Strange noise

[aboyandhisdog]

I've had a noise for a while now that I can't for the life of me determine what it is all about.  It sounds like small rocks in a coffee can or like a metal cap on top of a semi tractor exhaust pipe - those "flappers" that keep the rain out.  Anyway, it's that kind of a metal flapping against metal sound.  It ONLY happens when the accelerator pedal is being "feathered" between accelerating and decelerating.  In other words, foot on the gas - no noise, or, foot off the gas - no noise.  In between - rattle, rattle, rattle.   At first I thought I had a loose heat riser valve that was vibrating but have ruled that out.  I've taken it apart and it is very solid as it should be.  I also wired it in both the open and closed position, and no difference - noise still there.  Also, the jeep needs to be driving - no noise if I'm sitting still and just running the engine.  A mechanic friend of mine threw out the idea of the oil slinger making the noise but, if it was the oil slinger wouldn't it do it all the time?  And, can the oil slinger really be loose like that and what would it be hitting if anything?  That is probably a red herring, but I am at a loss.  Almost everything is new or rebuilt and my 3A runs great.  Strong oil pressure, and all systems normal!  Any ideas???

[Bob W]

Out of phase driveshafts can make all kinds of weird noises like that.

[calvinhunt]

Tom,
 ï¿½You have described exactly what I have been searching for now for more than two years. �It didn't do it the first summer after the restoration was completed. �After the first summer I removed an engine that was about to self-destruct and installed a second overhauled engine. �At that time I replaced all my aftermarket gears in my transmission and reinstalled all NOS gears. That's when the noise started.
 ï¿½I first thought it sounded like a loose spring clamp rattling. �I believed it well enough that I let it go for quite some time, then I decided I would rule that out and wrapped duck tape around any that were loose. �A test drive told me I didn't find it. �BobW was here and I asked him what he that it was. �He felt it was inside the bell-housing. �A few weeks later Carlsjeep was here and he, like you, thought it was the heat riser. �We wired it tight. �No change. �There is a recently-restored CJ-5 here in town that makes the same noise. �
 ï¿½If you ever figure it out please let me know and Ill do the same for you. �

 ï¿½BobW, now that I've brought this up again here, even after your above suggestion to Tom, don't you feel it's the same noise I had you listen too, only happens between compression and pulling--just floating. I pulled the tranny just this afternoon to replace the synchro blocker rings as I said I was going to do. �I don't see anything in the clutch disk that would cause the noise. Any things else to look at in there while it's open?

 ï¿½Carlsjeep, any new ideas.

 ï¿½Come on guys, we need help solving this mystery. �Thanks.

[Gunslinger]

Without being able to hear it its kind of difficult to guess, but It sounds like what ever it is, its quiet under load, and vibrates when the load drops off.  I've seen that in a couple of different circumstances; the bell housing cover could do it if not allof the bolts were tight; remote.   I've seen a cracked belt pully do that as well, I've also seen a water pump make some weird sounds as well, and sometimes it sounds like its quite, but other noises just overwhelm it and you only hear it when going slow..

Curious issue

[aboyandhisdog]

Calvin, now you have me thinking about the clutch/driveline.  This noise started after I put in one of KW's used engines, so I made the assumption that it must be in the engine or engine-related somehow.  However, now that I think about it , we did the clutch and throwout bearing (and water pump) at the same time.  After everything was buttoned up, I had the noise.  I'm looking at my manual and I see things that could rattle like this:  Throwout lever spring and return spring,  worn flywheel pilot bushing,  "fingers" improperly adjusted???  (Not even sure what this means)  I'm no mechanic and some of this is over my head, but I have to believe we are not the first to be down this road.  SOMEBODY just has to know what we are hearing.  The next time I'm out in the jeep, I plan to see if it goes away when I press in slightly on the clutch pedal, maybe this will help with diagnosis.  I really appreciate your help!

[Carls_jeep]

Ok, have ya'll checked to see if the yokes are in line on each drive line? I hadn't thought about that until it was mentioned here. If you remove the drive shafts one of the spline ends could come off and when you put it back it may be one tooth off or more.

EDIT: what about the old service bulletins, did any of them mention a similar vibration?

[calvinhunt]

Tom,
  As I said a couple of days ago, I now have the transmission out.  I'm looking for anything with my clutch plate or pressure plate (which are not removed) that may be the culprit.  I've even called a couple of people who I believe to be experts but still no great leads.  I think maybe we should bring it up on the CJ-2A page but I haven't registered there.  Not many 3As compared to 2As.  Surely someone has solved this problem in the past.  
  I know our problems are the same, you have identified it exactly as I have experienced it.  If you figure it out I'd be anxious to know what you find and if I figure it out I'll be anxious to share it with you.  I'm glad you are working on it too.
  I'm reinstalling my tranny tomorrow afternoon.  I'll check here just before I do to see if you or anyone else has an idea of something inside the bellhousing that I should check prior to the install.

[F Bill]

I know it is too late for you as ya have the tranny out but when we had this sort of problem often we would set the vehicle up on a lift and run it while poking around underneath to pinpoint the problem. This can be dangerous if you don't have the vehicle supported well, so be really careful if you try it. � The best way to do it would be a drive on platform lift , using jacks to lift the rear axle (or both if it only shows in 4WD) If you have a friendly shop nearby that doesn't mind ole jeeps, it may be worth paying them to do this... �A stethescope and a pry bar help to locate mystery noises. (Harbor Fright has the Stethescope.)

Some possible rattle points....exhaust system, pedals,clutch and brake linkages, shifters, sheet metal panels, loose parts in the toolbox or on the floor, driveshafts (out of phase, bad u joints, loose yokes) parking brake assembly and linkages, throttle linkage, �etc, etc.

On your clutch look for loose springs in the driven disc, or a loose center assembly. The pressure plate could also have loose parts.. Striking the flywheel lightyly with a deadblow hammer may reveal a rattle which you can then track down, if it is in the clutch.

[Carls_jeep]

Tom and Calvin, I just remembered something to look at. Some clutch plates have springs in the center section of them and are to dampen the engagement of the clutch. If the springs break or become loose you could get a rattle there. When I listened to Calvins noise it was more like a rattle than a vibration but when we tied the heat riser open it didn't change.

Look at your clutch plate to check for loose and/or broken springs.

[calvinhunt]

Thanks gents,
 ï¿½I do appreciate your input as to what might be causing the problem. �Even though the noise only occurs when the drive train is not loaded (doesn't happen in either acceleration or deceleration), I am willing to try any and all suggestions. �The noise didn't bother me as much as the challenge to find it now does. �I'm glad that aboyandhisdog is on board with the challenge. �Actually, I'm glad that so many of you have joined in. �
 ï¿½I'm going to go install the tranny but will give the clutch disk and pressure plate another close look first.
 ï¿½Thanks again.
 ï¿½Calvin

[calvinhunt]

I did take that closer look prior to installing the tranny.  I may have found the elusive noise.  Can't be sure at this time but I feel its a good enough lead to cause me to delay the installation of the tranny.  I see that the center of the clutch disk is lose, as it should be to an extent, but not as lose as this one.  It's so lose that it rattles.  I've ordered a new clutch disk.  When it arrives I'll install it, then the transmission.  Then I'll go for a test drive.  I hope to be able to report that the "strange noise" is no longer.  I'll let you know.

[aboyandhisdog]

Thanks, Calvin.  Makes sense - we both had the noise after putting in a new clutch disk.  I will anxiously await your results!  Do you know what the brand of your previous clutch was and the brand of the new one?  Maybe there are some defective clutch plates out there.

[calvinhunt]

Actually, when I did my restoration the clutch disk was one thing I chose to reuse.  It seemed to be in good shape.  That was a mistake.  It seems that the items I decided to let go and reuse during my restoration are the only things that are needing attention as time goes by.  Still anxious to see if this is the cure to my "strange noise".  We'll see.  I have ordered the new disk from Walcks.  I hope it doesn't have the problem right from the start.  Again, we'll see.

[Jesse]

I wish I could record it for you to compare with your noise, but my jeep makes a very strange noise as well. Turns out it is the tool box lid. This sounds way too easy to be your problem, but mine does rattle at various times while driving or sitting still. It sounds bad, bad enough that I though something was wrong until the lid was noticed.

-Jesse

[aboyandhisdog]

Appreciate your input.  But not a problem with mine, nor the tools inside.  This said, the noise IS of the type that it just seems like the fix should be SOOO obvious, and yet...it is very elusive and no doubt internal as suggested previously.  I am anxiously awaiting Calvin's findings upon replacing the clutch disk, but it sounds like it may be a while before he can drive his jeep again to see if that was the problem.