Oil pressure questions

[Akula69]

I realize there have been several folks here that have had oil pressure issues, and after searching the threads I still have a couple of questions.

 

First, I have the 89 4.0L with 269,000 on the clock. The PO told me the lower (block) engine had been gone through in the last 25K miles with a new crank, bearings and a high volume oil pump.

 

I have not has the pan off to check (and the PO could not find the paperwok for the re-build), but after I replaced the dash cluster several days ago I have been watching the oil pressure gauge and have noticed the following:

 

With new 10-40 oil and a Fram (yes I know, :roll: I had it on the shelf already) I get:

 

65-70 PSI at cold start

60 PSI at idle after 4-5 minutes that surges to 65 PSI upon application of throttle

30-40 PSI at idle (in gear) after 15 minutes that surges to 65 PSI upon application of throttle

 

Can anyone advise if these are normal? I wonder if under throttle the 65 PSI will be a bit high for the main seals... :dunno:

 

Thanks

[summerinmaine]

I realize there have been several folks here that have had oil pressure issues, and after searching the threads I still have a couple of questions.

 

First, I have the 89 4.0L with 269,000 on the clock. The PO told me the lower (block) engine had been gone through in the last 25K miles with a new crank, bearings and a high volume oil pump.

 

I have not has the pan off to check (and the PO could not find the paperwok for the re-build), but after I replaced the dash cluster several days ago I have been watching the oil pressure gauge and have noticed the following:

 

With new 10-40 oil and a Fram (yes I know, :roll: I had it on the shelf already) I get:

 

65-70 PSI at cold start

60 PSI at idle after 4-5 minutes that surges to 65 PSI upon application of throttle

30-40 PSI at idle (in gear) after 15 minutes that surges to 65 PSI upon application of throttle

 

Can anyone advise if these are normal? I wonder if under throttle the 65 PSI will be a bit high for the main seals... :dunno:

 

Thanks

 

Sounds as good as or better than "normal" to me. If you're worried about the high end, have you tried a lighter grade oil (and a better filter of course)?

[Eagle]

Very high. Check with a known-accurate mechanical guage to verify the readings.

 

And dump the Fram filter. So you had a $3.00 filter on the shelf. Is it worth blowing a $2,500 engine to save $3.00 on an oil filter? Yes, Fram filters are THAT bad.

 

Factory spec for a warm engine is 13 psi minimum at idle, and 37 to 73 psi above 1600 RPM. Most 4.0L engines in good condition tend to run about 50 psi (+/- 5) at highway cruise. My '88 XJ with 279,000 on the clock still runs at about 45 psi using Castrol 5W50 synthetic.

[BLHTAZ]

Very high. Check with a known-accurate mechanical guage to verify the readings.

 

And dump the Fram filter. So you had a $3.00 filter on the shelf. Is it worth blowing a $2,500 engine to save $3.00 on an oil filter? Yes, Fram filters are THAT bad.

 

Factory spec for a warm engine is 13 psi minimum at idle, and 37 to 73 psi above 1600 RPM. Most 4.0L engines in good condition tend to run about 50 psi (+/- 5) at highway cruise. My '88 XJ with 279,000 on the clock still runs at about 45 psi using Castrol 5W50 synthetic.

X2

 

Mine runs at about 35 - 40 when hot at 2000 RPM. When Cold it's at 50+/- using 10w30 AMSOIL. I am going to change it to a little heavier oil soon to see if I can get it to run just a bit higher.

 

Get a mechanical guage on it and verify that ASAP though...