Super sludge in a 4.0 jeep engine, need advice.

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Hello all I'm new to this forum. I've always came here to learn what oil is best for my particular vehicles for a while now though. I just bought a 1997 Jeep Grand Cherokee with a 4.0. It has 162,000 miles on it. I immediately upon buying came here and found that Rotella T-5 10w-30 and a Motocraft FL1A filter was a good combo to go with so I changed to that. Then I found a freeze plug leak.

I ordered new freeze plugs(5) for the side of the block and started disassembly for the job. I figured while I had the intake off I would go ahead and change the valve cover gasket since it would be easy to get to. Yesterday I removed the valve cover to find the worst case of sludge I have ever seen. The previous owner must have never changed the oil. Here is a cell phone picture.

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After posting about it on a jeep enthusiast forum I started cleaning up the valve train with a shop vac and screwdriver to dislodge the sludge and suck it up. I sprayed some brakleen on it to try to free it up better but it didn't really help. Here is some pics after todays clean up.

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Tomorrow I'm gonna pull the rocker arms and give them a wire brush diesel fuel bath one cylinder at a time so I don't mix them up. It will help me clean the head a little bit more too. Have you guys ever seen sludge this bad?

I am worried about the little bit of junk that has fallen down the push rod holes as I cleaned and I'm interested in a diesel fuel flush or something to that effect that can help get all the junk down to the oil pan for a post work oil change. How would you guys recommend I proceed at this point? I've heard of doing multiple short interval oil changes after completing the job. I've had recommendations of using diesel oil for awhile. This site has been very helpful for my research in that past, thats why I wanted to get the opinion of the members here on what I should do next.

Before I started all this work the engine was a smooth runner, granted I've only had it for about two weeks and maybe drove it 20 miles. Thanks for any info you might have for me.
 
Should I try to clean it more than what is shown in the bottom pictures? Is removing and cleaning the rockers even worth it?
 
Originally Posted By: EricF
The engine's definetely a candidate for Kreen..
I wouldn't wait for ARX to work.. holy moly!

Corrected it for you
 
Anything you can take off soaking it is a good idea. Might as well pull the pan and clean the pan and pickup and inspect it.


If you're going to drop the pan can you over fill it with diesel fuel to soak the bottom end since you're going to drain it anyways? Just a thought, I haven't ever tried it.

Pyb with its high calcium is a good choice for short runs, with or without auto rx.
 
Which forum did you post it on?

There is a guy on the NAXJA.org forum (Cherokee specific) who had about the same amount of sludge. He did the same thing you did with the vacuum to try and clean up the top end a bit.

He then used Rotella T 15w40 with a bit of Marvel Mystery Oil to clean up the engine. I believe he used 5 Quarts Rotella T 15w40 and 1 quart Marvel Mystery oil with a Purolator Classic filter. He did short 1,000 - 2,000 mile change intervals and after a few changes his rocker arms started to look cleaner.

The Marvel Mystery mix is a good choice because it cleans gently. Cleaning too fast with seafoam or another aggressive cleaner might clog the oil pickup screen.

I'd say do a few changes with the Rotella/Marvel mix and monitor your oil pressure. That should help.
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I didn't want to pull the pan but the more I research and work on this thing, the more I think I need to . It just seems like a pain on this truck. I think in does need a new oil pan gasket though, I might as well do it while I'm trying to get this vehicles problems ironed out.
 
Originally Posted By: jeepman3071
Which forum did you post it on?



jeepforum.com theres a bunch of really helpful guys over there too.
 
Originally Posted By: Chris142
I think its past the point of cleaning. Id put it back together and run it till it dies if it ever does.


I was kinda thinking this too. The jeep 4.0 is supposed to be tough right? I was planning on taking the vehicle on road trips though. 1,000 mile round trips at the most for work. I want to give the truck as good a shot as possible to have a long life.
 
Oh my word!

Whoever had that thing before you should be flogged.

Well you've discovered the bad news, good news is it will probably keep plugging along quite well. With that kind of sludge I wouldn't try a fast flush, it could dislodge major chunks and cause a serious problem.

Do your manual cleaning then run high detergent oils for short OCI's and realize it's never going to be truly clean without you tearing down the whole thing, but it doesn't have to be either.

If you use an additive the only one I'd recommend to move things along would be MMO, it will dissolve things slowly and that's what you want. But no it's never going to scrub it clean for you and nothing else will either additive wise.

I actually saw pics of a Jeep 2.5 (essentially same engine, two less cylinders) with even worse sludge than that and it was running fine too.

My current Jeep was neglected by the PO and it's grimey inside been running high detergent oils and occasionally MMO for 30k now and progress has been minimal (that I can see) so don't set your hopes too high. Still runs like a top though.
 
I once owned a ford and the prior owner never changed the oil in 80,000 miles. Almost solid coke! I put in a good conventional oil and filter and changed both after about 500 miles three times, and one can of some cleaner. Believe it or not, it came clean. 2 years later I sold it back to the original owner and it was still running strong.
 
Originally Posted By: KCJeep
Oh my word!



Do your manual cleaning then run high detergent oils for short OCI's and realize it's never going to be truly clean without you tearing down the whole thing, but it doesn't have to be either.



What exactly is a high detergent oil, and which one would be best for my 4.0?
 
Sludge on the rocker arms will not hurt a thing, i would button it back up and leave it. I would be more concerned if you ran a harsh solvet based flush through it and loosened up to much at once and blocked the oil pump screen. Myself i would go with short oci's and a good dino oil maybe mix some mmo and go about my business, At this point i'm sure it will run until you get sick of it, or the rest of the jeep falls apart around the engine.

How is the engine running buy the way?? I'm willing to bet if you had never pulled the valve cover and went along with your T5 and the ford filter you would have never known any better.
 
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I would do something like an HDEO or any decent conventional over very short OCIs. My 300 Ford was similarly neglected by a previous owner, and all I did were many short OCIs of 15w-40 and Valvoline MaxLife 5w-30 (for winter), and when it was taken apart for a rebuild, it was appropriately cleaned up.

It was NOT a quick process, though.
 
Originally Posted By: Garak

It was NOT a quick process, though.


Agree. I am not in favor of those "atom bomb" treatments like AutoRX. You're better off doing a bunch of short OCIs with a strong-cleaning oil and just being patient.
 
Originally Posted By: hemitom


How is the engine running buy the way?? I'm willing to bet if you had never pulled the valve cover and went along with your T5 and the ford filter you would have never known any better.


It ran smooth. Just leaked alot of oil at the valve cover and alot of coolant at the freeze plugs.
 
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