MJ Comanche Tech. Stock & Modified. MJ (86-92)
All discussion regarding the Jeep Comanche, the pickup truck related to the Cherokee platform.

Need input on oil pressure

Old 01-16-2019, 05:30 PM
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Model: Cherokee(SJ)
Default Need input on oil pressure

Just got my 1992 4.0 back together after having machine shop do block with new crank and bearings cam bearings, boiled out with new soft plugs.
new oil pump and all. Primed engine oil system and gauge showed 50psi so started engine sounds good no tapping knocking runs and sounds fine.
As it warned up oil pressure drops down to 10 15 psi and finally 0 to 5 at idle. Tried new oil pump, new mechanical gauge, still very low .?????
ANY HELP WOULD BE GREAT. Can I tap in to oil system elsewhere??
Thanks in advance
so no advice? Shop that ground my crankshaft had to turn rod jornals 50 thousands. Mains only 20. Should work they said but super low pressure should not happen, right . Have another one that is 010 on mains and 020 on rods. Don't know what else can cause low pressure condition. Any better ideas would be most appreciated.
Thanks

Last edited by Commanche 92; 02-20-2019 at 09:39 PM. Reason: No input.
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Old 02-21-2019, 09:10 AM
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What is your RPM at idle? Is it a stock cam? Some of the crazy cams will drop oil pressure at idle.
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Old 02-21-2019, 11:18 AM
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What oil and filter are you using?
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Old 02-21-2019, 12:43 PM
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Default Oil pressure.

Idles at 1000 rpm, drops to 800 in gear.
have gone thru three different oil filters. Changed oil three times same issue of low pressure when warm. Tried different oil pump same issue. Checked out all clearances on crank mains and rod bearings. Gonna change crankshaft as I have another with better bearing size' of 020 mains and 010 rods just praying it works.
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Old 02-21-2019, 12:44 PM
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Default Camshaft

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