olddragger

iTrader: (3)

actually the pump doesnt cause pressure ------what causes pressure is the resistance to the flow of the oil its trying to pump. So maybe a regulator mod can fix this?
Since the oil pump is a moving part that doesnt get supplied with filtered oil i wonder if the clearances within the pump is OK. No magnet in the pan either?
Does blowby affect the pressure if it is not vented well? I know vacuum pumps will reduce oil pressure......

Ash --are those springs assessable and what do you recommend for replacements?
OD

9krpmrx8

iTrader: (46)

I don't think many guys on this board would fess up to poor maintenance.

ASH8

wow...I have made a huge discovery

There IS a difference in the OIL PUMP Relief Valve SPRING which is separate from the Pump itself, but close to it..this spring IS SERIES 1 RX-8 Specific..

OK...
ALL the OIL PUMP Relief Valve Plungers are the same in all FC, FD RX-7's and S1 RX-8...Mazda Part Number 0839-14-115 Plunger (which originates from the 1971 RX-2)...

BUT there are 3 Different SPRINGS that actually "regulates" Plunger Movement or Tension...

0839-14-273A FC RX-7 NA and Turbo (again Spring originates from RX-2)
N3A1-14-273A FD RX-7 ONLY.
N3H1-14-237 FE RX-8 Series 1 ONLY.

So could this N3H1-14-237 SPRING be part of the problem/issue??
Someone would have to either Buy or Compare the 3 springs to feel the differences...

EDIT: Just added a Pic of the parts and location...

MORE to Come on the REAR BY PASS Valve....

ASH8

Rear Iron Housing BY Pass Valves for S1 RX-8 and RX-7's.

Both the FC and FE (S1) use the same Regulator Assembly (see Parts Pic)..



3648-14-250 Regulator Assy....
Inside Unit..
0221-14-115 Plunger
0221-14-116 Spring


The FD RX-7 has a Different Regulator Assembly (see Parts Pic)



N3A1-14-230 Regulator Assy....
Inside Unit...
0221-14-115 Plunger as the RX-8 and FC.
BUT They List NO PART NUMBER for the Spring!!??

I have tried making it up by model code, but won't work, it could be the same
0221-14-116 Spring as the FC and FE RX-8, BUT, I can not be sure, if it was the same spring why did the Assembly Part Number Change?

9krpmrx8

iTrader: (46)

Hmmmmmmmmmmmm.

ASH8

So OD...Confused YET...

I am thinking now ONLY to Change the OIL PUMP RELIEF VALVE SPRING in Series 1 RX-8's as this should in theory increase flows/pressure of ALL Oil Through the Eccentric Shaft to it's REAR and to Rear By Pass Regulator...

BUT, we may need someone to purchase these 3 springs and see which one to use, as I see it the SPRING with the STRONGEST Resistance to compress would be the one to use as it needs more OIL pressure to push plunger down to by pass...

Paul or Mr.E would be the ones to ask...IMO...Where are you PAUL!!

I am thinking this spring...0839-14-273A FC RX-7 NA and Turbo, then you would have the EXACT SAME Parts and Relief Valves as the FC RX-7 to match everything else.

The Oil Pump By Pass Pressure in the S1 RX-8 with N3H1-14-237 Spring is 64-71 PSI, we need to find an FC RX-7 Service Manual to find the PSI Numbers of it's Relief Valve opening Pressure....this should definitely tell us..

BTW: I am pretty sure you can get to this OIL PUMP Valve from the Front of the Timing Cover, it is at the left side just above the sump pan join, it is a Large Nut, I think about 12-15mm...
See parts pic...

Will try and find out more...

REMEMBER I AM NOW SAYING LEAVE THE REAR BY PASS REGULATOR AS IT IS, AND ONLY LOOK AT THE FRONT OIL PUMP PRESSURE REGULATOR SPRING.

ASH8

I can not believe what I have found after ALL this......

ALL these issues have to do with the OIL PUMP RELIEF VALVE OPENING PRESSURE!

Here is why...

I have found on-line the FC RX-7 Oil Pump Relief Valve Opening Pressure from a workshop manual (see pic and RED highlight)....and you would never guess which it is the same as.....

The Series II 09 OIL PUMP!!! of 156 PSI, Not the Meagre 64-71 on the Series ones...

SO there it is, change to the 0839-14-273A Spring and you could possibly have the same oil pump pressure as the new Series II RX-8 and the FC RX-7.

The Rear Regulator Pressure in the FC RX-7 is 71 PSI (see Green) is the same regulator valve (3648-14-250) used in the S1 RX-8, I would now leave this unit where and as it is.

So basically at present you have a WEAK Oil supply with no more pressure than the By Pass Valve in the rear is set at to BY Pass...71 PSI

NO WONDER THE BEARINGS ARE STARVING OF OIL...JUST NOT ENOUGH GETTING THERE!...RG was Correct ...

I was going to do my Mazda Part Number "investigation" on these Oil Pump Relief Valves...but didn't, mainly because in all my years I never sold any and did not think this was the issue, I was concentrating on the Oil Pump itself and the Rear Regulator, when it is the front Oil Pump one!.

ASH8

I thought access to the Oil Pump Valve was through the front of the cover, but is inside the sump behind the Red ring on front alloy cover..see Pic..

From memory I was sure earlier Rotaries had access to this valve from the outside...sorry about the misinformation.

So it appears you have to remove your sump to get to it...like the rear by pass valve.

BTW: You can see next to the red circle (white tape) the Oil Cooler FEED Line directly from the oil pump.

ASH8

Found a diagram on how to remove and replace oil pump regulator valve, this pic is from an RX-7 WS manual.

I have to say, although the Plunger (0839) is that from the RX-2 and 7, and the large Nut is also from the RX-2 and 7 and used in the Series 1 RX-8, we know by part number that the spring is different in the S1 RX-8.

So there is a possibility that the "tube" or "liner" that the piston and spring goes into Could be Shorter in length, in other words the piston travel may be shorter requiring a different or smaller spring or even longer spring? where it goes into the front cover. The Standard FREE Length of the Spring (0839-14-273A) is 73mm.

We really will not be able to tell the difference in these springs unless we can compare all 3...everything else is the same.

BTW: You can see the REAR By Pass Valve in the Rear Housing behind the "Hand's Finger" in sketch.

ayrton012

Yes, the pump will move the same volume, but a bigger part of this oil volume will drain back to the pan at the regulator valve, instead of circulating (flowing) in the engine (bearing).


So less oil flow = the oil spend more time in the engine = higher oil temp (at the bearing).

ayrton012

More than good find! Maybe it is the answer that we are looking for long times.

Maybe the lower pressure in the S1 was for economy reasons. The higher pressure needs more fuel. So the mpg will less with 0,1 miles. Who knows what Mazda was thinking?

But one thing I don't understand.
If we have one regulator valve with 71 PSi, and one control valve with 156 PSI in the same engine, how would we get higher pressure than 71 (70-80PSI)?
Doesn't the lower pressure valve prevents to get higher pressure?

ASH8

I deleted my last message because I was referring to the 09 setup which is slightly different.

Have include a similar oil circuit to the Series 1 RX-8 (this is an FC circuit).
From Pump via Control valve, through to oil coolers, returning to the rear of engine with rear by pass regulator to oil filter, filtered oil into e-shaft, return through top housing oil gallery to MOP. (in pick also to turbo if fitted).

Obviously depending on RPM would determine the amount of oil by passed back into sump from regulators.

The Series II 09 does not have a rear regulator, nor does it have an oil filter at the rear of engine.

PhillipM

Thanks ASH, our engine's still out of the car so if I get time I'll compare the 3 spring rates/length/preloads/installations - only trouble is, the car is competing this weekend, so I'm not promising I'll be able to get them for you.

The next one to work out, is why exactly they used that spring in the series I cars.

PhillipM

Different installation, different heat and pressure levels in the bearings, we've been through this once, the RX8 has cooling issues in hot temperatures due to the engine bay design as it is, what's that doing to the average block temperatures?


It's not as simple as "it's the same bearing!" - I've seen crankshaft failures in cars and plants with engines bolted in from another car, or standard plant engines used worldwide, which never normally have a problem - what was the fault there then?
Different vibrational frequencies causing fatigue that's not normally seen, just simply due to the installation.
I've seen engines seize in development cars and bike for no apparent reason, the same engines used thousands across a range, why did they fail?
After much searching - different body shapes/engine bays causing unpredicted dead spots in the airflow in different points around the engine, there's been many times when the rearmost cylinder(s) have been sat in still air, creating a lovely warming blanket - even though the rest of the engine temperature was spot on, the rear cylinders are running 20*C hotter than the rest....

You've also got the extra engine revs. to consider, as discussed previously, they make a massive difference to bearing wear - see attached graph - especially if your oil is breaking down and the EP solid lubricants are dropping out of suspension.

ayrton012

So if we want to increase the max pressure in the S1, we have to change the spring in all of the two valves (regulator and control), or we have to take out the
rear bypass regulator, and change the spring in the oil pump control valve.

Maybe that would be the best, leaving only one control valve in the oil circle, as in the S2.

olddragger

iTrader: (3)

Now thats a REAL PARTS MAN!!
Ash ,man i bow down to ya. Great work, great work.
Time to break out some old stuff in the storage block and see!
OD

9krpmrx8

iTrader: (46)

Yeah people keep referring back to the same parts but those parts are not being used in the same environment. The Renny makes a lot more power than the other NA rotaries are revs higher. Some of this we have been over a hundred times.

This is great info on the springs though. I can't wait to see where this goes.

ayrton012

My doubt is that in the FC's were regulator valve with 71 PSI, so the max pressure did not depend on the 156 PSI control valve.

If there are two valves in the same line, always the lower opening pressured valve will determine the max. pressure.

That is why we have to do what Mazda did on the s2, leaving only one ( 156 PSI)valve in the system.

ASH8

To reply to both your posts...
I am suggesting you leave the rear by pass regulator alone at this stage.

From my knowledge and going back this is the first time Mazda has removed the rear valve in Series II's, and the S2 is/has a different oil circuit.

ASH8

Would be great to know Phillip...
Look after ALL this there may be NO difference between spring sizes or it's installation.

I would be pissed to see that Mazda made a "printing error" with ALL their Oil Pressure specs??

You can also Upgrade the Oil Pump in Series 1 RX-8 to the FD or FC Turbo one.
The two Pump Rotors are 5mm wider each = higher displacement.

Nubo

Check the caption for the 2nd pic in this series. Appears that there is knowledge of this in the field...

http://www.aaroncake.net/rx-7/projec...ay262005-1.htm

ASH8

Yep good find, this is an FC engine
.

9krpmrx8

iTrader: (46)

Shimming huh. Can that exact thing be done on our cars while the motor is installed?

ASH8

If you can remove the sump pan... then yes..

PhillipM, is investigating these springs so we may have some news soon about spring size.

9krpmrx8

iTrader: (46)

Sweet.