oil pressure

Submitted: Monday, May 12, 2003 at 15:01
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I own a 1992 ubs jackaroo v6 3.2 I have had the oil pressure tested and the readings were 10 psi at idle and 50 psi at 2000 revs. the oil pressure gauge is on the high side when first started cold then declines to very low after warm up and stays there, can anyone tell me the correct pressure that this engine should run at, maybe at idle and 2000 rpm.

I am about to pull the engine down to check all bearings is this the way to go, thanks for any help on this matter. regards jack
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Reply By: Savvas - Monday, May 12, 2003 at 15:27

Monday, May 12, 2003 at 15:27
I'm not sure what pressure you should have, but what you are describing sounds like excess bearing clearances.

You didn't mention whether the oil test pressures are cold or hot. Also, how many km's has the motor done?

The long term fix would be to have the bearings redone, but as an interim have you tried running an oil like Shell Helix Super for Older Engines? It is a 25W-60 oil that runs a bit thicker, helping keep oil pressure up when warm. However, there is a downside in that it is also thicker when cold and won't circulate as quickly as most other oils at startup.

Valvoline also has a new oil out for older engines, called Maxlife. However I can't find a viscosity rating for it. Ideally if it is a 20W-60, then that one would be the go as it would circulate at startup as most other oils.
AnswerID: 19751

Reply By: crfan - Monday, May 12, 2003 at 16:09

Monday, May 12, 2003 at 16:09
Get the specs for the engine a holden v8 is 7psi at idle 40-60 at 200 rpm
may be ok does it make noise on start up at cold ?
AnswerID: 19757

Reply By: Member - Wherethefugawi - Monday, May 12, 2003 at 16:52

Monday, May 12, 2003 at 16:52
I beleive that one should only measure oil pressure when oil is at operating temp. All veheicle oil pressures are higher when cold.
AnswerID: 19763

Reply By: David N. - Monday, May 12, 2003 at 20:52

Monday, May 12, 2003 at 20:52
Firstly make sure your readings are very accurate. ie: accurate calibrated mechanical gauge.
Just last week I had concerns re oil pressure on my TD42- turned out to be a gauge problem. ( I sorted that out and find I actually have excellent oil pressure.)
Then- low oil pressure at idle often tends to indicate excessive bearing clearance, whereas good idle oil pressure but below specs at revs often indicates a regulator or pressure relief valve problem.
Cheers and good luck
AnswerID: 19798

Reply By: Member - David - Tuesday, May 13, 2003 at 13:30

Tuesday, May 13, 2003 at 13:30
I have 'AutoMeter' battery condition & oil pressure gauges in the 3.2 V6 rodeo..the 'oil' is the electric type- not the capilliary type- and oil preesure HOT is:
Idle. (about 750 rpm) is 25 and at 2000rpm is 70.
The vehicle has done 122000km...and its next oil change is due soon. I do note it is higher with new oil & filter.
I don't guarantee the accuracy of the gauge..as I just take note of dramatic changes (none yet????).
I hope this is of some help to you.
A bad days sailing sure beats a good day at work
AnswerID: 19876

Reply By: Trevor - Friday, May 16, 2003 at 02:33

Friday, May 16, 2003 at 02:33
We have a '97 3.2L Jackaroo with just on 100,000 Km on it.
Our oil pressure when hot is 300Kpa at idle and 580Kpa above 2,800rpm.
Our Isuzu Workshop Manual ('92 on) states that oil pressure should be 350 - 550Kpa (51 - 80psi) at 3,000rpm.
As somebody else said, the best method for checking the pressure is to temporarilly install a pressure gauge in place of the Sender Unit.
You can also check the electrical side of the dash mounted pressure gauge.
Unplug the Sender Unit wire and check the voltage. It should be about 9-12 volts.
The Sender Unit resistance varies, depending on the actual engine oil pressure. Disconnect the wire and measure between the terminal and earth. The body of the Sender wii do.
0kpa - 19ohms
50 - 26.6
200 - 49
400 - 80
600 - 110
These figures are from the manual, but our car was different. They may apply to yours, being a '92.
You can also make a simple test rig. Buy a 200ohm potentiometer (variable resistor) from Dick Smiths. Solder a piece of wire to each terminal and connect an alligator clip to the other ends. The length of the wire doesn't really matter. Ours is long enough to allow you to sit in the car and watch the pressure gauge while adjusting the pot. Unplug the Sender Unit and clip one potentiometer wire to the wire which comes from the pressure gauge. Clip the other potentiometer wire to a handy earth point. Turn the ignition on and the gauge pointer should move while adjusting the pot. Ours read 600 Kpa when the resistance was 53 ohms.
If you need to buy a new Sender Unit, there are no after - market ones available. A genuine one will cost $160.
You didn't say if your low oil pressure light came on at low revs. I don't know at what pressure it should come on at, but a Holden Workshop may be able to tell you.
Its switch can also be checked. Turn the ignition off and unplug the switch wire. There should be no resistance between the switch terminal and earth. Start the engine. The switch should be open circuit. Touch the wire to earth while the ignition is turned on. The oil pressure light should come on.
I hope this all helps.
AnswerID: 20174

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