Wierd oil pressure problem - Drops to 0 at idle! - JeepForum.com

 
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post #1 of 8 Old 11-19-2008, 04:10 PM Thread Starter
Whtfairladyz
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Wierd oil pressure problem - Drops to 0 at idle!

Ok guys, I did some searching. And I have yet to find any kind of answer to point me in the right direction.

My 2000 XJ is having, what I think, is oil pump problems.

Under normal driving conditions, about 99% of the time, my oil pressure is PERFECT. No issues what so ever. Runs about 60 under load and roughly around 25 to 30 cruising... 10 to 15 at idle.

I noticed the other morning going to work while I was sitting in traffic that all of a sudden my CHECK GAUGES light came on and I had 0 oil pressure. I paniced and shut the motor down. I got out and checked everything over and visually, things looked OK.

I started the Jeep back up, perfect oil pressure. After some more head scratching I drove on to work. A few days later, it did it again!

The condition is this....while at idle for more than a minute. My engine's oil pressure drops to 0! However, works perfect at all other points in time. And when the engine drops to 0, you can slightly rev the engine to ~1000rpm and viola! oil pressure comes back. Something else that is wierd...it does not do it all the time. It is sporadic, seeming to do it only when the engine temp is at normal operating temp.

Any advise would be appreciated!

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post #2 of 8 Old 11-19-2008, 04:16 PM
JFM626
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More then likely the sending unit, but if you need to be sure hook up a manual gauge
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post #3 of 8 Old 11-19-2008, 04:36 PM
tjwalker
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The vast percentage of strange oil pressure readings are caused by a faulty oil pressure sending unit as already mentioned. If your oil pressure truly was zero, you'd probably be hearing some engine noises. Some guys just replace them as they're cheap (I recommend buying from Jeep for best gauge mating accuracy) or if you're ambitious, get a hold of a mechanical gauge and temporarily hook it up where the oil pressure sending unit is and compare readings to what you're seeing.

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Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
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post #4 of 8 Old 11-19-2008, 07:53 PM
wheelin79cj
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Yep, Just freaked out today when the wife called and said her oil pressure was at 0. Hooked up the manual gauge and it was perfectly normal. In the process (actually when I first took it out) I noticed that it had a bunch of oil in the electrical plug side of it. Good news to me, I almost had to buy my neighbors Cherokee that has a new bored out 4.0 and a lift already....lol
-Aaron
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post #5 of 8 Old 11-24-2008, 02:28 PM
ArmyFireFighter
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anyone know where to get one of these Manual Gauges?
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post #6 of 8 Old 11-24-2008, 02:42 PM
440_Magnum
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Agree on the sending unit, especially if its OK after a shutdown and restart. They leak oil past the internal diaphragm, and when enough oil builds up on the backside, they read 0 pressure. Turn off, oil forces its way back out and they're good again for a while. Pretty common failure on any vehicle with an electric oil pressure gauge.

That said, NEVER roll the dice with oil pressure. If it really does go to zero, your engine has about a minute (or less) to live without damage if you're driving. A little longer at idle/no load.
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post #7 of 8 Old 11-24-2008, 02:47 PM
440_Magnum
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Quote:
Originally Posted by ArmyFireFighter View Post
anyone know where to get one of these Manual Gauges?
Most good auto parts stores have them.

Here are a few low-end ones from Summit:

http://store.summitracing.com/partde...5&autoview=sku

http://store.summitracing.com/partde...5&autoview=sku


Believe it or not, I've had a few of those cheap Sunpros that have lasted for years. They're not bad at all, considering the low price. Even Pep Boys carries them.

And besides, the cheapest mechanical gauge is more trustworthy (in my opinion anyway) than a much more expensive electrical oil pressure gauge.
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post #8 of 8 Old 11-24-2008, 03:26 PM
ArmyFireFighter
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me and my buddy just gerry riged one from the hardware store. Turns out I will need a oil pump. starting first thing tomorrow,

Wish us luck.
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