lzamboni

iTrader: (8)

Hi everyone, I have a question regarding the oil pressure in my FD.
The shop finally finished installing the Single turbo setup GT35R, etc. The engine had a half bridge port made and the typical oil modifications.
The thing is, the car is having around 15 PSI of oil pressure at idle when warm and around 30 PSI at 3000 RPM and not more than 55PSI at 6000 RPM.
Now , the car has an aftermarket Oil Cooler setup ( the big dual cooler setup that one of the big vendors sells here ( I cant remember the name at this moment ) and the engine builder ( a very reputable rotary shop ) says that they checked the pressure before the coolers and it was ok. But for some reason it is low at the point of the oil pressure sender even when I connected a new Auto Meter mechanical gauge. By the way, the pressure sender that is in the car is brand new.
What do you think could be wrong and causing that low pressure in the system?
Also, the point where the oil pressure sending unit is, should get oil pressure well before the oil coolers get the oil right? So checking the pressure there should be pretty much like checking before the coolers? Or am I wrong and it goes to the coolers and then to that area?
Thank you for any insights into the problem...
Leo

bumpstart

if you have twin serial oil coolers then the pressure drop through them may be excessive
,, there is a chance that the pressure pre the coolers is 156 + psi and lifting the front oil control reg
( which is there to protect the oil coolers from the overpressure )

as such,, pressure post the oil coolers is poor

also,, if the PD is excessive then there is a chance the front cover O ring has let go ,, thus reducing all the system pressure

disconnect the twin system and dummy up a standard oil cooler and retest system pressure

check the oil isnt contaminated with petrol ,, and is the correct grade for your ambients

KD-93R1

First off I would have to say 15psi at idle is the lowest I would keep it running. If it went below 15psi I would shut it off until I knew exactly what the problem was. Thats to low. Was the porting/engine reassembly done earlier or at same time as single turbo install? Or was the oil pressure higher before you had any work done? I was wondering if rotor/stationary gear bearings are the problem? Need to know whats up w/that or it could cost ya lots more $ ya know.

That AUTOMETER mechanical oil psi guage connected at factory sending unit location is more than likely correct. As for that location, sending unit wise, I feel it
is safe to say that the engineers at Mazda put that in the right place.

lzamboni

iTrader: (8)

Hi, thanks for the replies. I am sorry I was not more specific on the details. The engine was built at the same time with the single turbo setup, so the engine has around 400 miles of running. I am still breaking in the engine.
So basically everything is new. As for the oil pressure before they took the engine down, I think it was kinda the same as now, but as part of he porting job, they did the oil modifications that are supposed to raise the pressure quite a bit.
As for the position of the Oil Pressure sending unit, yes that's what I thought that it was placed before the oil coolers in the system.
I have heard about the front cover O ring going and lowering the pressure in the system.
Now if I do a dummy connection to bypass the oil coolers and test again, if the O ring went, the pressure will stay low anyway even with the oil coolers disconnected right?
As for the oil being contaminated with petrol, I dont think so but will check again. It is 10W30 and the temperature here at this time didnt go over 70 Farenheit so it should be the correct one, even thought I am tempted to change it to something like 20W50 but I dont know if I should wait until I finish breaking in the engine.
Thank you very much guys.
Leo

Turblown

iTrader: (12)

Sounds like the o-ring in the front cover popped out. I've never seen any type of pressure drop from doing bigger oil coolers etc. Doesn't mean its not possible, find out exactly what the oil pressure is before the coolers. I am guessing its also low...

finger lock

iTrader: (6)

Most of the dual oil cooler kits run a thermostat by-pass so the oil does not flow to the coolers until 180F. For a point of reference, my streetported 13B-REW with a single GT 35R turbo and dual Mazdatrix (Mocal) 19 row oil coolers (with themostat) runs about 45 psi at idle when the temps are 180F+, and at 7500 RPM it runs around 115 psi...

This certainly seems like something mechanical...

good luck,

Guy

lzamboni

iTrader: (8)

Ok, as I thought the possible reasons for this low pressure as you guys pointed out are not good at all.
I will try to take the readings before the oil coolers but I doubt they will be any better.
Now, how much work is it to replace the O ring on the front cover?
And if it is not the O Ring, what would be the next possible thing? The oil pump?
Thanks.

lzamboni

iTrader: (8)

By the way, I just check the manual and it seems that the oil does actually go first to the coolers before going to the filter and the Oil Pressure Sending Unit, so in that case I have been taking the readings after the coolers and it makes the reading without the coolers a little more important.
Also another question, the builder told me that even though the pressure is low, at idle is enough if you have as low as 10 PSI and then after that a minimum of 10 PSI per 1000 RPM should be ok to run the car normally. Not the ideal but good enough. IS IT TRUE?? I know that for a normal 4 cycle engine, that applies and specially if the engine is stock. But for a Rotary and a bridge ported one??
Thanks again for your input guys...
Leo

thewird

iTrader: (8)

FD should have over 100 psi by redline.

thewird

lzamboni

iTrader: (8)

Ok, I checked the oil and it actually smelled a lot like gas and seemed to have over the full line of the dipstick, what would suggest it was getting contaminated with fuel.
So I changed it for fresh 20W50 just to make sure the oil weight wasn't having any impact on the pressure ( I know that oil weight could account for no more than 5 PSI but just wanted to make sure )
Anyway, the pressure went up just a little bit. It is at 25 PSI in Idle ( 1500 RPM ) and from then around 33 PSI at 3000 RPM, 45 PSI at 4000 RPM and 55PSI at 5000 RPM.
So I am still in the same place with this. I haven't tested with the oil coolers out of the loop but since the oil cooler thermostat just opens at around 180degrees, if I test when the engine is cold then it should be the same as no oil coolers as they are being bypassed by the thermostat right?
When the engine is very cold ( first 3 minutes or so ) the pressure is at the level that it should be when the engine is warm.
If anyone has any other possible reason for this besides a faulty internal, please chime in.
Thanks...
Leo

thewird

iTrader: (8)

I know someone with an aftermarket oil pressure gauge on the oil filter pedestal and it reads 2.1-2.2 bar at idle (980 RPM). You should have close to 100 PSi by 5,000 RPM on a healthy system. You have half that. Definitely something wrong whether its internal or clogged oil coolers.

thewird

lzamboni

iTrader: (8)

Hi Thewird, thanks for the comments. Unfortunately my car doesnt seem to be the normal case
Now a question, could this be a problem with the Thermostat of the Oil coolers?
Yesterday I got to drive the car before it was completely warm. I had it idling for around 4 minutes before I started moving it slow and the Water temperature was around 100 degrees F so I guess the oil was hotter than the water at that point already. Anyway, the car had a pretty decent oil pressure at that point, something I tohught was only when the oil was cold right after starting the engine.
Could it be that the Thermostat is not opening and the oil doesnt go thru the oil coolers and is just heating up too much?
I touched the oil coolers after driving the car and they were very hot but could simply be from heat transfer and not from the oil running thru them right?
If that was the case, the could explain the low oil pressure.
Let me know what you guys think of that possibility please.
Thanks...
Leo