how much oil pressure needed

[rhorner]

my 2.8 t d has low oil pressure at startup that drops away off the gauge after engine is hot .how low is oil pressure in others , 2.8engines.has anyone ever replaced an oil pump on one of these engines

[geeves]

When cold should show 4 on the dial. once warmed up this will drop to 1.5 to 2 at idle but should still be showing 4 by about 1500 revs.
Try changing your oil and filter before anything else but there are several other things that cause low oil pressure. ie internal leaks, bad bearings failed pressure relief etc. Bad maintenance by the original owner has caused the demise of a few of these engines with catastrophic bearing failure around 160000km. Dont drive it if you are unsure of the oil pressure and if you do have to do the pump or bearings do both.
It could also be worth getting a mechanic to check your guage and sender are accurate. Ive never heard of one failing on an isuzu but they are the same make as in nissan patrols which have more faulty oil guages than working ones.

[Yarno]

Is the oil light coming on, if not your gauge may be out...

[rhorner]

i have done the oil & filter , since the gauge does work when cold i might drop the oil pan & check yhe oil pick up filter

[geeves]

If the light goes out verify the gauge is working before dropping the sump. If the light goes out theres an 85% chance its only a gauge fault Super cheap sell cheap mechanical gauges that will bolt in in place of the sender as a test.

[rhorner]

thanks, sounds like a plane

[rhorner]

i mean plan

[munovice]

On my 2.8 1993 td my car starts at max oil pressure and gradually works its way down to the center of the gauge. I thought this was normail as oil heats up the pressure reduced its usually when the motor gets to normal running temperature the oil gets to around 2
Is this normal?

[geeves]

should still show 4 at 2000 rpm once warm. If its showing 2 at idle warm there's nothing worth worrying about