4.0 Oil Pump Longevity

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Sep 30, 2020 | 08:27 PM

#16

318SixPack

CF Veteran

Joined: Aug 2019

Posts: 1,601

Likes: 226

From: East Tennessee

Year: 1996

Model: Cherokee (XJ)

Engine: 242 cui

Does any of the valve train issues (excessive wear, etc) show up in an oil analysis?

Oct 1, 2020 | 05:27 AM

#17

dave1123

Old fart with a wrench

Joined: Nov 2010

Posts: 14,398

Likes: 740

From: Manlius, east of Syracuse, NY

Year: 2000 XJ Sport & WJ Laredo

Model: Grand Cherokee (WJ)

Engine: 4.0L

Only a broken valve spring (one coil) would cause a lifter to not follow the cam, but I'm pretty sure you'd hear that up top from the rocker being loose.

Oct 1, 2020 | 06:34 PM

#18

Idunno

Thread Starter

Seasoned Member

Joined: Jul 2018

Posts: 419

Likes: 59

Model: Cherokee (XJ)

An oil analysis is a good next step. I just changed the oil about 100 miles ago so I'll get a sample of it at next oil change. I change oil quarterly and am currently putting about 8500 miles/year on it. The sound is definitely coming from below the rocker box but I plan to remove the cover and get an eyeball on the condition of the top end in a week or so. A thorough cleaning of the doghouse is in order, anyway.