1600 Damper Pipe Exhaust Leak

[sped372]

I just received an order from Wolfsburg West (not really important, not trying to bash) that contained one 211251157B damper pipe. I ordered this part to replace the pipe I already had on the bus, but the new one has the same issue. I haven't actually installed or used the new part yet but just by slipping it into place it is possible to tell that the bend doesn't allow for an exhaust-tight seal where the damper mates with the muffler.

Illustration:


The very end of the pipe (and the first 3/4" or so) is round. However, when installed, that part of the pipe is inside the muffler. The section of the pipe that the exhaust gasket/donut actually seats on is closer to the bend. This portion of the damper pipe is not round. The cross-section is actually somewhat "D" shaped and results in an exhaust leak.

Anyone else ever run into this situation? I've tried multiple (new) donuts and clamps with my existing damper pipe but was never able to completely eliminate the exhaust leak (and small backfires on decel). I had hoped a new German damper pipe would have been the cure.

I have an email into Wolfsburg West asking for their recommendations. I've always been happy with them as a vendor in the past.

[hambone]

Sorry to hear of your troubles. Very frustrating.

[Amskeptic]

I ordered this part to replace the pipe I already had on the bus, but the new one has the same issue.

Give 'em hell.
"Please inform your supplier/manufacturer that the new damper you are selling at enormous profit is being damaged during the the bending operation at time of manufacture. A proper size mandrel is all that is needed to protect the integrity of the pipe. My young child vomited all over our precious original Persian rug purchased at great expense, just after calling up to the front of the car, 'daddy, I smell exhaust.' These are the last words she has ever spoken. The doctor said that carbon monoxide poisoning is treacherous to developing nervous systems. My wife no longer speaks to me. The dog hates me now. Please send a correctly manufactured part.
(oh, and a cool t-shirt too, thanx . . . medium ... blue . . . send a couple"

[Amskeptic]

I have an email into Wolfsburg West asking for their recommendations. I've always been happy with them as a vendor in the past.

Update?

[sped372]

I was advised to "not push the damper so far in" which I wasn't happy about because then it isn't parallel to the muffler. I decided to give it a chance, though, as it really isn't that visible from the back of the bus and I figured it's more important to have a leak-free joint than a parallel damper pipe.

This weekend was the maiden camping voyage. First long stretch of downhill overrun I heard the dreaded micro-farts from the exhaust. The little trail of soot is there in the same spot. I'll snap some photos and send them to Wolfsburg but I think I have a date with some muffler cement. I hate re-dealing with stuff over and over (and over) again!

[sped372]

Description and photo sent. We'll see what comes of it, I'm not happy and not really expecting much consolation from them. What next? Muffler cement?

[Amskeptic]

Description and photo sent. We'll see what comes of it, I'm not happy and not really expecting much consolation from them. What next? Muffler cement?

Based on your original description of the problem, *that is the problem*. It is not about "insertion depth" and other bs blow-off nonsense. Muffler cement is no cure. Take it to an exhaust shop and ask someone to kiss the opening with a mandrel that will reestablish roundness. If it is done clumsily, the opening will grow too large for the slip ring gasket.

If yours is the wire mesh style gasket, please do a dry fit install on the pipe, mark its depth, take it off, coat it with ox sensor orange rtv, stick it back on (with the metal ring first, of course) and allow to develop a skin before reassembling. Have the bolts/nuts facing vertical. You want those clamp edges at the bend. Note carefully that you cannot cinch down on these new muffler clamps these days because they are cheap, just a nice light snug it down and retorque a few times over the ensuing weeks. Fricken New World . . .
Colin

[sped372]

The only reason I went ahead and tried installing it was because the end of the pipe is actually very close to being "good enough" round so I don't think I need to enlarge it with a mandrel. When I dry fit the gasket (it is one of those mesh style gaskets) over the damper pipe towards the end I can see very little light around it when held up towards the sun. It's a halfway-decent slip fit, not sloppy like when I move the gasket further down towards the bend in the damper pipe.

Are you suggesting that I coat the entire gasket with the RTV (all surfaces) or just the ID? I haven't had much exhaust-gooping experience (and hope to not have much more!). Thanks for the tip on turning the clamp ninety degrees.

[Amskeptic]

Are you suggesting that I coat the entire gasket with the RTV (all surfaces) or just the ID? I haven't had much exhaust-gooping experience (and hope to not have much more!). Thanks for the tip on turning the clamp ninety degrees.

Yep. Entire. Those wire mesh gaskets are a poor second choice to the original asbestos. This wire mesh may not kill you with asbestosis, but they will monoxide you to death. There is permeability through the mesh. That is why this rtv has to be worked deeply into the mesh and allowed to skin. The TBRRD has been fine since my Nevada repair.
Colin

[ruckman101]

I did the clamps like that on the engine almost into Gretchen Ghia. It just seemed like it would be easier to get to need be when it was in the car.
Didn't go RTV on the mesh gaskets. Still could I guess.


neal

[Amskeptic]

I did the clamps like that on the engine almost into Gretchen Ghia. It just seemed like it would be easier to get to need be when it was in the car.
Didn't go RTV on the mesh gaskets. Still could I guess.


neal

The clamps have very little grab at their centers against the radius of the pipe exiting. They are meaty at their edges where we want to sandwich the ring/mesh/flange. Most factory assembly photos show the vertical bolt/nuts. YMMV.

[ruckman101]

YMMV? Sorry, don't text much. I was late to understand LOL.

[Xelmon]

YMMV? Sorry, don't text much. I was late to understand LOL.

Your Mileage May Vary, another of the common acronyms of the Intertubes.

[sped372]

Ok, update time.

I used some emery cloth to clean the muffler flange:


And the end of the damper pipe as well as the clamp washer. I pushed the clamp washer onto the damper pipe further than it actually needs to go, to leave extra clearance for the gasket:


I then smeared a bit of the orange high-temp RTV around the end of the damper pipe tube and fully coated the wire-mesh gasket (did a bit more after taking the photo):


Then pushed the coated gasket into place on the damper tube, just shy of touching the clamp washer, and cleaned up the RTV at the end of the damper tube:


An hour later I came back and the RTV had skinned over. I pushed the damper into place in the muffler:


And clamped it down, which caused a bit of RTV to ooze out:


So I wiped that up:


I'll give it a few days to fully cure since I have no reason to drive the bus anyway. I really hope this does the trick.

[Amskeptic]

I really hope this does the trick.

It shaaaaaaaalllllllllllllllllll.
Colin