I have never ran SF through the intake, via vacuum line, or otherwise, so I cannot speak to that. What I do with SF is run it in my oil, idling in the driveway, right before an oil change. I usually only do this with recently purchased used vehicles. I gives me piece of mind, knowing that the engine crank case is as clean as it can be. I do this until I feel good about it, really, which is usually 3 or 4 times, and 2 bottles. I pour half a bottle in, before the oil change. When I can check the oil, and it's clean looking, after a couple thousand miles, I know it's done. HTH!!

My Jeep didn't smoke one bit with the Seafoam in it, but as I said, I know my engine is extremely gummed up and nasty inside. Just from looking into the oil fill on top of the valve cover I can see that it's pretty nasty inside. I did an oil change Monday, and the quart of oil I drained out yesterday to add the MMO was 100% jet black already. After running the MMO my motor makes substantially less noise, but It's still present. Last night I ran the Jeep 71 miles after adding the MMO and it purred like a kitten the entire way after about two minutes of running. Today I drove to work and back and It's starting to make more and more noise. Thank you to all who suggested MMO, you atleast gave me one less 5am bike ride to work. It's amazing how cold 26 degrees is when you're riding a bmx bike down hill doing atleast 50.

(I know I'm doing atleast 50 because the speed limit is 45, which most people don't follow anyway, and I pass cars riding down the hill. Then I stop at the 7/11, grab a hot coffee, stand in front of the door with the heater until I stop shaking, then get back on my bike.)

sound like a lifter leaking down if it was a stuck valve you would no when it either bent and broke poped a hole in the pistion or bent a push tube try the marve oil

Here's an update...

I ran that marvel mystery oil through the Jeep and it purred like a kitten. Over the last few days the noise has come back, but with a slight twist. The noise comes and goes in a pattern that sounds like the timing is off. (It wont do it for 5-6 seconds, then it will do it for 6-7 seconds, then it wont for 5-6 seconds, and so on.) Today while I was sitting at a traffic light, I noticed my exhaust started to pulse pretty bad like a bad idle surge. When I pulled away from that light the Jeep bucked and fell on it's face. I popped it into neutral, shut it down, and started it back up. The problem lessened, and slowly went away. Can bad timing cause these types of noises? Anything special I need to know about adjusting the timing on these things?

sounds like you have a vacuum leak(s), which would explain the surging. Check every line, especially the manifold lines for dryrotting and cracks/breaks. Also make sure where they connect is not loose.

Ugh....... I'm soooo horrible with vacuum stuff. What are the vacuum lines on this thing and how do I check them? I know nothing about the vacuum systems on an engine, but I do know what vacuum is, if that means anything.

Believe it or not, you're not the first person to tell me the Jeep might have a vacuum leak. Now that I think about it, that might explain why my brakes suck so bad. My brake pedal goes to the floor all the time, and I have new pads, rotors, shoes, and wheel cylinders. If I rev the Jeep up pretty high, my brake pedal is much more responsive. After shutting the Jeep off, my pedal will get stiff after 1.5-2 pumps. Sound like it could be the problem? Like I said, I know nothing about a vehicles vacuum system.



P.S. Happy Thanksgiving... (No turkey smiley????)

When its making the noise try pulling an injector wire plug,one at a time to see if it gets worse ,if your injectors are miss firing that cylinder will be lean and possibley have a lean knock

not necessary, if that was the problem, he would have a check engine light on.

You can NOT adjust the timing, timing is controled by the Computer

You have mentioned, removing a quart of oil to add the marvel and it was black, this is telling you this is the problem, its obvious you have sludge in the crankcase and valve train, I would drop the oil pan clean out the sludge, take the valve cover off and inspect valve springs etc. Clean clean clean, the reason why you have sludge is lack of oil changes

While you have the oil pan down, you should go ahead and put a new oil pump in as well, it is full of sludge

Lack of oil changes has never been a problem. The previous owner (Family) bought it pre owned from a dealer fresh off a two year lease and owned it until 2006 when it was given to me. Previous owner got the oil changed at the dealer every 3000 miles at the most, and I change the oil every two months at the most (Because it's so black.) Can the pan be pulled with the motor still mounted in the Jeep or does it need to be pulled?

The pan can be romoved with the engine in the vehicle, you will have to remove the passenger side motor mount to get to 2 or 3 bolts for the oil pan, you have to put a jack under the tranny to compensate for the motor mount being removed. Its worth the $25.00 for the Haynes manual

Here is some info on Sludge


http://www.schleeter.com/oil-sludge.htm

Marvel Mystery Oil RULES! I submerged a 350 boat engine in salt water once. Dried it out, put MMO down the cylinders. It started right up and I ran it anothe 3 years. Add it to your oil, run it a few hundred miles then change oil with a can of STP. I bet it will solve your problem.

I threw out my haynes manual. It showed to be worthless for my '94 cherokee. The brake diagrams were completely different from my setup, the steering diagrams didn't match my year xj, and none of the wiring diagrams worked with my xj, they were all '97+. I sent a complaint to haynes about a year after buying the manual and they told me they would be glad to refund my money is I sent them the book and original receipt and I paid for shipping. Who keeps the receipt for a book a year after you buy it??? Long story short... I will be buying a chiltons online since they aren't sold anywhere local. Thanks for the info though. Would you recommend using form a gasket for the pan and valve cover or buying the gaskets for $19.99 a piece?

I usually buy the gasket set

Ok, thanks for all the info. Brake cleaner to clean out the sludge?