Who has ever had to replace main bearings due to cracked 0331 head?

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Jan 25, 2012 | 01:31 PM

Omnipotent Octopus

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Year: 00'

Model: Cherokee

Engine: l6 4.0l 242.c.i.

Who has ever had to replace main bearings due to cracked 0331 head?

Is there any way to tell if they are bad other than low PSI?

Jan 25, 2012 | 01:59 PM

hankthetank

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From: Edmonton

Year: 1990

Model: Cherokee

Engine: 4.0

Get on your back and pull that greasy old oil pan off...for starters. Or get an oil analysis...

Jan 25, 2012 | 02:03 PM

kjc

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From: Blue Springs, MO

Year: 1993

Model: Grand Cherokee

Engine: 4.0L Laredo

Quote:

Originally Posted by Omnipotent Octopus

Is there any way to tell if they are bad other than low PSI?

Worn main bearings won't cause lower compression. Worn, sticking valves and/or piston rings will. The only way to know if your mains are worn/damaged is a visual inspection/measuring.

Jan 25, 2012 | 02:38 PM

hankthetank

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Joined: Nov 2011

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From: Edmonton

Year: 1990

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by kjc

Worn main bearings won't cause lower compression. Worn, sticking valves and/or piston rings will. The only way to know if your mains are worn/damaged is a visual inspection/measuring.

I think he means low oil pressure.

Jan 25, 2012 | 02:42 PM

Firestorm500

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Year: 2015, 2012

Model: Grand Cherokee (WK2)

Engine: 3.6L

If you had a cracked head, and are experiencing low oil pressure, I would assume the coolant in the oil wiped the mains.

You need 13 PSI at hot idle, and 10 PSI for every 1000 RPM beyond that.