I have searched the site but cant find an answer yet that may be helpful... Appreciate your advice guys.

Recently, my oil presure have been at 18psi instead of the normal 25psi when idyling at 750RPM. The main problem is that during crusing it drops to 10psi when i disengage the gear, or when it is at neutral. Everytime i do this, it will drop to 10psi and then return to the low 18psi at idyling. I also notice that the RPM also drop to 600RPM before going back to 750RPM(idlying) when i disengage the gear.

Appreciate any comments on why I have this problem and low oil pressure reading. btw, I am using the Defi Oil Pressure meter to guage my reading.

Thanks in advance!

Don

 

4 questions:

1. What weight, type (mineral or synthetic), and brand of oil are you using?
2. How warm is the weather when you are seeing this low pressure?
3. What is the coolant temperature when you see the low oil pressure?
4. How long has this oil been in the car?

Dave

 

What is your indicated pressure when the engine is running faster? The Factory Service Manual calls for 50 psi (minimum) at 3000 RPM.
What viscosity or weight of oil are you running and how long has it been since it was changed?
Does the oil have a heavy smell of fuel?
If your stock oil pressure gauge is still hooked up, does the DEFI readings and the OEM gauage readings roughly correspond?

 

I have the same thing going on. I was told it is most likely a problem with the sending unit since the engine only has about 6k miles on it.

 

LOL, Sorry Dave, I repeated a couple of your questions.

 

Well, you were writing same time I was - if I had posted 2 minutes later, I'd have repeated yours.

Dave

 

He has a different pressure readout from stock, so his may not be the sender.

Dave

 

If your still using the stock gauge and sender, it's probably a problem with the connection or sender or a combination of both. Pressure is also influenced by the weight of the oil, engine temp, rpm and occasionally by fuel dilution.

 

Wow, im impressed with such quick replies! Thanks!!

Here are my answers Dave:

1. Im using Shell Mineral Oil 50w-20, call Shell Helix Super. Below is their Website.(http://www.shell.com/home/Framework?...s_ga_1509.html)

2. The weather temp could be anything from 26 to 34 degree celsius(Im in Singapore, tropical city and its hot during the day). The weather doesnt seem to affect it though. What does is the oil temp. When the oil temp is 70 and above, the Oil Pressure starts reading lower as oil temp rise, oil press will reach lowest point of 18psi and stays there. Of course it drops further when the idyling falls below 750 at times when disengaging the gear.

3. Water temp is approx 82, when its at low oil press.

4. I changed my oil and spark plugs recently like 2 weeks ago but there dosent seem to be any difference, it still has low oil pressure. I change my oil about every 2000km since its mineral. My oil filter every 4000km because my R-Magic Filter is not cheap(Got to use this Filter because of my Oil Press/temp sandwich).

About 5 oil change ago, I used Trust Greddy oil and everything was going well. But those oil cost a bomb like US$90 for 5 liters, so i change to Shell mineral oil. No problem, until recently... So i have not associate this problem with the oil I am using.

I am using Defi Water Temp, Oil Temp, Oil Press, Fuel Press, Exhaust Temp to monitor the system. Thats where i get the above readings from.

Thanks!

 

Hi Sgtblue, I have not check for the 50psi at 3000RPM, will take not of it. My Oil press has always been 25psi at 750RPM which i reckon is abit low... But didnt worry abt it till now cos my Defi controller is constantly beeping at 15psi and below, and I think that is way too low.

Nope, i dont think the oil have a heavey fuel smell. I check later to confirm.

Yes, my stock gauge is still hooked up, but I cant tell wat psi it is exactly at with the OEM readings.. any idea?

 

Nothing you replied raises any red flags about your oil, etc. (I assume you meant 20W-50, not 5W-20 or ??W-20).

However, if I recall correctly (IIRC), there is a thermal bypass (causes oil to bypass the rotors so they warm up more quickly) that results in lower oil pressure while the engine is cold. Also, IIRC, there was some mention of these sticking and not closing the bypass after the engine had warmed up.
Normally, the oil pressure is high at first start-up cold, then begins to drop off as the engine warms, then the bypass closes, and pressure goes up again to normal readings (or above normal, but then comes back to normal after more warm-up). Do you see this sequence of events? If not, the bypass may be stuck in bypass mode.

Another thing that could be wrong is that the oil cooler fins could be bent closed or clogged, allowing the oil to get too hot, or, the oil cooler bypass thermostat could be stuck in bypass and the oil is not getting cooled.

Dave

 

I eliminate the thermal bypass pellet in most of my rebuilds. I see it as just another failure point. It can be done with the motor in the car, but you need to be very careful as the e-shaft bolt needs to be taken out.

 

Thanks for the info guys!! I will check the thermal bypass to see if that is the problem