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Rattling sound from the valve cover


NAXJA Forum User
Hi, Jeepers!

I'm going to start restoring my 1988 Cherokee XJ 4.0L. I have had a rattling noise in the top of the engine ever since buying the car about two years ago. My dad has told me this is nothing to worry about in most cases, but I can't stop thinking about the result if it's something really wrong. I suspect that the rocker arms might be the source of the sound, but it could be a lot of other things as well? Loose bolts, bad valve springs, excessive wear etc. The car has spent 122.000 miles on the road so far.

What else should I look at when restoring the engine?

Thanks !
Arnt H.
122k is nothing...

And yes some valvetrain noise is typical of the 4.0L, as is some noises from down low which is usually 'piston slap'....

Does it sill have good power?
How is the mileage(fuel per liter)?
Use oil?

If the only symptom is noise and nothing else.
I would drive the thing, and turn the stereo up....

An 88 with only 122,000mi. How many years was it in storage, thats less than 10K a year. You could run some engine cleaner thru it, could be a stuck lifter making noise. Add some SeaFoam to the oil or put in a couple of quarts of Mobil-1 or Castrol Syntec the next oil change. I don't know if the 88 was multi-point fuel injection but my 98's injectors make noise, clicking sounds, quieter than a valve tap. My 98 has 173,000mi on it and other than the injector click and power steering doing it's moaning thing when parallel parking it's very quiet.
Hi guys!

I've been out of town for the weekend, and I let my Jeep at home!
It has not lost power, the acceleration is still very good, and the engine does not burn any oil, and the gas milage is at the moment a little high at about 2 liters per 10 kilometers, but that's becouse I havent changed the oxygen sensor yet. I've been running with the faulty sensor for about three weeks. I will change the sensor when it arrives, and put in a high flow cat and a cat back exhaust.
There is not any noise from down below in the engine, but I guess the noise might be a stuck lifter. Can I change the lifter without pulling the engine? I've heard I can get them out by removing the valve cover and using some kind of special tool in the process.
I have had some problems with the rear main seal on the crank, but have changed that, and that's sorted out and does not worry me any more. I have been thinking that by restoring the engine, I won't have to worry about anything breaking down when I least need it.
I have been thinking it might be the injectors making the noise, but havent bought new ones. I guess you wouldn't have bought them here in Norway, becouse the prices on Jeep parts is CRAZY! I think I'll buy new ones on the net next month when the next paycheck arrives...
The car actually haven't been in storage, but the previous owner drove the car very rarely becouse he was 75 years old when he bought the car new in -88. He is my neighbour, and sold the car to me for 2000$ in -00 when he was 87 year old. Then he bought the new Liberty, and keeps telling me that car is not as fun as the Cherokee.........

I'll be looking at the above mentioned itens, and see what I find out.

Arnt H.
Trondheim, Norway
Arnt --

I don't think the noise is injectors, don't rush out to buy those.

Remember that the Cherokee is an overhead valve engine, but not overhead cam. Especially being in Europe, the engines you encounter usually have overhead cams, and these tend to run with less noise from the valve train. Considering the way your XJ was owned and used, it is not likely that the valve springs are damaged or broken -- although you can inspect that visually by removing the valve cover. My '88 has 235,000 miles and the valve train is all original.

What I think is more likely is that you are not accustomed to the noise an XJ engine makes. If the noise is a faint "ticking" kind of noise, I think it is normal. If it is irregular and loud (like a problem associated with only one cylinder), then you need to investigate.

There is no adjustment for the Jeep valves. The rocker arm nuts are tightened down against a shoulder on the stud, and all valve "adjustment" is done by the hydraulic lifters accomodating themselves to the requirements. Sometimes older lifters don't maintain pressure as well as new ones, and this can result in a light "ticking" noise, especially at idle when the oil pressure is lower. It isn't something to worry about.

Another possibility is that the engine was driven so little that one or two lifters have become plugged and won't pump up. This would result in an irregular noise. Driving for a short time with some engine cleaner or synthetic oil might clean that out and restore proper operation.

Unfortunately, the valve lifters cannot be changed without removing the head. You do not need to remove the engine from the vehicle, but you must remove the head from the engine. Obviously, since this requires some work, it would be better to first eliminate other criteria before doing a lifter replacement.
Eagle, Thanks!

Yes I am used to hearing Japanese and European cars, and they are quiet. I know that a pushrod engine like the 4.0L would make a sound like that, but I was just thinking that something might be wrong after all, taking into account that its only 15 years old and has 122K on it. But I the engine is a old design, and this sound don`t really bother me, and it's normal, just like my father said and you, Eagle. I'll try the engine cleaner and see happends.

Thanks again for all the help, folks!

Arnt H. Andresen
Trondheim, Norway