing. Thanks for the answer.

Thanks
 

Thanks for your responses guys. I am going to call Atkins and ask them about that spring. Also I will remove that relief that is screwed into the rear housing. How do I inspect that thing? The only mention of it is to replace it when it isn't working.

I also will take a mirror and look up the front cover for that seal.

James