Loose exhaust at the Manifolds..GM design flaw?

[FrontRangeRVer]

In anticipation for receiving my new stainless steel exhuast tips yesterday, I took my motorhome down to "The Springs" (Colorado Springs) to a good muffler shop to get the rear tail pipes raised as they were both angled down about 8" below the compartement doors, and the rear hangers are wayyyy too long.

The muffler shop told me that BOTH pipes were loose at the manifold and that is a GM design flaw. You could grab the tailpipes and move them up and down, causing the WHOLE exhaust pipe to move (almost freely) at the manifolds. They were going to "fix" this, but since neither exhaust leaked at the manifold, I chose to just re-hang the rear tail pipes higher and let the "looseness" of the pipes at the manifold go unchanged.

Wonder if anyone else has heard of this....

[FrontRangeRVer]

In anticipation for receiving my new stainless steel exhuast tips yesterday, I took my motorhome down to "The Springs" (Colorado Springs) to a good muffler shop to get the rear tail pipes raised as they were both angled down about 8" below the compartement doors, and the rear hangers are wayyyy too long.

The muffler shop told me that BOTH pipes were loose at the manifold and that is a GM design flaw. You could grab the tailpipes and move them up and down, causing the WHOLE exhaust pipe to move (almost freely) at the manifolds. They were going to "fix" this, but since neither exhaust leaked at the manifold, I chose to just re-hang the rear tail pipes higher and let the "looseness" of the pipes at the manifold go unchanged.

Wonder if anyone else has heard of this....

[RV 4 2]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Wonder if anyone else has heard of this.... </div></BLOCKQUOTE>

No, that is kind of wierd. You would think that if this was a larger issue, it would be all over the RV forums.

[FrontRangeRVer]

I'm kinda thinking that the looseness of the exhaust into the manifold is deemed as "normal" under GM engineering..... with no exhaust leaks.

Im wondering if ALL the Workhorse exhaust are loose at the manifolds????

[M&EM]

I don't know if mine were loose from the factory.
But after the "Cat" recall several years ago where all or most all of each sides exhaust components were replaced, I did notice looseness at the manifold to exhaust pipe joint, whereby the entire system on each side could be rotated. The servicing dealer stated this was normal. As long as there was no sign of leakage it was to be left alone.

I haven't had any exhaust leak indications since then. (3 years ago). I believe the joint gets tighter at operating temperature.

Marty

[BEBOP]

I noticed the other day that mine were loose and would rotate some.
I have to get someone to do the rotating so I can get under and lookie C.
bebop

[Bob (WA0MQE)]

FrontRangeRVer...

I had the same problem with my previous motorhome which also had the 8.1 big block. The donut exhaust manifold to tailpipe gasket was the problem. The left one was the only one that was loose, but I ordered two gaskets and replaced them myself in less then an hour.

I ordered them from Transwest Truck Parts in Denver (had them in stock) 800-289-3161. They shipped via mail and I had them in two or three days.

[JB Driver]

This past August I have a similiar situation in Washington state. The donuts at the manifold and exhaust system were loose. It caused more air into the system which was telling the O2 sensor that I was running a lean situation in the engine and the TCM or one of the other control modules reacted by increasing the flow of more gas into the system which caused a super heat situation which caused the right catalytic converter to fail. According to the techs that worked on the coach the loose donuts caused the problem. The result was both catalytic converters had to be replaced along with both the exhaust pipe header gaskets (donuts). It was a very costly repair. The good news was that it was all covered by factory warranty by Workhorse Custon Chassis.

[FrontRangeRVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M&EM:
I did notice looseness at the manifold to exhaust pipe joint, whereby the entire system on each side could be rotated. The servicing dealer stated this was normal. As long as there was no sign of leakage it was to be left alone.

I haven't had any exhaust leak indications since then. (3 years ago). I believe the joint gets tighter at operating temperature.

Marty </div></BLOCKQUOTE>

Sounds EXACTLY like mine!! I am thinking that ALL the Workhorse chassis' exhaust pipes are loose and can be rotated somewhat....at least I am HOPING that's normal!!

[rgrstndgby]

JB, I can't tell how old your MoHo is, or what it is, but did WH correct your problem under their standard warranty, or under some "emission extension"?...rgr..

[DriVer]

The way this was presented to me was that the entire exhaust system is mounted in large rubber hangers. This is to allow for vibration and the natural flexing that will occur when the motorhome moves down the road or through and across some obstructions. The exhaust system as a whole is both long and very heavy.

Would it not make more sense to allow the exhaust system to flex a bit when the engine torques up "OR" would it be more the understanding that the exhaust pipes should be bolted rigidly to the manifolds?

I would submit that the point of attachment between the manifolds and pipes should be allowed to "give" slightly so that when the engine torques up it wouldn't have the tendency to break the bolts attaching the pipes to the manifold.

My pipes do move and I do not have any exhaust leakage that I am readily aware of. Whether or not it can be seen as a deficiency in engineering or a purposefully considered implementation of how these components should be attached I believe that the way the pipes are is the way it should be.

That said if you have a leak then that would have to be evaluated and resolved.

[JB Driver]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">JB, I can't tell how old your MoHo is, or what it is, but did WH correct your problem under their standard warranty, or under some "emission extension"?...rgr.. </div></BLOCKQUOTE>

RGR - Replying to your inquiry. The coach is a 2004 National RV - SeaBreeze LX. The chassis is a W-22 with the 8.1 GM 8.1 powerplant. At the time of the incident I had 32,540.4 miles on the coach. The repair was covered under the Five year/70,000 mile emission system warranty. The repairs were completed by Eric's RV Performance Center, a Workhorse authorized service center, in Sequim, Washington. The towing to the service center was covered under CoachNet Roadside Service. The repair took seven days to complete due to waiting for authorization from Workhorse and the delivery of parts.

[FrontRangeRVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DriVer:

My pipes do move and I do not have any exhaust leakage that I am readily aware of. Whether or not it can be seen as a deficiency in engineering or a purposefully considered implementation of how these components should be attached I believe that the way the pipes are is the way it should be.

That said if you have a leak then that would have to be evaluated and resolved. </div></BLOCKQUOTE>

My thoughts exactly when the muffler shop said it was an engineering design flaw. I knew that I had no exhaust leaks, and it seemed to me that there should be SOME flexability, so I did NOT have them do any work on the looseness. They said that GM used to use springs for the donut connection, but discontinued that several years ago.

Just FYI, I can turn both complete pipes about 1/2 inch each way at the donut in their hangers, and I repeat that I don't have any exhuast leaks.

[NeilV]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DriVer:

My pipes do move and I do not have any exhaust leakage that I am readily aware of. Whether or not it can be seen as a deficiency in engineering or a purposefully considered implementation of how these components should be attached I believe that the way the pipes are is the way it should be.

That said if you have a leak then that would have to be evaluated and resolved. </div></BLOCKQUOTE>

My thoughts exactly when the muffler shop said it was an engineering design flaw. I knew that I had no exhaust leaks, and it seemed to me that there should be SOME flexability, so I did NOT have them do any work on the looseness. They said that GM used to use springs for the donut connection, but discontinued that several years ago.

Just FYI, I can turn both complete pipes about 1/2 inch each way at the donut in their hangers, and I repeat that I don't have any exhuast leaks. </div></BLOCKQUOTE>

Imagine all the noise and potential for fatigued or broken exhaust parts if that was not so. The engine mounts would have to be less resilient to keep it from torqueing so much when accelerating and decelerating and the hangers would all have to be more solid to keep movement of the pipes down to a minimum which would make things so much noisier inside.

On one car we had a mechanic put an extra hanger on after doing some exhaust work to make the system better than factory as in his opinion it flexed too much. The noise inside was so great that the radio did not have sufficient volume to overcome it. It was lounder than if we had put straight through mufflers and exited them under the floorboards. His unrequested modification was quickly removed.