Impending doom? Or cleaned-out engine? (long!)

My engine is either cleaned out, or on it's way out.

It's a 1994 Cherokee XJ, with the 4.0 H.O. I-6, automatic with command trac. I've owned it for a little over eight months now, and before I bought it the Jeep sat in a field for six months. The Jeep has 194 thousand miles on it, or 310 thousand kilometres, and runs quite well. Unlike most other 4 litres I've known, the Jeep has never knocked, leaked, or had any trouble starting.

Since I bought it and put it on the road, I've changed the oil twice; the first time I ran it for 3200 kms then flushed it with a little tranny fluid, and changed it. The filter I used was a K&N filter, and the oil was Valvoline Max Life. Over the 3200 kms, the Jeep only used about half a litre of oil. Just before I changed the oil, my oil pressure had begun to drop slowly. It dropped 5-10 psi across the board, but never below 15-18 psi at hot idle. When I changed the oil and filter, I noticed that the filter was unusually heavy. I replaced the oil with Valvoline Max Life Synthetic, and a Wix brand filter.

Last Sunday, (500 miles/800 kms after the last oil change) I came back from a mid-length jaunt at highway speeds and, in preparation for a much longer journey, checked the oil/other engine fluids. I found there was some sort of sludge on the tip of the dipstick, and noticed that she was making the typical diesel-ish clatter of what most assume is a typical 4.0 Jeep engine. Of course when I saw the sludge, I thought my head gasket had sprung a leak; so I checked the oil fill cap and found not a trace of the usual mayonnaise/milkshake most of us dread to find. My coolant was low, but nicely green with no trace of oil. Still freaking out, I rode along with a friend instead of risking my engine for the trip.

I have since topped up the coolant, and driven the Jeep around town a few times. The clatter hasn't gotten worse, the sludge has diminished slightly, and the coolant is still clear. There's no mayo/shake anywhere you'd expect to find it and to top it all off, my oil pressure has never been better! When under load, the engine purrs along without any trouble. It doesn't overheat, and has plenty of power. (The trips I took were unavoidable; going to the store to get new oil/filter, and taking care of obligations.)

I changed the oil and filter today, and the old oil looked pretty clean. (A dark gold/reddish colour, no foam/sludge.) I replaced it with standard Max Life, and another Wix brand filter. Yes I also added some Lucas oil conditioner, which many folks on-line hate, but all the mechanics I talk to like to run in their engines.

My question, after my long and sordid tale, is this; Do these signs (new clatter and sludge on tip of dipstick) point to impending doom a la popped head gasket? Or do any of you think I might have cleared out some old sludge/crap/whatever, and now the Jeep is running like a 4.0 should run? I'm seriously strapped for cash, (on a fixed income) and the thought of having to drop a new/used engine in is terrifying to me. I'm keeping a close eye on it, hoping that the fresh oil and filter will make everything all better...

What do you folks think? Has this happened to any of you?

You could have cleaned out and loosened some of the gunk that was in there. You should run some seafoam through it when you do the oil next time. I noticed that my engine sounds a little "louder" when I run some cleaner through it. It also seems a bit louder whin I have in a 5-30 or 10-30 weight oil in. I use 20/50 when it hit 70F here in KC. I know a guy who puts a quart of straight 90w in his during the summer and he never has a problem. But I wouldn't do that.

X2 on the SeaFoam (or Rislone, or Auto-Rx). I just switched to synthetic last oil change and instantly noticed more engine clatter, due to the thinner oil. I'll be switching back to Castrol GTX next change....

As far as your head gasket....as long as your engine temps are good, you should be fine. It's my understanding that overheating leads to a cracked head and/or blown head gasket....if I'm wrong, I'm sure someone will quickly correct me!

I'm sure that ATF you put in cleaned up a bunch of sludge, that stuff is pretty high detergent....

Thanks for the input guys!

I used the type F tranny fluid. After some research here, the consensus seemed to be that this type had the most detergent in it. I didn't add much, maybe half a litre/quart, and drove it for 36 kms/22 miles. (Highway driving, with some stop-n-go minor city distance.)

I'll drive it around some more Friday, and take it out on the highway to see what shakes loose.

And Lucas Oil Stabilizer is awesome stuff. When I go back to Castrol, I'll be using Lucas as well....

Try some Marvel too.

Marvel Mystery Oil?

I'll give that on a try next oil change. I've heard good things about that too...

I don't know if driving it is such a good idea with the ATF in there, usually with an ATF or Kero flush you just let it idle for a while, not run around with it it's not a good idea to put a load on the bearings with cleaners like that in there. Either way the high detergent and the synthetic will break down the sludge, atf or kero will break it down fast. Even after changing the oil the cleaners you used are still soaked into the crud thats in there and are still working. One of the reasons I always recommend that after flushing you keep an eye on the dipstick and when you can't read the stick thru the oil you change the filter. For that I use cheaper filters, Mopar OEM's, not my expensive K&N's or Mobil-1's though for me that has not been an issue as all our jeeps run Mobil-1 and after about 3 oil/filter changes on the used TJ's sludge is no longer an issue though I did use about 6 Mopar OEM filters on each one during that period. As long as the filter can clean the crud out the oil should still be fine for a normal period of time.

Gotcha... Mental note; when 'flushing' my engine with tranny fluid, don't drive it. (When I was originally told about this 'trick' I was instructed to "drive it for either an hour, or 100 kilometres; get it good and hot!")

I switched from the synthetic to regular dino juice because (I'll admit) I panicked and thought about all of the posts I saw saying how modern oils (especially some synthetics) don't have enough zinc (or something) to protect the camshaft. Maybe next oil change I'll try the synthetic again...

As for the MMO, do you drain the oil and replace half a bottle/full bottle of regular oil with the same amount of MMO?

Another question: I've heard about some folks cutting open their filters to see what's going on in their engine oil system. So far, I haven't really seen how these folks are doing it. I don't think a hacksaw would be good because it'd get metal shavings all over the filter. A think a grinder/cut-off wheel would be bad because of sparks. Any advice on this? Should I not bother? Mostly, I'd like to look inside the K&N filter to see why it was so heavy...

there is a tool to do it, looks like a big can opener, and cuts the rolled lip off the bottom.

I use an old set of tin snips.. It's not safe, and it's not terribly effiecient, but ti works.
Make sure you don't cut your fingers off.

XJPhoenix said:

Gotcha... Mental note; when 'flushing' my engine with tranny fluid, don't drive it. (When I was originally told about this 'trick' I was instructed to "drive it for either an hour, or 100 kilometres; get it good and hot!")

As for the MMO, do you drain the oil and replace half a bottle/full bottle of regular oil with the same amount of MMO?

Click to expand...

Put MMO in your engine as if it were regular oil, like usual and make sure you fill the oil to the correct level and run it like that till your next oil change. I would run half a bottle at a time that way you get two treatments and don't change the viscosity that much.
-Sam

Hacksaw should be fine......you'll still be able to see why it's so damn heavy even with the small amount of shavings from the sawing.

Hmm...

I'll try the tin snips first, (in a vise, fingers far away from the blades!) and if it's crunky I'll hacksaw it off. If I find anything I'll post some piccies!

Is the MMO like the Lucas additive? Thick as all get out?

MMO isn't thick.

I haven't used Lucas yet, so I'm not sure how it is.......but I will for the next oil change in a few hundred miles