LittleRed94

The day after I bought my XJ I changed the oil. I had suspicions that the PO had no mechanical inclinations whatsoever and as it turns out I was right. When I drained the oil I was met with 2qts of thick sludge and thats it. I'm talking cold honey is how this stuff flowed. I dropped in 6qts of 10w40 Quaker State. Hoping the thicker oil would help clean up the engine and knock lose gunk. Drove for about 500miles and left at idle for two hours keeping close watch of temperature and oil pressure as I was running thicker oil. Today I decided it was time to get out my "recovery oil" and put in what I consider the good stuff. I drained the oil and added 1qt Lucas oil additive and 5qts Castrol GTX Highmileage (I've got 212,000miles on the engine). In that order. Oh used a FRAM oil filter. Idled the engine while I cleaned tools and picked up trash. After about ten minutes I heard a single knock. Got my attention immediately and I got ready to cut the engine. Went for about 2minutes fine then 3 continuious knocks. At this point I'm worried but it goes quiet again. Lasts about one minute then goes about 5 knocks before I cut the engine. After reading around on here I've seen that knocking after a oil change is "normal" but I'm just overly concerned I guess. Having only about $50 a week to spend on the XJ having to do a rebuild would just be too much for me. So I just wanted to explain my situation as best I could and maybe get some advice from veterans of the "bulletproof" L6 on what my next step should be. Hopefully it's just a it'll go away on it's on problem but if I can do anything to protect my engine that's my goal. I've had vehicles last me 500,000 miles on a single engine and tranny and I plan to do the same on this XJ if I can. Please help. And thank you in advance.

TwistedWrench

Leave that oil in there, and change to a Wix filter. Fram oil filters have been known to be problematic on our beloved six shooters. This might be what's going on, see if that clears it up.

The 4.0 is legendary for its longevivity and durability, and is very forgiving of neglect. However, the sludge you drained out is a sure sign of an owner with the "just keep going till it quits" mentality. And unfortunately no engine can withstand that kind of abuse forever.

If the knock persists, switch back to heavier oil, just don't plan on any road trips. You've got an engine in your future. Rebuild isn't really necessary, as these engines pop up for sale all the time. Find one that hasn't been pulled yet so you can hear it run. Check the dipstick, if its sludge or looks like it was just changed, keep looking.

Good luck!

quneur

Rod knock or loose flex plate bolts. Flex plate bolts would be the simple to fix as the AW4 has a lower shield you can take off to access the bolts. A little locktite on the bolts and reassemble.

LittleRed94

That's disappointing about FRAM, I've always run my cars with those but oh well. Thanks for the info. I did notice a considerable increase in oil pressure compared to before the oil change. Possibly caused by the filter?

LittleRed94

Is a flexbolt tightening an easy task? I'm more of a basic maintenance kind of guy than anything else. I'm sure I can find a walkthrough on here but things never seem to go as easy as it does in the walkthrough.

TwistedWrench

Flex plate bolts are known to work loose, but since the knock started immediately after changing to lighter oil... Not likely going to be the issue.

If you have a head wound, bandaging your feet isn't going to be much help, lol.

And ya, do a search here for "Fram filter" and you'll find countless threads discussing this. Champion plugs and Wix filters are a winning tune up combo for me.

LittleRed94

Did the search on Fram like you said and what a surprise. I've always gone fram. But live and learn I guess. I'll probably end up changing out the filter on my Ford too after those reviews. While reading on the fram I saw recomendations for the Wix 51515. Saying that it adds more filtration due to it's longer canister and adds 1/2qt oil capacity. I think I'll pick one up after work and slap it on there.
Thanks for the advice.
Let you know of the results as soon as I have some.

sycoglitch

Def change out filter. You can do a Napa gold 1515 as well. Oversized filters FTW.

As for the knock. Don't go crazy adding additives and expensive oil just yet. Pull the valve cover off. Inspect first. You def knocked crap loose but.you don't want it going to the wrong places. You may have to run reg conventional and do more frequent changes for a month or two and then go to something like rotella, Mobil etc. There's a worse case you'll have to pull the oil pan but start with the valve cover first. Noggin poke and see what you have to do to your girl

Fred/N0AZZ

^Agreed^


Pull the filter first, replace with a NAPA Silver this time and add a little oil, then start and listen again. Most oils need no additives anymore.


Change the oil and filter (Wix or NAPA Gold) and "Use NO ADDITIVES" for now run a straight 10w30 non syn. Do this for several thousand mi. changing at least every 50-700mi. till all the junk is cleaned out.

sycoglitch

Exactly. And yes, don't get a crazy expensive filter just yet. Even go with purolator. OP, what you want right now is that crap out. It will take time possibly but worth it

DFlintstone

Some info here> https://www.cherokeeforum.com/f51/ho...ocking-125547/

That torque plate knock isn't rare at all, it's a good idea to check those bolts at anytime.

And here> https://www.cherokeeforum.com/f51/ch...xplate-172081/

CCKen

Use a Motorcraft (Ford) FL-1A filter. They're cheap but a good filter.


I would suggest adding some Marvel Mystery Oil but I would be tarred and feathered by this group if I did.

sycoglitch

Lol, not at all. Some rotella and MMO mix is a really good one. I'm more worried of things loose in too much too fast. Rather just try and use oil to get the larger stuff out of possible first.

OP, take a picture of your valve cover when it's off. I can't wait to ser what it looks like

CCKen

Just remove your oil filler cap on the valve cover and look inside. You'll know if you've been had. This is easier (cheaper) than removing the valve cover (at least at first).


If he sees heavy sludge build up through the filler cap, well, what's the plan?

EZEARL

I sure hope the PO didn't put something in the motor to quiet things up until he offed it.


As far as what to do if there is sludge bad under the valve cover? I'd clean as much of it out as I could by hand first plugging up ports to keep it from going down into the motor.. Then do the fresh oil/MMO combo changing it and the filter frequently.