(Engine experts needed) Chirp, Vibe, Pop (What is Wrong?)

[Juggernaut]

The things I do for my country. A V8 is just about as American as, well, it's actually the most American thing I can think of.

If I can find the issue, the inline 6 will be staying a while longer while I figure out the swap. If I can't stop it from chirping I have trust issues with driving further at this point.

You sir are a true patriot!

 

[toximus]

You sir are a true patriot!

I will humbly accept the metal of honor via the mail due to Corona virus and because I'm busy taking care of my jeep, er I mean, America.

 

[toximus]

Going back to making the 4.0 work...

1.) make it shudder then lightly ride the brake at the same time. The EMCC is supposed to disengage when the brake is applied. If the vibration/shuddering stops when the brake is applied, its the converter clutch.

I was trying this last night. I don't have any big hills close enough make it shudder but I did try braking while it was chirping. I found that either of these 3 things would happen:

1) The transmission would get out of OD, the engine would rev gently, and the chirp would stop. Or
2) The transmission would get out of OD, the engine would rev hard, and the chirp would continue. Or
3) The transmission would stay in OD, the engine would raise RPMs gently to compensate for the load and the chirps would continue.

I also found that the chirp (not a squeal) will happen under initial application of hard acceleration (normally 2-4 chirps can be heard before they'd stop) whether putting my foot down at 15mph, 45mph, or 60mph the chirps happen at high RPMs as the Jeep accelerates. and it doesn't change tone or frequency based on RPM. Meaning it sounds the same if it's chirping at 2k rpm at 50mph (like in the video I posted in the first post) or if I'm putting my foot down at 60mph and turning the engine at 4k rpm. While playing around doing this is when the belt shredded — not on a hill, just flat road at around 55mph.

I untangled the belt bits and shook all of the pulleys while the belt was off. Everything is solid including the SC bracket doesn't wiggle. The one composite pulley does have the slightest movement, I have a replacement on the way, but I'm starting to think that it's within a normal tolerance.

I counted the ribs of each pulley and they each have 6 (as they should).

Doing the some testing in the driveway, with the brake held and trans in drive and revving the engine the belt gives more slack than the auto tensioner can take up. All of the high load accessories such as power steering and SC are on one side of the crank and the other side only has the alternator and the belt slack all gets thrown to that one side. The belt flops around to the point of hitting the water pump and crashing into itself where the belt double backs. This seems to happen more when blipping the throttle. It would seem that it'd be easy for the belt to jump off a few ribs which is probably why it happened when I was doing those hard accelerations.

I understand that under normal driving conditions that I won't be slamming on the gas and doing stupid stuff, but whatever the chirping, vibing, popping things is does happen during normal driving conditions. So I don't think I'm too far off base recreating it by using these methods.

 

[toximus]

the belt gives more slack than the auto tensioner can take up.

When installing the belt the tensioner is at it's absolute tightest and is difficult to get the belt on. There is no possible way that I can install a smaller belt.

I have also tried adjusting the movable idlers on the BoostedTech bracket to give the belt more slack but that doesn't change anything (not better or worse).

 

[toximus]

I cleared the code and will check for it again after every drive.

I checked for codes during my 50 mile drive last night and no codes came up.

 

[Juggernaut]

Going back to making the 4.0 work...



I was trying this last night. I don't have any big hills close enough make it shudder but I did try braking while it was chirping. I found that either of these 3 things would happen:

1) The transmission would get out of OD, the engine would rev gently, and the chirp would stop. Or
2) The transmission would get out of OD, the engine would rev hard, and the chirp would continue. Or
3) The transmission would stay in OD, the engine would raise RPMs gently to compensate for the load and the chirps would continue.

Interesting. Not the results I was going for. The application of the brake should have signaled the lockup clutch to disengage and it should have stopped the shuddering/vibration. You would also have seen a slight/couple hundred rpm rise when it disengages. Not as much rpm as a full 4-3 downshift but more of a half shift worth if that makes sense. Anyway I think your on to something now with the belt /tension. Leave the tranny surgery for plan B or maybe Z.

 

[BuildBreakRepeat]

Can you add a belt tensioner on the slack side?

 

[toximus]

Can you add a belt tensioner on the slack side?

I talked to @mrblaine about that and he said that it's not needed and there's not really room for it. His theory is that there's something simple that's wrong because BoostedTech has too many of these kits out there for the kit design to be the issue. I've also heard from other people that say they have had the kit installed without issues.

I've looked stuck my head under the hood for a few hours this morning with the engine not running, running, and revved and couldn't find anything that is wrong aside from the belt slapping around.

After work I'm going to barrow a GoPro and remove the hood and go thrash this belt to see what I can find.

I understand how the belt could chirp; but I am not sure how the belt could cause the vibration/shudder? One thing at a time I guess.

 

[toximus]

Here's the routing from the instructions:

 

[toximus]

I was able to take video of the belt when it chirped, and popped. Details and video to come.

 

[toximus]

Here's what happened...

I was accelerating in OD. The chirp started and progressed through the stages of chirping I previously described in the original post (where it changes in tone and frequency). I kept it in OD until I heard the pop.

The pop sounded like it came from the transmission area or rearward and metallic like a thin gauge skid plate fell off and hit the road with a hollow "clunk" sound. Mrs Tox and I lurched forward in our seats. A bad mechanical smell wafted into the Jeep and could be smelled outside the Jeep around the rear but quickly cleared. I couldn't smell anything around the engine bay or belt. I couldn't find anything that fell off on the road.

The video is super interesting. I apologize for the large file size but I did want to make sure it is high resolution enough and good audio quality. Download video 138MB

The chirp starts at 0:03, vibrating at 0:53, and pop at 0:55. Slowmotion reply at 1:20.

Watch the automatic tensioner hammer as the belt whips and the suspension move down when it pops.

I still have another 45 minutes of video to watch but so far I don't see anything weird happening aside from the floppy belt. I don't see anything that looks like it's causing the belt to have issues in the engine bay.

Is it possible that the transmission is the issue doing this and is causing the shudder to be seen in the belt as it pulses from the transmission through to the belt?

 

[toximus]

Watch the washer fluid and how it reacts too! If this wasn't my Jeep I'd think it was cool.

 

[BuildBreakRepeat]

View attachment 160951

Here's what happened...

I was accelerating in OD. The chirp started and progressed through the stages of chirping I previously described in the original post (where it changes in tone and frequency). I kept it in OD until I heard the pop.

The pop sounded like it came from the transmission area or rearward and metallic like a thin gauge skid plate fell off and hit the road with a hollow "clunk" sound. Mrs Tox and I lurched forward in our seats. A bad mechanical smell wafted into the Jeep and could be smelled outside the Jeep around the rear but quickly cleared. I couldn't smell anything around the engine bay or belt. I couldn't find anything that fell off on the road.

The video is super interesting. I apologize for the large file size but I did want to make sure it is high resolution enough and good audio quality. Download video 138MB

The chirp starts at 0:03, vibrating at 0:53, and pop at 0:55. Slowmotion reply at 1:20.

Watch the automatic tensioner hammer as the belt whips and the suspension move down when it pops.

I still have another 45 minutes of video to watch but so far I don't see anything weird happening aside from the floppy belt. I don't see anything that looks like it's causing the belt to have issues in the engine bay.

Is it possible that the transmission is the issue doing this and is causing the shudder to be seen in the belt as it pulses from the transmission through to the belt?

Is that your belts hitting in the picture?? I’ll take a look at the video.

 

[toximus]

Is that your belts hitting in the picture?? I’ll take a look at the video.

Yes.

 

[Rick Flair]

I’m gonna stand on transmission. You might have something else there too, but hard to say.

 

[toximus]

While we're checking off options, I've replaced my steering pump and nothing changed.

 

[Daryl]

Didn’t you recently repair a leak in your transmission? Maybe the hairline crack has grown into an internal oil passage.

 

[toximus]

Didn’t you recently repair a leak in your transmission? Maybe the hairline crack has grown into an internal oil passage.

I did. https://wranglertjforum.com/threads/42rle-crack-or-leaky-seal.34313/

It's also possible that the transmission previously leaked to the point of running low on fluids. Not since the rebuild, but before. I have no way of knowing if the leak would have stopped under a certain level. However I can say that I've never thought I had transmission trouble.

 

[toximus]

I'm seeing no indication of it, but if say the only thing going on was a pulley moved around changing belt tension. Would that be violently felt inside the Jeep and seen as suspension movement after it "pops"?

 

[Apparition]

View attachment 160951

Here's what happened...

I was accelerating in OD. The chirp started and progressed through the stages of chirping I previously described in the original post (where it changes in tone and frequency). I kept it in OD until I heard the pop.

The pop sounded like it came from the transmission area or rearward and metallic like a thin gauge skid plate fell off and hit the road with a hollow "clunk" sound. Mrs Tox and I lurched forward in our seats. A bad mechanical smell wafted into the Jeep and could be smelled outside the Jeep around the rear but quickly cleared. I couldn't smell anything around the engine bay or belt. I couldn't find anything that fell off on the road.

The video is super interesting. I apologize for the large file size but I did want to make sure it is high resolution enough and good audio quality. Download video 138MB

The chirp starts at 0:03, vibrating at 0:53, and pop at 0:55. Slowmotion reply at 1:20.

Watch the automatic tensioner hammer as the belt whips and the suspension move down when it pops.

I still have another 45 minutes of video to watch but so far I don't see anything weird happening aside from the floppy belt. I don't see anything that looks like it's causing the belt to have issues in the engine bay.

Is it possible that the transmission is the issue doing this and is causing the shudder to be seen in the belt as it pulses from the transmission through to the belt?

It’d be interesting to see a tach overlay to see if it had a simultaneous blip.