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OIL PRESSURE DROPPED from 40 to 0 slowly at idle

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Old 01-29-2011, 09:04 PM
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Exclamation OIL PRESSURE DROPPED from 40 to 0 slowly at idle

I have a 2002 jeep grand cherokee limited 4.7L v8.. I drove it out to the store today and I put it up in park and my oil pressure slowly dropped from 40 to 0 and my check gauges light came on.. I checked my oil and it was low so I put some in.. It was still reading 0 pressure! But as long as Im giving it gas my oil pressure goes back up to 40.. I got it home and let it idle and the gauge jumps back and forth 0-40.. someone HELP ME! this is my only vehicle I have!!!!!!
Old 01-29-2011, 09:11 PM
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change the oil pressure sending unit.
Old 01-29-2011, 09:31 PM
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Thanks soooo much!


What is the part number for the mechanical oil pressure adapter??
Old 01-29-2011, 09:36 PM
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Change oil and filter if it has not been done in the past 4000 miles. When the viscosity breaks down, it gets thinner as it gets hotter. With an older engine, this can cause the oil pressure to drop to nothing at an idle.
Old 01-29-2011, 09:55 PM
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Alright....
Old 01-29-2011, 10:14 PM
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when it dropped to 0, did the engine make any noises? If not then I would say sending unit, if it did then I would be nervous. Coach
Old 01-30-2011, 12:15 AM
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No it didn't make any noise at all...
Old 01-30-2011, 12:19 AM
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yeah it sounds like the sending unit, especially if its going back and forth like that on the gauge
Old 01-30-2011, 12:22 AM
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Old 01-30-2011, 12:23 AM
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Had the same problem when I bought my 01 xj. If an oil/filter change Dosent fix it, it's the sending unit. Don't let anyone tell you it's a cracked head or gasket issue, as this situation is IMO impossible to actually happen.
Old 01-30-2011, 12:30 AM
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Alright thanks! I already had one jeep dealer tell me that.. Before I got on here and started asking.
Old 01-30-2011, 12:37 AM
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Originally Posted by JeepGrand Cherokee Girl
Alright thanks! I already had one jeep dealer tell me that.. Before I got on here and started asking.
Haha the guys at pepboys said my head gasket was cracked, was seeping oil, and was causing my low oil pressure. Well the oil was because they over tightened my filter the week before when they did my oil, and the sending unit fixed the pressure issue. They also told me it would be 1k$ for an ac compressor change. I know it's a 400$ part new... But ****. Got my mechanic buddy to put in a compressor from a 98 in the junk yard, cleaned and filled it with freon and only cost me 200$. Oh and did I mention the pepboys guy asked me if it was a grand cherokee while we were standing right next to it?? I almost slapped him. Theyre wonderful as a parts store but their service guys dont know ****.
Old 01-30-2011, 01:01 AM
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Originally Posted by notop46
Change oil and filter if it has not been done in the past 4000 miles. When the viscosity breaks down, it gets thinner as it gets hotter. With an older engine, this can cause the oil pressure to drop to nothing at an idle.
Unless hes running synthetic...
Old 01-30-2011, 01:54 AM
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HA HA.. Damn thats bad. I bet you won't go back there for Business!
Old 01-30-2011, 01:55 AM
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No it doesn't have synthetic oil in it right now..


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