Pete M Posted October 18, 2005 Share Posted October 18, 2005 88 MJ, 190k+ mile 4.0L It's sounds like a cross between a bolt being shaken around in a coffee can and a spoon in a garbage disposal. It doesn't have a particular rhythm to it and it isn't obvious as to precisely where it is being emitted from. I've pulled the oil pan and valve cover and everything looks fine. Nothing broken or loose as far as I can tell and no metal shavings in the pan. The worst part is that it's intermittent. During the first occurrence it was persistent at all rpms, the second time only above idle, now it usually only happens for a short time, sometimes only a single thwack. It sorta sounds like the time when my water pump allowed the impeller to eat away at the housing, but I just now went out and pulled the belt off and it still does it. I'm stumped. Short of stripping down the block, any ideas? Anything else you guys need to know? The truck runs fine before, during and after the noise. It doesn't stutter or anything. I need the truck this weekend for the second annual Comanche Club PowWow. I'm flat-towing it to The Badlands, so I only need it to perform when we're there. But I also don't want to have the block blow up on me in the middle of a trail. I can't fix anything if I can't find a problem! : Jeep on! --Pete Some more back story if you want it: It happened a month ago at a local wheeling event. I hadn't gotten a 1/4 mile away from my tent before the noise started. I pulled over but couldn't precisely locate the source of the noise so I told everyone in my group to carry on without me while I limped back to camp to diagnose the problem. I was thinking the starter gear was maybe touching the flywheel so I pulled it. Everything looked fine so I put it back together to try something else, but the noise had now vanished! I took it for a test drive and everything checked out, so I hooked up with the last group. The truck ran great all day. A couple weeks later (maybe 3 miles later as far as the truck knew since I flat towed it home) the noise came back while in an Autozone parking lot. The shmucks inside came out and were stumped (big shocker there). It drove ok last time the noise happened so I figured I could limp the 1/2 mile home. Before the noise was omnipresent, now it only happened above idle so I tried to keep the rpms as low as possible. About half way home the noise suddenly stopped with a quick squealing sound. Now another week has gone by and I've pulled the valve cover and the oil pan. Everything looks nice and tight. The noise happens only occasionally now, but without finding a problem, I can't fix it or predict whether it'll get worse again. :( Link to comment Share on other sites More sharing options...
barnygeroell Posted October 18, 2005 Share Posted October 18, 2005 by the sound description i would say somthing with the cooler blades. probably one of the motormounts broken and now the vblades hits somthing Link to comment Share on other sites More sharing options...
DirtyComanche Posted October 18, 2005 Share Posted October 18, 2005 You said you pulled the belt? So you've narrowed it down to not being your fan or any accessories? How about if there was some crap in your bellhousing that rubs the flywheel or something? Link to comment Share on other sites More sharing options...
87manche Posted October 18, 2005 Share Posted October 18, 2005 Youre sure it comes from the block? I was thinking maybe a throout bearing, or something in the tranny. That's about what my tranny sounds like and it has a bad main shaft bearing. Link to comment Share on other sites More sharing options...
mjeff87 Posted October 18, 2005 Share Posted October 18, 2005 That's what I'm thinking also....something tranny related. I've got a worn out input bearing in the AX5 I swapped in, and in gears 3-5 it makes a rattling "marble in a coffee can" sound if not under load (i.e. coasting or deceleration). It also does it if I put the TC in N and run the trans in those gears while motionless. But, it's a constant sound, not intermittent like yours Pete....maybe your input is just starting to go bad (?) I'm living with mine, hopefully it'll make it thru the winter until the big swap next spring :) It's more annoying than anything..... HTH, Jeff Link to comment Share on other sites More sharing options...
pingpong Posted October 18, 2005 Share Posted October 18, 2005 When I have a mysterious noise that is only intermitten, I start by going over the basics... I Check oil pressure, the do a compreccion check. Then it is on too the visual inspection. I check to make sure nothing is loose in the engine compartment, or under the vehicle. Patrick Link to comment Share on other sites More sharing options...
Pete M Posted October 18, 2005 Author Share Posted October 18, 2005 Oil pressure is good, spark plugs were pulled and they are good too. I haven't done a compression test yet since my kit is missing. Visual tests haven't produced any clues as of yet. The fan was my first thought but nothing is making contact (I don't have a shroud at the moment). I don't have to be moving to have the noise. Just sitting there with the clutch disengaged and the noise may appear. The first time I was driving when it appeared and there was no change as I came to a stop and got out of the truck. I actually wish it would come back. That way I could do a more thorough diagnosis. It's not a "marble" in a coffee can, more like a single large bolt. Right now it usually manifests itself as a single thwack, like a snap. I've had plenty of bearings fail on me and this, well, this is different. I wish I could let you all hear it. :( Some of you may get your chance at the PowWow. I think today I'll put it all back together and try my luck getting it to a mechanic to let him hear it. Knowing my luck the noise will go away. :( Jeep on! --Pete Link to comment Share on other sites More sharing options...
comanchedude Posted October 18, 2005 Share Posted October 18, 2005 Not sure if the sound is the same but I have similar sound when a couple of the rocker arms were getting cockeyed (crooked) due to wear I took them off cleaned them put them back on (field repair) They worked fine for the rest of the day next morning they made that sound again and one went completely 90deg and was off the valve So I replaced all the rockers pushrods and everything was good About a month later i replaced all the lifters as they were noisy Now the engine is very quiet and valve train is very tight So maybe check the play between the rockers and valves if it is very sloppy that could be the problem Just a thought My engine has 188 and the sound is basically what you described Link to comment Share on other sites More sharing options...
summitlt Posted October 19, 2005 Share Posted October 19, 2005 Ive heard something similar when flexplat/TQ bolts come loose. but with yours being a manual not so much. Maybe something in there is just loose enough. I doubt it, but just throwing it out there. Maybe try driving it down the road (I don't want to hear any BS about this) and shutting the truck off (be sure to go back to the on position so you can steer) with the clutch in, if its still there it could be Tcase/tranny related. Link to comment Share on other sites More sharing options...
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