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wjross 06-20-2012 02:24 PM

help! Intermittent 4.7 oil pressure/coolant issues
Hey guys, i drive a 2000 WJ 4.7 (non HO) with about 170k miles. lately i've had a strange issue that i'm unsure how to pin point. The oil pressure has read very high, in the 65-70 range, where it is typically in the 45-50. this seemed to be resolved when i checked my oil level and found it low nearly a quart (oops). This morning the overhead unit displayed a message that my coolant is low, and my oil pressure gauge was reading in the 75-80 mark. This was on my way to the office and engine temp was at normal. after pulling over, checking oil and restarting i have seen nothing of either issue reappear. i might also mention that this is only a week after my ac compressor locked up, i don't know how or if it could be related but mentioning it won't help. I know some of this is vague, i will be happy to answer questions. Any thoughts or ideas are much appreciated!

hoffmanestates 06-20-2012 07:28 PM

oil pump possibly starting to go out is a hunch I have. don't quote me.just yet

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wjross 06-22-2012 09:52 AM

Re: help! Intermittent 4.7 oil pressure/coolant issues
There is also a sound associated with this problem, one that i don't recognize. The sound is something metal-on-metal friction, a kind of whir. This worries me for fear of damaging the motor, i would be more concerned with low oil pressure but it has never been low

Frango100 06-22-2012 12:20 PM

Re: help! Intermittent 4.7 oil pressure/coolant issues
The high oil pressure would be contrary to a low oil level. Being 1 Qt low should still not give any problems with low oil pressure also.
My guess is the oil pressure sensing unit.
When you had the low coolant level warning, how was the level visually on the overflow reservoir? The sensor can give sometimes wrong level indications after making a turn for example.
The metal noise you hear, is it there with the jeep standing still as well? You need to pinpoint the exact place where the noise is coming from. A mechanics stetoscope would be of a great help to do this.
That you mentioned the AC compressor locked up, did this do anything to the serpentine belt and/or tensioner? The tensioner pulley bearings tend to become dry over time and start making noises and can even become blocked in the worst case. You can easily remove the serpentine belt and spin these pulleys by hand to see if they make noise or have excessive play.

wjross 06-22-2012 02:52 PM

Re: help! Intermittent 4.7 oil pressure/coolant issues
Yes the coolant was low, i added fluid, so that was no biggie. i mentioned it in case that it could somehow have been related.

The noise is present with the vehicle still, in park or in drive, and persists at slow speeds, past so many RPM i can't hear it over my exhaust (glasspack) lol. but the pulley is a good idea, i had not thought to check it out.

wjross 06-22-2012 02:54 PM

Re: help! Intermittent 4.7 oil pressure/coolant issues
and yes the low level, high pressure made absolutely no sense to me. this lends credit to your pressure sensing unit theory

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