mikesweet33

Good evening everyone. Thank you for reading my post, and I will try to keep it as concise, yet detailed as possible. I am hoping some knowledgeable people can help to confirm my theory, or help point me in the right direction to troubleshoot this and get me back on the road.

Pertinent information:
-2001 XJ Cherokee 4.0, 5 Speed Manual, only 110,000 miles
-NO check engine light (**99% of the time with the exception of a misfire code in the summer from repeated injector heat soak on startup) But for now no check engine.
-Fantastic oil pressure. Sustained 50PSI while foot is on accelerator all the way to oil change interval
-No knock. Sounds like every other 4.0 to me. Has sounded the same since I bought the jeep 20k miles ago.
-Metal flakes are NOT magnetic

Yesterday I changed my oil. Drain pain washed thoroughly before draining the oil. The oil is very metallic - like a brown WKII Grand Cherokee pain job with metallic flake in it. No large flakes - just a handful of slightly larger flakes. Here is a picture (general metallic effect hard to see, larger flakes very easy to see):


This was not the first time I noticed metal in the oil, and it is approximately the same amount of metal in the oil as when I first noticed months ago (maybe less metal even). The first time I noticed was August, 2018. I was alarmed and drew the following potential explanations:
-Early signs of main bearing/rod bearing failure?
-Timing chain scraping timing cover?
-Intermittent knocking from heat soaked injectors, causing intermittent damage to rod bearings?

However due to no CEL, no knock, no other symptoms I kept driving it. In fact drove From Denver to NY, then back to Denver - zero issues at all.

Today: I pulled the pan to check for damage bearing damage (**This pan was an aftermarket made in canada brand I cant remember pan I installed 11/17). Nothing I can report. Wiggled all the rod caps and found zero play whatsoever. Nothing to report from the main bearings either. What I could see of each cylinder looked excellent. Camshaft looked great and what I could see of the cam bearings seemed to be no issue. Zero metal in the oil pickup. Looked so good I didn't even take a picture. SOME dirt at the bottom of the oil pan but I believe it was from the filthy engine block, and monkeying the pan itself over the front axle, and my dirty hands. No excess metal, or larger shavings. One weird piece of wire that almost looks like solder:



My last item is my main theory, which is the timing chain slack. 110,000 miles seems to few for the timing set to have any issues, or have enough slack to hit the cover. BUT, the chain itself seems to be sloppy. As you turn the crank, the slack does not stay consistent. it varies from very taught to very sloppy. I recall seeing on my scan tool the timing was quite far advanced (-22º on acceleration comes to mind?) if that makes any difference. Wont be able to check til the pan goes back on.










So anyone who read this far and would like to weigh in what do you think? Is it at all possible for an engine with 110K have a chain wear down the timing cover? What am I missing, that could be grenading inside my engine?
Tomorrow I'll pull the timing cover and see if I can find any witness marks inside, or evidence of this failure.

-Mike

GreaseMonkey17

BMAC6642

I put a Cloyes 200-9-3127 timing chain in my 1987, advanced the cam 4 degrees and had a big low end power improvement in my 210,000 mile engine. The chains not cheap but I will be able to use it in my next engine.

mikesweet33

Not looking for any performance increase. I just want to know why there is metal in my oil. Currently still working on getting the cover off. A little more difficult than expected.

mikesweet33

Managed to pull the cover today. There appears to be a clear outline of the chain MAYBE brushing up against the cover. Certainly not concrete evidence of grinding. And I would think it would scrape all the carbon off the cover where they're contacting. Maybe the timing gear alone is responsible for some metal debris, with the excess slack on the chain.

Well the chain is definitely worn out at least so Ill fix that with a new timing set.I guess we'll see where we stand in 5000 miles.