1994 Jeep Cherokee Low oil pressure

Tiny
JAMIELEEGAUTHIER
  • MEMBER
  • 1994 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 273,500 MILES
Hi guys. Ok I am a mechanic myself but seem to be stumped on this one. My inline 6 4.0L was having low oil pressure and bearing noise. I replaced all the top end and bottom end including oil pump. I did notice though that there is a hole behind the cam sprocket that you can see a push rod. First thing is would this hole there about a nickel size cause my low oil pressure? The engine now has no noise since it is all new. Also I don't burn a drop of oild between oil changes and don't burn any antifreeze either. When I first start up it is sitting at 20-30 and than when it warms up it drops to 4 lbs. I am using 10W30 pennzoil. Any help on this would be appreciated as I don't want to drive it with the low oil and blow out my bearings. When you step on it the oil pressure goes up to 20 lbs or more. HELP! I am completely at a loss. Thanks in advance for any help here. Oh yeah I am using a mechanical gauge for the reading also.
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Wednesday, June 25th, 2008 AT 9:29 PM

3 Replies

Tiny
RASMATAZ
  • MEMBER
CAUSES OF LOW OIL PRESSURE

Possible culprits include:

Excessive main and rod bearing clearances (someone may have installed the wrong-sized bearings or standard-sized bearings on a reground crankshaft). Only 0.001-inch of extra clearance in the main bearings can reduce oil pressure up to 20 percent!

Excessive camshaft bearing clearances (a bearing may have slipped out of place when the cam was installed).

Excessive clearances inside the oil pump.

Leaks between the oil pump and engine.

Oil pump relief valve stuck open or installed backward.

A loose or mispositioned oil pickup tube (too high in oil pan).

A defective oil pressure sending unit or oil pressure gauge.

Low oil level in the oil pan.

Cracks or leaks in the oil galleries or gallery plugs.

Cracked oil pump housing (improper installation).

Oil viscosity too thin for hot weather.
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Thursday, June 26th, 2008 AT 6:52 AM
Tiny
JAMIELEEGAUTHIER
  • MEMBER
Well my engine gets actually 65 plus psi at start up but it drops to 4lbs at idle after a half hour.
It drops slowly.
Here is what is all new on it:
New Cam
New Crank
New main beairings
New connecting rod bearings
New oil pump
New water pump
New hoses
New valve springs
New Lifters
New push rods
New Rocker arms
New Bridges
New pivots
New timing chain and Sprockets
SO what do we think this is? I am wondering if it is my cam bearings or not?
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Thursday, June 26th, 2008 AT 9:40 AM
Tiny
RASMATAZ
  • MEMBER
Did you install a crankshaft kit-or you have the crank reground and use undersize bearings?
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Thursday, June 26th, 2008 AT 2:23 PM

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