hi, i have a 1997 4,2 and have rebuilt the engine due to gasket failure i have fitted a oil pressure gauge and it has confused me.
it reads 60 psi at 2500rpm just like the book says but at low speeds(revs) it drops and when hot at tick-over it can be as low as 10 psi.
cold it can be 80 psi and breaking in at 1500rpm gives out approx 40 psi.
this has become worrying as it took me 6 months to do the rebuild and lots of money.
if i relied on just the standard pressure guage i would not have given this any thought as it show ok on start-up and tick-over.
do gear driven pumps only deliver more pressure as the revs rise?
thanks bokker UK.

 

Is the guage mechanical or electric? If mechanical,start the engine and loosen the nut at the guage to allow all air from the the line.Dont loosen it much or you'll get an oil bath.If electrical,it could be a bad sending unit.If those two dont fix it,then you have a bad bearing issue.

 

BOF,
Are we sure the readings are, in fact, low???
As he mentioned, without the mechanical gauge, he'd not have had anything to worry about.
I seem to remember the go/no go point for the idiot light (gauge) is about 8 psi.

Bokker, just curious, what weight oil are you running?

I guess I'm not 100% certain there is even a problem (but I could be wrong).

 

Theoretically,you should have 10psi per every 1000 rpm.

 

hi,thanks for both your replyes,oil is 5-30 and the machanical guage shows 40 psi at 2,000 revs hot. this does go up as the revs increase but i am breaking the engine in and have done only 300 miles at max 2500 revs.

thanks bokker, ps i will try to blead the gauge soon and let you know if it works, it sounds like sense to me.

 

hi, tryed to bleed the machanical oil pressure gauge and no sign of air, just oil but it was definately worth trying. iam happier with the readings on the gauge now but still wish i did not have to watch it all the time due to my nerves.

thanks guys bokker.