tn_outside2003
NAXJA Forum User
- Location
- Tennessee
2000 XJ with a 4.0. 175,000 miles. New head.
FSM says HOT idle oil pressure at 11 psi is within specs.
Chilton says HOT idle oil pressure at 13 psi is within specs.
(I got this data form forums, NOT the actual manuals.)
My question: Is that number the recommended factory expectation in a good motor, OR is that number the MINIMUM before the motor needs to be rebuilt?
My XJ, when quite hot, after a 35 mile, 80 mph interstate haul, when idling at a red-light, will drop oil pressure down to about 13-20 psi. (It has a new sending unit). Idle at about 600-700 rpm. This is within the specified numbers. If I give it the SLIGHTEST amount of gas (to like 800-900 rpms) the pressure jumps immediately back to 40 psi or above. It runs between 40-50 psi on the Interstate, when driving at 80 mph. There is no engine noise other than a slight lower-end rattle right when started up. Within a couple of minutes it purrs like a kitten. It has a rebuilt, 2005 TUPY head from a Wrangler on it. My mechanic checked my main bearings. They looked smooth and no copper was showing through. They said "your bearings look pretty new." They did not spec them with a micrometer or anything. Their point being....."They look fine....if you lose pressure you will need a rebuild. No reason to spend all day speccing bearings. Could be rod bearings, cam bearings, shaft seats, main bearings... or any combination. So drive it until it loses pressure."
Does this mean that I drive it and forget about it......or consider the pressure at the low range and start saving for a rebuild?
Again...to be clear. My question is: Is my HOT oil pressure in a completely normal, "don't even think about it" range, OR is it indicating a worn engine and a rebuild in the next year or two?"
Thanks,
JG
FSM says HOT idle oil pressure at 11 psi is within specs.
Chilton says HOT idle oil pressure at 13 psi is within specs.
(I got this data form forums, NOT the actual manuals.)
My question: Is that number the recommended factory expectation in a good motor, OR is that number the MINIMUM before the motor needs to be rebuilt?
My XJ, when quite hot, after a 35 mile, 80 mph interstate haul, when idling at a red-light, will drop oil pressure down to about 13-20 psi. (It has a new sending unit). Idle at about 600-700 rpm. This is within the specified numbers. If I give it the SLIGHTEST amount of gas (to like 800-900 rpms) the pressure jumps immediately back to 40 psi or above. It runs between 40-50 psi on the Interstate, when driving at 80 mph. There is no engine noise other than a slight lower-end rattle right when started up. Within a couple of minutes it purrs like a kitten. It has a rebuilt, 2005 TUPY head from a Wrangler on it. My mechanic checked my main bearings. They looked smooth and no copper was showing through. They said "your bearings look pretty new." They did not spec them with a micrometer or anything. Their point being....."They look fine....if you lose pressure you will need a rebuild. No reason to spend all day speccing bearings. Could be rod bearings, cam bearings, shaft seats, main bearings... or any combination. So drive it until it loses pressure."
Does this mean that I drive it and forget about it......or consider the pressure at the low range and start saving for a rebuild?
Again...to be clear. My question is: Is my HOT oil pressure in a completely normal, "don't even think about it" range, OR is it indicating a worn engine and a rebuild in the next year or two?"
Thanks,
JG