ASH8

Well my oil coolers are starting to heat after 60 seconds or so from warm up.
About the same time after the first LED goes off 40C.

Where do you get 90C from?,,, RX-7 are also 65C.

I have had it confirmed from my dealers tech that the new EMOP pumps do not actually PUMP on their own, there are just a "Gate" facilitator.
ie, Solenoid Plunger opens lets oil through Via Engines Oil Pump.

"IF" the EMOP's were a "True Pump" there would not be the need to have a Sensor Switch on EMOP to monitor the entire Engine's Oil Pressure would there?
The Engine Oil pressure Sensor/Switch would still be located under the oil filter neck/area like on Series 1 RX-8's? if the EMOP were an actual pump.
There are No other locations on S2s where Engine Oil Pressure is monitored, except on one EMOP.

If it is an "Oil Flow" issue then how come Mazda have stuck to this same design and parts on NA's since 1985.
Two Stationary gear bearings on a 4 port Renny are close to 40 years old...from the Mazda R100 10A.
https://www.rx8club.com/showpost.php...&postcount=120

GeorgeH

iTrader: (2)

Frankly, I’m surprised by some of the comments in this thread. Particularly those that state that it’s a pressure problem, not a viscosity problem.

In Shigley and Mitchell’s Mechanical Engineering Design (a reference/bible for Mechanical Engineering) they state that hydrodynamic lubrication does not depend on the lubricant being introduced under pressure, although it is critical that an adequate supply is present.

That is why the oil is pressurized – the pressurization is a by-product of the need to flow oil through the system and remove heat. But wear is prevented by the presence of a film of oil between the journal and the bearing, and the thickness of that film is dependent on viscosity, not pressure. If you are getting metal to metal contact it is because the oil is not presenting a thick enough film, which means a thicker oil is called for.

Of course, if there is a cold-start issue where for some reason the bearing is nearly dry for longer than a moment or two, then that is a different problem. But I am reluctant to believe that is true.

Yes, this is armchair engineering, and I’d be happy if an experienced lubrication engineer chimed in and explained why basic hydrodynamic theory doesn’t apply to the bearing wear problem on the RX-8. But until that happens, I’m inclined to believe that the bearing wear problem is a viscosity problem. Of all the various theories & solutions I’ve seen posted here relative to engine wear issues, this is the only one that seems like a slam-dunk to me.

Now, what effect the higher viscosity would have on the seal wear is another question.

9krpmrx8

iTrader: (46)

Good input GeorgeH.

ASH8

Here you go...this is the Stationary Gear part number from a 1973 Mazda RX-3 Parts book....

0820-10-502B (2) same ones used in a 4 port RENNY...



AND THE SAME BEARINGS SHOWN IN A SERIES 1 RX-8 Parts File...

ayrton012

These are the minimal value. But a 20 weight could be 9,3 at 100C, and a 50w could be 16,3 at 100C. What do you call a big difference? At 40C the 20w-50 is 150 cst, and a 5w-20 is about 50 cst. So 7cst or 100 cst is a big difference?

ayrton012

https://www.rx8club.com/showthread.p...ler+thermostat

ayrton012

I would like to stand at the oil flow, and maybe the e-shaft pellet. I have oil temp and oil pressure gauge for four weeks, and yesterday I made a test.

Before the results of my test here are some sentences for repetition:

If you warm up an oil from a lower temp to a higher temp, the thickness of the oil is decreasing continuously. If you do it in an engine at a fixed rpm, the oil pressure has to decrease also continuously, as the temperature of the oil is raising.

So my results in the S1 Renesis:

I use Mobil1 0w-30, the outside temperature was 71 F.
I started the cold engine. The oil pressure went up with the very cold and thick oil to 60 PSI, immediately after startup.
After 2-3 minutes on idle, the oil temp still did not reach the 122F. At this point I started with the car, and FIXED THE RPM AT 2000 in fourth gear (no really matter which gear), and looked at the gauges what will happen as the oil is warming.

After some minutes when the oil temperature was closing to the 122F mark, the oil pressure went down to 31,9 PSI (!!!) with the very, very thick cold oil.
It is more strange if you see, what happenned when the oil temp was closing to 140 F. The pressure was continuously raising to the max 58 PSI at 140F.
All this happened on a fixed 2000 rpm. Remember, that in normal case the pressure is decreasing with warming.

After that, there did not happened any more strange thing, the pressure went down as the oil temp raised. But you have to know that even at 160-165F is still 44 PSI pressure (2000 rpm), with the 30 weight oil.

So I have to say, there is something in the Renesis, which decrease (very much)the oil flow under 60C. Is it a dangerous pressure level? Maybe, if you see how thick is the oil in that low temp. This pressure control part has to be the e-shaft pellet. (I don't have any other idea.)

Of course, there is a little chance, that my oil pressure gauge sensor is faulty, so maybe we need more datas from others, before conclusions.

ASH8

Got it, It is more than likely the Oil Cooler Thermostat works in the same way as the Eccentric Shaft Pellet, as in it restricts the flow rather that a complete on/off situation.

Otherwise my oil coolers would never get warm at 40C (Coolant temp) like they do now, there has to be oil flowing through the cooler otherwise there would be no heat felt.

I guess they work almost parallel with the coolant thermostat which has an opening temperature between 80-84 C and fully open at 95 C.

GeorgeH

iTrader: (2)

I see no reason to believe that 32 psi is a dangerously low pressure. As I stated earlier, it's the viscosity of the oil that determines how well the bearings are protected, not the pressure, as long as a continuos supply of oil is present at the bearing, and 32 psi should be plenty to ensure that.

I do agree the dip is somewhat curious, however. But my Miata (the old ones that came with functioning pressure gauges from the factory) would always idle in the 30 psi range (or lower) when hot. Yes, it's a different motor design, but it does illustrate that 30 psi is reasonable to keep the bearings well supplied with oil.

ayrton012

OK when your engine is hot.

But the danger is that this (RX-8) pressure was measured at very low temps, when the oils are very thick. The rpm was higher than idle (2000). And this means very slow flow, after startup under 140F. Lubrication is the flow, the pressure does not mean it in itself.

..and the oil pressure changing between 104F and 140 F is more than interesting. What is the explanation? Only the e-shaft pellet? If the oil cooler's thermostats would play at such a low temps, there would not be higher pressure at 140F then at 122F, and later (above 140F) would not be continuous the pressure decreasing as the temp is raising.

9krpmrx8

iTrader: (46)

Weird, my oil pressures are way off from yours. Immediately when I start my car cold my pressures are at 30-40PSI at 1500RPM idle. Once things warm up fully at idle my pressures are essentially the same. and from 3,000RPM all the way to red line my pressures stay between 75-85PSI.

9krpmrx8

iTrader: (46)

Okay here is some data I forgot I posted elsewhere.


Also, I did a max run up to red line and I got these numbers which are pretty in line with what I recorded before.

RPM: 8335
Water Temp: 195 degrees F
Intake Temp: 104 degrees F
Oil pressure: 83PSI

GeorgeH

iTrader: (2)

Not quite correct. Flow does not equate to lubrication. All that is important to ensure lubrication is an adequate quantity of oil in the journal, which is pretty much assured at 32 psi. Flow rate does equate to heat transfer, which is unimportant when the engine is warming up. Or rather, it is important, and you want to reduce heat transfer to warm the engine faster.

I still don't see a problem with that pressure under those conditions. At least, without additional hard data and/or knowledge, I don't see a reason for alarm.

ASH8

That's because the Miata uses the same By Pass Regulator Piston and Spring as a S1 RX-8, 0221-14-115 and 0221-14-116, used in about 70% of all Mazda made including rotaries, and or basically their banger engines above 1500cc...below this the only change was the spring 0324-14-116B same piston/plunger though.

Flashwing

This is completely wrong.

If pressure was what lubricated and not flow we would all be running around with 80 weight oil in our cars.

Bearings stay separated from other metal parts because of flow.

GeorgeH

iTrader: (2)

Can you provide a reference for this? Everything I have read has indicates that the volumetric flow rate isn't particularly important, at least in terms of establishing a proper film thickness.

Yes, flow rate plays into other concerns, like heat transfer, as well as keeping the oli cool enough that it doesn't degrade, and therefore is crucial in the overall longevity of the engine, but the statement that cold oil at 32 psi is dangerously low because the resultant flow rate won't provide adequate lubrication is, as far as I can tell, false. Do you agree with me on that or not?

[edit] and, I'm not saying it is pressure that provides lubrication - it's clearly not. It is the presence of the oil that provides lubrication - flow just ensures that a fresh supply is always present.

9krpmrx8

iTrader: (46)

Interesting. Love this forum.

GeorgeH

iTrader: (2)

Actually, I think Flashwing and I are stating the same thing, but I’m just splitting a hair to make a point.

Comparing flow rate to pressure, flow rate is what is truly important, since it determines how much heat the oil will pull out of the engine, and how much heat the oil coolers pull out of the oil. Mess up the flow rate and you have a system that either runs too hot or too cold.

Pressure is a by-product of flow rate, viscosity, the physical size of the oil passages, and of course the details of the oil pump. The reason we watch oil pressure as opposed to flow is that pressure is easier to monitor. And, as we all know, if you are at the track and the car is fully up to temp, and the pressure drops suddenly, you have a problem. Maybe something broke, maybe you have a leak, or maybe the oil overheated. Whatever, the drop in pressure means the oil flow or viscosity has decreased from the norm, and you better stop the car and figure out what is wrong before something really bad happens.

But, the hair I’m splitting is that it is oil viscosity (and condition) that ultimately (or at least primarily) determines how well the bearings are protected. Assuming there is enough flow to keep the oil within a proper temperature range, it’s the oil that matters. And, when the engine is cold, a low flow rate isn’t going to cause a problem, in fact it may be beneficial as it will get the oil up to temp faster. Just as long as the flow increases when the engine is up to temp there shouldn’t be a problem.

olddragger

iTrader: (3)

isnt that what the op noticed? it wasnt that number itself, it was the fact that the pressure (number) changed in a spot where it was not anticipated?
remember the volumne of the oil being pumped in our engines is a fixed amount --irreguardless of the viscosity of the oil in the pan. Now the free flow of the oil can be different.

What we should really be discussing is the film strengh and particle suspension properties?
But like what was said --it is easier to monitor the pressure--so it is easier to talk about it also?
OD

9krpmrx8

iTrader: (46)

Man, OD, we are in too many threads. We should all find a spot to discuss everything revolving around lubrication in the Renesis.

olddragger

iTrader: (3)

you know I just relaized that myself Lol!!
OD

GeorgeH

iTrader: (2)

True. But the pellet is doing something to drop pressure, as I understand it. Perhaps part of the flow is being redirected? Or else, the pressure is being dropped due to flow resistance but the net flow to the bearing is unchanged. Either way, it doesn't seem to me a cause for alarm (yet).

Agreed about the film strength comment. That is my point all along. As long as oil is being delivered to the bearing - even at a reduced pressure - during warm up, it seems to me there will be sufficient film strength.

ayrton012

Your datas don't tell too much without oil temps.

Otherwise not the actual pressure is the question. The question is that why there is a big pressure drop, and after that a big pressure increase at a fixed rpm (between 104-140 F), while the oil is warming continuously?

ayrton012

OK, let us see. I stop the warm engine. It (the e-shaft) cools down to below 140F, so the pellet opens the bypass passages of the e-shaft, so the oil drains out from the e-shaft. Is it true until this point?

I start the engine at this point. The pressure has to build up inside the e-shaft, and inside the bearings. But it needs more time as usually, because the bypass passages are opened, and these are bigger diameter channels, than the intake hole of the bearings.

@!!narotordo

I dont go as far as ASH does but I do flush good. I dont see why not. After time and as stated in this thread oil will not hold its temp.