spike2450

Hi
I've just purchased my first jeep. A 1998 Cherokee with 81000 on the clock,

I've a problem with zero oil pressure showing on the gauge, i've a new oil pressure switch in the post.
However at idle she seems noisy on the top end, If i look into the rocker cover how much oil should be flowing around i.e. should i get a shower or should there be a steady flow.
How long after starting should you get a good flow of oil up to the valves.

Any opinions would be appreciated.
regards

BlueXJ

That is not a good way to check on the oil pressure or lack thereof. Pull that new sender and replace it (temporarily) with a mechanical gauge. See what you get from that and let us know.
As for it being noisey what type of noise. Valvetrain or bearings or exhaust. Be specific and try to describe the sound ie, tinny or knockng. Does it happen when the engine is hot or cold or all the time, at what RPM, etc...

spike2450

Thanks for the reply. it sounds like a dry valvetrain, which is why i asked about the oil within the rocker cover, the noise happens when she is hot. When i started her tonight it took about 30 seconds or so for oil to be seen within the rocker cover.

It seems as if it has reduced oil flow. When i checked the oil in my diesel van by taking the cap of it's rocker cover i was showered!!

Was just wondering what would be classed as normal at the valves etc.

I have a new pressure sender in the post.

Thanks again.

BlueXJ

Spike I would still try the mechanical gauge to determine if your oil pressure is lower than 15 pounds at hot idle. If it is and the engine truely has the mileage you reported then you may have a clogged pickup screen or a bad pump. You should have a flow with the VC removed but it should not be a shower like on your diesel or even like a normal 350 Chevy. PM XJ Stryker as he may have been running his recently with the VC removed. I have not done that in quite a few years and don't remember it being a lot of oil flow.

5spd-XJ

Once you've determined whether or not you have proper oil flow.(If you do) Try one qt of auto trans fluid and 5 qts of 10-40. drive it around for a few hours (or until your satisfied that the noise is gone, it may even go away if you just let it idle in your driveway) then do an oil change using all proper motor oil. that should not only clean out your engine but it will also free up any sticking valve train. I know it works, I had a customer come in with a S80 that had a clogged oil pick-up tube, and a very loud valve train. after fixing the pick up tube problem I must have changed the oil 3-4 times trying to get it to shut up. Then a fellow tech told me about the quieting capabilities of trans fluid. I knew it was good for cleaning, but wasn't aware that it could quiet up an engine too.

X2 on what Blue said. a mechanical gauge will give you the most accurate reading, eliminating a faulty oil pressure sensor circuit

BlueXJ

5spd is right but determine if you have any oil pressure first. I use diesel fuel in place of the ATF or kerosene works as well. If you have no oil pressure then the oil flush may be detremental to your bearing surfaces. I am overly cautious about bearings but be careful doing the flush w/o oil pressure.

jeeptech

I have seen this several times on 4.0 Jeeps - oil pressure looks good cold and fallls off to 0 when fully warm. This is most often caused by worn cam bearings and the low oil feed to the valve train is also common as oil feed to the upper valve train is supplied from the cam feed. Loose bearings at the cam allow oil to leak past them and no pressure is left to lift oil into the head and the oil pressure sender port screws into the cam feed line as well. Bad news is the motor has to come out for this to be repaired. Sorry!