This is interesting. At operating temperature I noticed my idle oil pressure is below the norm. I was a tad low (1qt) and it has been 5600miles since my last oil change on a good synthetic oil.

Normally at idle (aprox 1Krpm) I would be in the 175-180kpa range.
At load 3000 rpm I'd be in the 580-590kpa range. All normal values for the updated banjo bolt.

I did an oil change today. Currently I have almost 77K miles on the odo.

Before the change:

At idle I was in the 150kpa range. I noticed earlier in the week coming home from work parking in my driveway. I have my warning indicator set to 145kpa and it dipped into the warning when I parked for a brief second since the rpm drops below idle as it ramps down quickly (MAP sensor issue in the cold). This is when I noticed my idle pressure was a bit lower than normal. I figured I was just low on oil and was due for a change.

At load (3000rpm) I was at the 570kpa range when normally at the 580-590kpa range.


After the change:

At idle it's still at the 150kpa range.
At load (3000rpm) it's back the 580-590kpa range. So everything is normal at load throughout the rpm range.

Any thoughts on the cause? My worst fear is the banjo bolt install that was done about a year ago. I've had some bad luck with the shop which is why I don't go there anymore. I doubt this could be oil pump related since the load values are ok but I wouldn

 

Your oil pressure is probably low because your oil pump chain is wrapped around the clock in your avatar.

 

It could be your oil pump. I have seen pumps in other engines able to give adequate pressure under load but fail to meet the min spec at idle. It could certainly be related to the banjo bolts.. if the oil jets weren't functioning correctly, one or more of your bearings could now be bleeding pressure if the clearances were fuxored.

 

Oh you mean that wasn't supposed to be removed?

 

[QUOTE=vtec9,Feb 16 2007, 04:48 PM] It could be your oil pump.

 

According to my service manual is the idle oil pressure 250 kPa.
@ 3000 rpm it should be 590 kPa.
The oil jet bolts have their own valve that opens at 200kPa.
Note that I dont know if the service manual talks about the updated oil jet bolts.

If your idle pressures are at 175-180 range... I donno if that's good.
Oil pump is primary suspect.

What oil are you using?

 

Pre banjo bolt install my idle pressure was 250kpa.

I bought the gauges from a friend with an 03 (updated oil jets). He gave me a list of his normal pressure values. His idle was always around 180kpa and mine was 250kpa. I thought it was odd but didn't worry too much since I was right on spec in the manual.

After the banjo bolt install my idle pressure dropped to 180-175kpa. This was about a year ago now which made sense since i know had the same banjo bolts.

Right now I'm using the German Castrol 0W30.

 

German Castrol is (as you probably know) a "thick" 30 weight.
12.something cSt at 100C as to 10cSt for "normal" 30 weights.

Its good to know that the "updated" oil pressure is 180 kPa at idle.
(but without gauges... as long as it starts I'm happy )
I hope that means the oil jets open sooner too, otherwise there is no oil spray at idle.

A constant 16% drop is something I would be concerned about.
(but without gauges... tic-tac... timebomb waiting to happen?)
During rev dips (MAP related) its IMO normal to see low oil pressure.

Let us know what you find in your "old" pump.

 

The GC is a great oil and easily accessible in Canada. It suits this car well from what I have read.

The drop is ONLY at idle. It's back to normal across the rev range after the oil change.

I think the old oil + 1qt low could have been the culprit in that case.

I will monitor it closely. We expect to see some warmer temps in the coming weeks and I may actually replace my MAP sensor as well (for other reasons).

 

Well it's been 2 weeks and nothing has changed.

Considering my pressure is fine under load I don't think I should be too concerned.

I'll just keep an eye on it for now.