Sudden Loss of Engine Oil Pressure At Idle -
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post #1 of 9 Old 08-26-2004, 02:42 PM Thread Starter
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Sudden Loss of Engine Oil Pressure At Idle

Sudden loss of engine oil pressure at idle

I have owned a 1997 Wrangler with 4.0L engine for about 6,000 miles.
1. It has 75K miles on it and based on appearance and maintenance records appears to have been very well maintained with oil changes done religiously at 5K mile intervals.
2. The vehicle normally operates with 40 psi of oil pressure at 2K RPMs and about 210 degrees of temp.
3. At idle and when warm the car normally shows some where between 15 psi and 20 psi of oil pressure at about 700 to 800 RPMs.
4. I have over the last few weeks I have had occasions when while sitting at idle and with no apparent loss of engine speed the oil pressure will suddenly drop and the check gages light and alarm will sound. This condition will go away with a slight increase in RPMs.

Has anyone else experienced this and can anyone explain it or suggest a fix.

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post #2 of 9 Old 08-26-2004, 02:56 PM
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My 97' did that all the time......bad oil pressure sender.....

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post #3 of 9 Old 08-26-2004, 08:27 PM
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Originally Posted by Grimmjpr
My 97' did that all the time......bad oil pressure sender.....
I agree bad sender, or a short in the senders wiring....mine did the same thing with 75,000 miles on it....

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post #4 of 9 Old 08-26-2004, 10:26 PM
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Yeah, you might have some loose connections in your cluster. Just take it out and clean off all the connections and make sure they are plugged in. That will probably make the problem go away.

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post #5 of 9 Old 08-26-2004, 11:03 PM
Jerry Bransford
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99.99999999999% it's just a bad oil pressure sender. They have a reputation for doing that at the worst possible time, scaring the bejeesus out of you... like it did to me at 1am on a long lonely deserted desert road. My TJ was still nearly new at the time and it made me think the engine was going to crap out on me 50 miles from nowhere. A new sender fixed it permanently... it's been fine for 110K miles now.

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post #6 of 9 Old 08-26-2004, 11:11 PM
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Yep, Mine would drop to 0 psi at idle. Scared the crap outta me!! Replaced the oil pressure sending unit, and now it sits happy at 20 psi at idle.

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post #7 of 9 Old 08-26-2004, 11:22 PM
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Thanks so much for starting this thread. I just had this happen TODAY for the first time on my Jeep, and I was wondering what was going on, although it is the lesser of two problems. At least it is a quick fix. Cool.
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post #8 of 9 Old 08-27-2004, 03:39 AM
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Same problem here except it has continued after replacement of the oil sensor. It only happens once in a while after the temp reaches about 210F and when ideling. The oil pressure is slow to response when the rpm is increased but usually runs 40 plus under road conditions. Water pump failed at 107K miles so replaced radiator and hoses while I was in there.
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post #9 of 9 Old 08-27-2004, 08:42 AM
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another vote for bad sender

I had the same thing happen on my 97 TJ (2.5L) about two years ago. Although several people advised me that it was a bad oil pressure sender, I somehow reasoned that it was a bad oil pump and changed it.

That didn't help.

Shortly after the pump swap I started dumping oil as I was driving. It left a thick black cloud behind me. The pressure sender had ruptured and was spewing oil onto my exhaust manifold/pipe.

So, I'll second/third/fourth the votes for the sender as the offending item.
The good news is that those are cheap and take 5 minutes to change, if you are slow.
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