getafewlives

Hey guys, I just picked up a 1991 jeep cherokee limited. Everything is pretty good except for a tapping noise that appears to be coming from under the valve cover. Everything still drives fine and feels fine except for the noise.

I am guessing that its a loose rocker arm? I've never dealt with rocker arms before so I am not too sure.

What I want to know is how do I adjust them or find if they are loose? Is it as easy as taking off the valve cover and using a ratchet? Can I take the valve cover off while the engine is running?

Thanks guys

SeriousOffroad

Sounds like a typical 4.0L.

The rockers are not adjustable.

nick_n_ii

Can you get the "custom" rocker bolts like for some Fords?

I just ask cause I thought I had read that some where..

tonyzj93

do not remove valve cover while engine is running. that's a bad idea. you might get lucky and its just a stuck valve. just go to auto store and get some engine flush and try running it through a Couple times. after the 2nd or third time if its still taping. pull the valve cover. you can buy the special cleaner or i've heard some people say deisel works. i also used a small tooth brush to help get the gunk off. just get a gasket get before you pull the cover. and if you leave it off over night cover the valves with a towel to keep dirt and moister out.

McRay

Try running Marvel Mystery oil with a new oil change I have quieted down lifters in some my old cars by doing that.

getafewlives

Thanks guys. I'll try Marvel mystery oil next time I do an oil change on it. It's currently uninsured until the weather gets bad.

getafewlives

Alright, I am almost at the point where the weather is bad enough that I will need to insure this jeep, but I still haven't gotten rid of the noise. I tried rislone or what ever and that didn't help, I also tried adding atf fluid then did an oil change, but its still there. I'm starting to think it isn't coming from the valve cover anymore and more in the bottom end of the back of the engine.

I know it's pretty hard to diagnose something like this over the net, but does anyone have any ideas of where to start diagnosing?

The sound gets faster at higher rpms, and seems to be quieter at start up then gets noisier as I drive. Also the jeep passed emissions with flying colours.

nasonguy

mine sounds like a tap dancer on crack, (well, not really that bad), I think it is just normal for the engines.

BuckB91XJ

My 91 Sport had 185K on the 4.0 HO 5 years ago when I first bought it. It had a "what I call lifter knock" when I bought it. My Jeep now has over 250K on the same 4.0 HO motor. I've driven it daily, driven it to other states and I've 4wheeled the crap out of it. It still gets 18.5 mpg, has plenty of power, blows no blue smoke, runs like a top and still knocks. If you pull your valve cover and don't find anything obviously wrong in the rocker arm/valve spring/push rod area.....I'd slap a new gasket on it, change the oil and filter and call it good. I suppose doing a cylinder compression leak down test wouldn't hurt too.

Ritter4.0

Mine ticks like every other day. So far nothing bad has happened.

alpine.adrenaline

In my experience and opinion (and I think I've heard someone say this before), a ticking Jeep engine is a healthy one. I've heard that tick on several engines and they go years further without any issues. If the noise alone is bothering you, use some Seafoam to try to loosen it up. That stuff is magic elixir for your valvetrain. Pour 1/3 into your crankcase and drive it until the ticking goes away, then change your oil. Tolerate it so that you can time it with your next oil change (you don't want to put too many miles (100ish) on because that seafoam is breaking down sticky deposits). I'm **** about engine noises but those lifters ticking is nothing major.

getafewlives

Hmm I guess I will just leave it and hope nothing blows up haha. Hopefully it won't hurt my resale value too much.

I put a small amount of ATF fluid in with the oil change, this shouldn't hurt anything right? I don't really want to do another oil change.

alpine.adrenaline

I've heard of people adding ATF to the crankcase to reduce ticking. I wouldn't advise it, but XJ engines are bombproof and it'll probably be fine. Seafoam's the way to go, just my 2¢.

jeepers creapers

i have a 2000 cherokee sport 4.0. just replaced head due to the notorious 0331 head cracking! drove jeep for about 1 day and valves started chatering like 100 monkeys with small hammers under valve cover! the other issue is that i drove with the oil pressure gauge reading 0 psi. this sounds very stupid , but before the head replacement this was a common event. i had this checked by a garage and was told everything was fine.got the readings! now chatering is extremely terrible. what should i do ?

notop46

I had an intermittent ticking on one of my lifters. I was able to run the engine with the valve cover off for a few minutes and found the valve with the proplem. The lifter was sticking. Pulled the pushrod out, sprayed WD40 down on the top of the lifter (marvel mystery oil would have been good too), and used a 3/8" steel rod to push on the lifter ro get it to collapse and work the oil in. Put it back together and have been ticking free for a year.