Thank you all for your replies
FYI
kg/cm2 x 0.9804 = bar
kg/cm2 x 14.223 = psi or lb/in2
I found this in someother forum and I think it makes sense in someway
Trong
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(Msg. 1) Posted: Sat Jan 22, 2005 6:40 pm
Post subject: Low oil pressure at idle 93 Trooper
Archived from groups: alt>autos>isuzu (more info?)
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A few days ago I noticed that when at idle my oil pressure needle flutters
just above 0 and the oil light flickers on and off. Once I'm on the gas the
pressure seems fine. This happens more often then not but it is a random
thing. Oil levels are fine. As a mater of fact, I just added oil prior to
noticing this problem.
What should I be looking at. Pressure sensor? Oil pump? Any other ideas?
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(Msg. 3) Posted: Mon Jan 24, 2005 2:35 am
Post subject: Re: Low oil pressure at idle 93 Trooper [in reply to: Login to View]
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I used to own an 85 Isuzu 2.2 turbo diesel C223 engine in a Jackeroo. The engine being an old diesel it suffered from exactly the same problem and after checking with a capillary type gauge I noticed that the oil pressure at idle when cold used to be at 85 P.S.I. (which is a lot higher than any petrol engine that I have owned)and when hot at idle used to drop to as low as 10 P.S.I. sometimes even 5 P.S.I.
Once the engine revs were raised up the oil presssure then went up to about 45-60 when hot. So it was only ever a problem at idle. I have been told that this is a common thing that happens to old diesels and not to worry to much about it.
It is caused by wear in the big end bearings thus increasing the clearances between the con-rod and bearing. Due to the extra clearance the pump has trouble keeping up pressure and the fact that the turbo heats the oil more than normal wouldn't help either. But this only a problem at idle when the engine is under no load anyway.
I used to run a 15W/40 weight oil, but because of my problem tried using a straight 30 weight oil, but this actually made it a bit worse. My next step was going to be, trying a penrite oil 20W/60 which I have no dought would of fixed the problem. But I got rid of the car before I had a chance to find out.
However mine was never that bad that the temp light came on. They are normally set at around 3-5 P.S.I.
If I were you I would check the oil pressure with a capillary type gauge just to rule out a possible elctrical type fault. If your pressure comes reasonably high with this gauge when cold then you can probably rule out a problem with your oil pump and put down the pressure drop to increased clearances inside your engine.
I would also check if the idle speed is set high enough. If it is, it probably wouldn't hurt to bring it up about 150-200 R.P.M. anyway, which should raise your pressure by a bit at idle.
Just as an exercise - When turning off your engine switch it straight back to the ign positon and see how long it takes for you oil light to come back on. When cold it may take as long as 5-10 seconds. When hot it will come back on nearly straight away. On a newer engine even when hot it will still hold its pressure for about 3-5 seconds.
