RX-8_Ed

iTrader: (1)

I am using Royal purple 10w-30 and my oil pressure goes as low as 8psi when im idling after the car warms up. Is there anything I can do to fix it? Cause honestly I'm not sure what to do. And I did try searching for it, in the forum, but couldn't find anything on it that helped. Thanks.

dannobre

iTrader: (3)

What is it at 3K RPM's? (It should be about 50 PSI there)

This is part of the reason they don't put oil pressure gauges in cars anymore

FastFreddy61

Try a different gauge , just to verify the one your using is accurate.

9krpmrx8

iTrader: (46)

Where are you getting your readings from? Type of gauge, sensor location, etc.

zoom44

what is it cold at idle? does it change dramatically once the engine is warm or is it the same warm and "cold"

RX-8_Ed

iTrader: (1)

I have prosport gauges with the oil filter adapter plate. At idles when its cold its about 30psi and starts dropping as the car warms up.

I think the reading at 3k is around 50psi if I remeber correctly. I'll double check this afternoon on my way home from work.

9krpmrx8

iTrader: (46)

I would get a real oil pressure tester and check it VIA the factory oil pressure sending unit mount location. You may have to go to the dealer for this.

FastFreddy61

Iv'e seen copious amounts of air in oil pressure lines, enough to give false readings.

9krpmrx8

iTrader: (46)

I don't see how that can be the problem here. It is an electrical oil pressure gauge.

FastFreddy61

I didnt know that, I always use mechanical gauges ,maybe an electrical fault.

9krpmrx8

iTrader: (46)

Yeah it could be a faulty sender.

RX-8_Ed

iTrader: (1)

Ill get a new sender and give it a try.. Thanks

9krpmrx8

iTrader: (46)

I wouldn't drive it until you know what is up. You could do serious damage.

zoom44

hmm get the mechanical readings to rule out the sender. doing some i found it could possibly be the oil pressure relief valve which would require changing the pump to fix.

dannobre

iTrader: (3)

Why would you have to replace the pump? They aren't even on the same end of the engine ..the main relief valve in in the rear iron..and the secondary is in the front

If the pressure is below 50 psi at 3K then it is low..or the gauge is reading low

You need to find out which it is

RX-8_Ed

iTrader: (1)

Actually while driving at 3k rpms it read 55psi. Id say as the oil temp reaches about 160, thats when the oil pressure starts to drop to around 8-10psi only when idling. so if the gauge is reading accurate and the pressure is normal while driving, what's the problem?


Or should i just take it to mazda and have them take a look, but the one here will probably tell me its because of the gauges. They are against anything aftermarket including mazdaspeed....

Jedi54

iTrader: (7)

don't take it to mazda
I'm leaning towards a bad sender.

9krpmrx8

iTrader: (46)

Yeah the dealer might BS about the gauge and oil filter adapter plate. Probably a bad sender, is your factory on/off oil pressure gauge doing anything abnormal?

zoom44

sorry my bad about the relier valve- i thought there was one on/with thepump. anyway same still holds if you've got 55 when its hot and running and it goes to 8 when cold it could be a relief valve. checking the pressure with a mechanical could help diagnose. replacing the sender with a known good sender will help diagnose too.

dannobre

iTrader: (3)

It's supposed to be 50+ PSI at 3K...idle pressure isn't really that relevant unless it's zero

if you have a lot of bearing wear or the oil pump is crapping out it could cause low RPM oil pressure

It will vary a lot at idle depending on the RPM and the oil type and temperature

FastFreddy61

^ Huh?, isnt that relevant at idle? Ask any reputable engine builder and they will respond with a much different answer.

zoom44

its not as important at idle on aging engines. we havent even asked how many miles he has on this engine.

dannobre

iTrader: (3)

I would bet there is a grounding issue with the sensor that is causing it to read a bit lower than actual.....the oil pumps on these engines are very robust...so I wouldn't expect a pump failure...and the bearings the same...not many failures....

So check the gauge