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Re: [GMCnet] Exhaust problem. [message #355453] Sun, 07 June 2020 01:46 Go to next message
BobDunahugh is currently offline  BobDunahugh   United States
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
Senior Member
Seen this before. Jim K has a point. It seems that for some reason in our GMC's. I've heard an harmonic's from the exhaust. I had a 5 month old, double wall muffler come apart. At the seem that goes the length of that muffler on our 78 Royale. Got the aluminum skin on the bottom so hot. It started a fire in the foam. I then put an aluminum heat shield about 1 inch below that thin aluminum skin. That 1 inch is a MUST. Next. I put in 2 heavy welded steel mufflers in. I'll never have sheet metal mufflers again on anything we own. And while you're under there. Don't forget a gas tank heat shield. I made mine out of some aluminum that I had around. Another couple of my Comfort Zone things..
Bob Dunahugh
78 Royale since 2003

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Re: [GMCnet] Exhaust problem. [message #355464 is a reply to message #355453] Sun, 07 June 2020 12:34 Go to previous message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
Bob,
Great idea to install heat shields, however we seem to get slightly better
rejection of heat from galvsteel.
I’m sure you went with Al to keep wright down .

On Sat, Jun 6, 2020 at 11:46 PM Bob Dunahugh via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Seen this before. Jim K has a point. It seems that for some reason in our
> GMC's. I've heard an harmonic's from the exhaust. I had a 5 month old,
> double wall muffler come apart. At the seem that goes the length of that
> muffler on our 78 Royale. Got the aluminum skin on the bottom so hot. It
> started a fire in the foam. I then put an aluminum heat shield about 1 inch
> below that thin aluminum skin. That 1 inch is a MUST. Next. I put in 2
> heavy welded steel mufflers in. I'll never have sheet metal mufflers again
> on anything we own. And while you're under there. Don't forget a gas tank
> heat shield. I made mine out of some aluminum that I had around. Another
> couple of my Comfort Zone things..
> Bob Dunahugh
> 78 Royale since 2003
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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