Evanfordsp1

Hello, I have a 2000 model Cherokee Limited, i bought it about 2 weeks ago, it is in very good shape- body and frame and engine wise(so far). But recently i have changed the engine oil in it, and im not sure if the tapping noize was present before or after the change but the tapping is very noticable.

Heres the specs so far:
2000 Cherokee 4.0 I6
Running Mobil One 5W-30 synthetic oil (just changed)
Everything else motor wise is stock so far as i have found
142000 miles on it

It has started to tap, in a loud(but not too loud) tone. It seems to me that the tapping conitinues even once the engine has warmed up and while running for a while. I cant tell if the noize gets faster when the rpms go up (but if that is a sign i will surely check). From inside the jeep with the doors closed the tapping/knocking is heard, but not too loud. The only thing i can say it sounds like is a deisel truck runnning when ideling. It seems to me that the noize is comming from the top of the motor, and when you walk around it the noize becomes quieter in some places and louder in others(with the hood up of course).

But before i bought the jeep, it had been sitting for a year or so, and had not been driven to much from the previous owner. I am wondering if the prolonged sitting may have lead to this problem.....

But, i am very stumped, i am pretty mechinically inclined, but am wondering what yall think may be the problem before i start tearing the engine apart. But, i would like to know if there are anyways to find out what the problem is, and fix it simply. But, i would also like to know if there is any store bought cleaners or aditives that may help me find the answer.

Thanks, and detailed answers are greatly needed, Thanks again...

Firestorm500

It is probably either a stuck lifter or one that is losing it's prime.

Your engine may not like Mobil 1. You should be running 10W30 anyway I believe. Check your owner's manual.

You may have to drain the Mobil 1 out and change the filter. Put back in a good conventional oil in the proper viscosity and a new quality filter, such as Mopar or Wix.

Keep the Mobil 1 for your lawnmower.

If it still clatters, professional diagnostics are in order. You may up tearing down the engine to get to the lifters.

Evanfordsp1

Yeah i myslef do not like the idea of running Mobil 1 in it, but the last owner bought the car brand new off the lot and he ran it since day one, so i am reallt reluctant to run a different oil in it, it sounds to me like to much of a change fro the motor to withstand. But i am wanting to switch over to Mobil 1 10W-30 anyways, but that is planned for the next oil change. But if it a stuck lifter is there any products that can (unstick) the lifter, and have it running back to normal again.

Is there ant other things that the sound may be coming from, maybe a injector or rod or valve, and any easy fixes.

-Thanks

TheKirbyMan

Is there a way you can post a video and let us hear the noise?

Evanfordsp1

Yes i can, i will post a video soon, but until then, i have poured a bottle of Gumout Fuel Injector Cleaner hoping that it will lighten the noise if it may possibly be a injector tapping. But, if that does not lessen the problem, is there any other additives that can help identify the problem.

Firestorm500

Money, time, and elbow grease. Unfortunately.

Your original post didn't mention that the previous owner was already running Mobil 1. So I would leave it in. The difference between 5W and 10W is minor. Once the engine is warmed up, it's all 30 weight anyway.

I don't think that pouring bottles of chemicals into it is going to fix it. A waste of time and money. But I hope I'm wrong.

Evanfordsp1

Yeah I believe that's gonna be my only option at this point. But I'm stumped about where the noise is coming from. Because I seems like the noise will go away after a while of running. I'm really desperate at this point.

TheKirbyMan

Mine makes a little noise, almost sounds like a little bitty diesel...from what I understand, it's the transmission pump running. I've heard alot of Jeeps make the same noise and they're running fine.

Once we hear the video then hopefully we can figure out what the sound is.

And +1 on the additives, it's not going to do much. If you use something like Lucas or Marvel Mystery Oil it might make a little difference, but if anything it'd be a band-aid.

wildspear

Get a chunk of garden hose (3 or 4 feet) place one end on different parts of the engine and the other end to your ear. Try to oin point the noise. I had a noise and I thought it was a loose flex plate bolt or a cracked flex plate. It turned out to be a busted wrist pin, I only know this because the rod beat the snot out of the piston and it ended up in the bottom of the oil pan. Find out where the noise is coming from and then you can start the process of narrowing it down.

Evanfordsp1

I got to say thank you for the responses, but i will post a video shortly, but today as i cranked it up i noticed that the tapping/knocking is actually louder when the motor is first started, but once the engine warms up and you run it for a while the noise seems to become quieter, and at this point i cannot tell whether the noise gets faster when the rpms go up or no, but i figured that the added information may help those who are much more engine knowledgeable than me to find a source to the tapping/knocking.

But i have talked to a few buddies of mine, and they all say that there 4.0 jeeps all make weird noises from time to time, but i cant say that when i first bought the jeep; that i noticed the sound, it seems like it all started after the first week of driving it and changing the oil and oil filter.

But thanks again, and all comments are greatly appreciated...

TheKirbyMan

Mine does that too. Sometimes if the oil drains back to the pan after sitting overnight, it could make a little valve noise at startup. My '81 F150 does that after it sits a couple days. Goes away after oil pressure builds though.

I listen to Jeeps when I see them around town, and they do seem to have a little noisiness to them....but for an engine that lasts well over 200,000 miles, I'd say a little noise is fine! lol

grantman18

My 2000 that I've had for a few months just started doing the same thing yesterday. It sounds like it's coming from the front of the engine compartment (near the radiator), and it just sounds like a clicking/knocking. Describing it as the sound a large truck makes when idling is spot on. It doesn't seem that the frequency of the knock changes with speed or RPM's. Anyone else have suggestions that weren't listed yet?

Thanks

PJsJeep

x2 mine does this also

Evanfordsp1

Well I'm glad I'm not the only one with this annoying problem. I'm Just hoping that it does not turn into a larger problem. I wish there was a magic answer. Lol.

TheKirbyMan

I'm starting to think that it's just a Jeep thing. And btw my mom's Cherokee (I say mine, but it's actually hers lol, I say mine for easier reference) has like 224K on it and it's made noise since we got it back in like '05 or so. It's never had any problems as a result of the noise.

The fuel injectors do make a little noise, but it's a distinct, high-pitched ticking, nothing like valve tick.

I personally would just drive it as normal and watch fluid levels and keep your ears open to see if the sound gets louder, goes away, etc. You're already putting work into taking care of it so you're already on the right track.