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Old 11-07-2012, 04:16 PM   #1
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4.0 oil pressure

My oil pressure is at 20 once warm at idle. While driving it goes as high as 50. Is this normal for a 4.0. Automatic transmission if it matters.

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Old 11-07-2012, 04:25 PM   #2
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Seems OK to me

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Old 11-07-2012, 04:29 PM   #3
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yep,nothing wrong with that
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Old 11-07-2012, 04:51 PM   #4
Knows a couple things...

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Yep, the engine's true oil pressure rises & falls in direct relationship to the engine RPMs. The oil pump is engine driven so as the engine revs higher, the oil pump pumps harder which raises the oil pressure.

A good rule of thumb for acceptable oil pressure is around 10 psi for ever 1000 engine RPMs.

Caution that newer TJs had their oil pressure gauges reprogrammed so they no longer show the real ups and downs of oil pressure. It was alarming too many new Jeepers who had never had a real oil pressure gauge before they bought their Jeep and didn't know how oil pressure works.
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Old 11-12-2012, 08:44 PM   #5
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Thank you for asking the question. I bought my first jeep (1998 Wrangler Sport) last weekend and the oil pressure fluctuation freaked me out on the way home. But all is well. Oil, plugs and wires have been changed, distributor cap and rotor next as well as trying to tackle the exhaust manifold. Thanks to this forum I think I can handle it.
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Old 11-12-2012, 09:58 PM   #6
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same pressure here. thx for confirmation all is good!

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