I have an 01 TJ with 2.5 and 5-speed with 136000 miles. After engine has been run hard, and shut off, and restarted within 5, or 10 minutes, sometimes oil pressure is slow to pick up, and causes the check gauges light and chime to come on. It will always pick up, but it may take a few seconds, before it does. I am using Castrol high mileage 10W-30 oil, and Fram TG 16 oil filter. Most of time it picks pressure right away, and does not do this during cold weather. I have changed sending unit, but did not cure this. Could this be an oil pump relief valve, or an oil pump problem? It carries 40# oil pressure normally.
Oil Pressure
- Thread starter gvsvic
- Start date
EarthCruzn
New member
I would change oil and filter and go from there. You say it only does it after the engine is hot on restart 5-10 min but not when the engine is dead cold?
I would have a tech or yourself take out the sending unit and hook up a test guage to read directly from the engine. If you are still having slow pressure building up then the oil pump is either;
>Has a clogged screen at the pick-up tube
>Lossing its prime and possibly going out
I have seen oil fluctuation due to too much oil in the engine which will cause cavitation (air bubbles in the oil ).
If the test guage show normal pick-up you sending unit maybe good but the guage is acting up.
I would have a tech or yourself take out the sending unit and hook up a test guage to read directly from the engine. If you are still having slow pressure building up then the oil pump is either;
>Has a clogged screen at the pick-up tube
>Lossing its prime and possibly going out
I have seen oil fluctuation due to too much oil in the engine which will cause cavitation (air bubbles in the oil ).
If the test guage show normal pick-up you sending unit maybe good but the guage is acting up.
Last edited:
SteelHeadz
Super Moderator
I agree with the verification with a manual gauge. The Min. pressure @600rpm should be 13PSI , Min pressure @ idle(800rpm)is 25-35 PSI. The oil pressure releif is set to 75PSI and is non adjustable. If for some reason that there is a debris stuck in the valve, this may cause the oil pressure to drop.
54cj3b
New member
I cant stand those electronic sending units check it for loose wires / ground but if that don't work I'd try a mechanical one more accurate with oil pressure and most likely solve your issue could also try a engine flush to help clean out any gum/sludge build up
unless like earth said your pick up is clogged or your pump is going out
unless like earth said your pick up is clogged or your pump is going out
Thanks guys, I have changed the oil and filter twice since it started doing it, and didn't make any difference. Only does it when oil is really hot. Can the sending unit be all right and the dash gauge do this? It does almost act like the pump loses prime. Could a worn pump cause it to lose prime? It carries 40# oil pressure when running at 2000 rpms, even when oil is hot.
SteelHeadz
Super Moderator
Since you mentioned that you have already changed the oil pressure sending unit, i would rule it out if there's no change in the symptom. There's no telling that the new sending unit is faulty even when it's new but rarely occurs. The oil passages can lose it's prime for multiple reasons; worn camshaft bearings, worn crankshaft bearings, worn main bearings, worn lifters, worn oil pump, worn oil pressure releif spring. Rarely would the gauge be at fault however, if it's in question, ground the signal wire and see if the gauge pegs up to max and 0 when it's open. This is an easy test to confirm your doubts.
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