Problem with Genuine Porsche 911 muffler

88911cs · 11-15-2014, 06:02 AM

Hi Guys ,
I'd like to run this by you and see if anyone has any ideas beyond what I've surmised . I have a 88 911 with under 15,000 original miles and have owned the car since new . Shortly after buying it I installed a Borla muffler and its been on it ever since . The car has always been a little louder than I would like , but I guess as I've gotten older it bothers me more so I decided to revert to a stock muffler and ordered one through my Porsche dealer . I should add that I've always had a cat bypass on the car and decided to upgrade to a stainless M+K version to replace the mild steel one at the same time I do the muffler . After installing the muffler and new bypass ( sound was nice - a little louder than stock - just what I wanted ) I took it for a ride and noticed a strong rubbery plastic smell coming through the heating system . I had cleaned all the stickers from the outside of the muffler so didn't expect much in the way of smell beyond the first time heat cycle smells you always get with new exhaust parts . After about 6-7 miles the car started to stutter and loose power and I wondered if I'd make it back to my shop . I stopped at home and did a quick check around with nothing obviously wrong with a cursory check . After a half hour I drove back to my shop and barely made it back . I checked the muffler over before installation for any plastic plugs ( there were none ) and should add that the muffler was handed to me without any packaging at the dealer . I thought it through and surmised that either the muffler had something plastic lodged from view inside or perhaps packing peanuts . After letting the car cool down I re-installed the Borla muffler and took it out for a ride - everything was fine . Has anyone ever heard of something like this happening ? The dealer has ordered another muffler which I'll see next week . Thanks for the input in advance .

Targa Me · Targa Me's Garage

I've never heard of anything like that.
By re-installing the Borla you seem to have isolated the problem.

Re-install the second new stock muffler and report back.

Jrboulder · 11-15-2014, 06:15 AM

My genuine Porsche muffler built 10/84 had a little smell to it that certainly went away after the first short drive. See how the new one works and report back.

McLaren-TAG · McLaren-TAG's Garage

That's weird, but you've isolated the offending part. IMO though, I'd tell the dealer to keep their stinkin' muffler and buy one from the forum. 3.2 1 in 1 out mufflers are a dime a dozen and ta tenth of what the dealer charged you.

15,000 original miles on an 88!?!?

theiceman · 11-15-2014, 06:50 AM

yeah im stil trying to get past the original owner 88 with less than 15k

pics ?

88911cs · 11-17-2014, 07:01 AM

Hi Guys ,
Thanks for the responses . I've never had so much as a hiccup with the car over the years so this was pretty bizarre . I had to return the muffler to the dealer this morning with a replacement due in later this week . Nobody I've spoken to could offer any explanation beyond the idea of some foreign material lodged in the muffler . I took the car out Saturday and put about 30 miles on it with the old Borla and no issues . As soon as I get the replacement muffler installed I'll update the thread .
Regards,
Bryan

DRACO A5OG · DRACO A5OG's Garage

Yeah, some lodged inside, and choked out your baby lien to a clogged cat. Lucky you made it back.

Maybe next time blow some compressed air in both holes to insure they did not do it again???

88911cs · 11-17-2014, 07:43 AM

Definitely going to blow air in it for sure . I tried that after removing the muffler but more over than likely whatever was in there melted . The smell was very similar to burning tires - very strong and pungent .

Porchdog · 08:37 AM

I work at a shop where we fabricate a lot of stainless steel. Polished stainless comes with a plastic film on it to protect the finish.

Sometimes fabricators forget to remove the film. I would bet that happened to your muffler - the plastic was left on the inside surface of the outer shell and came off when it got hot.

I worked on a job at a pharmacuetical company where a large (6' x 6' x 24' inside),new steam sterilizer had this happen with the stainless lining. The first time they heated it up all the plastic melted all over steam coils, cooling coils, the inside of the panels, fans. It was a huge job cleaning it up.

We didn't fabricate or install the unit so we had no liability - but we got the job to clean it up. I was amazed that it got shipped and installed without anyone noticing and removing the plastic. I have to assume it was just a "not my job". attitude.

ClickClickBoom · ClickClickBoom's Garage

My bet is its material from plugging any and all openings for "backgassing". Stainless needs the HAZ (heat affected) protected with shielding gas for proper welding. When you get the new muffler affix a shop vacuum cleaner outlet to the inlet to insure free flow(after checking for possible visible blockages).

GH85Carrera · GH85Carrera's Garage

Many years ago I stored the OEM muffler for my 914. When I went to re-install it the car ran horrible for a few minutes then a cooked mouse blew out the exhaust tip. The nesting material blew out for a few miles and all was fine for many long years.

It sounds like you have some sort of obstruction in there. Can you borrow a borescope?

88911cs · 11-17-2014, 10:13 AM

Hi Guys ,
Wow - there are some horrible scenarios . I wish I could have gotten my hands on a boroscope before returning it . I didn't see any smoke trailing me while driving . I have wondered how this smell was pouring out of the heating system - even with a blockage in the muffler how does it end up in the heating ducts ? I drove around Saturday with the heat blasting and it was fine , but I did notice a faint wiff of the smell outside the car when I parked it in the shop . I just hope this doesn't turn out to be a ''batch'' problem where the replacement has the same issue . I've restored cars for almost 30 years and I can't tell you how many times a defective part would get replaced with one with the same problem .

evan9eleven · evan9eleven's Garage

Quote:

Originally Posted by Porchdog

I work at a shop where we fabricate a lot of stainless steel. Polished stainless comes with a plastic film on it to protect the finish.

Sometimes fabricators forget to remove the film. I would bet that happened to your muffler - the plastic was left on the inside surface of the outer shell and came off when it got hot.

^this

I own a brewery and a restaurant and obviously deal with gobs of stainless. Its amazing how many fabricators don't bother to remove the plastic film before riviting trim on top of another piece of material. So this is a plausable explanation. Hope the next muffler isn't a Friday afternoon build!

88911cs · 11-19-2014, 12:51 PM

Hey Guys ,
New muffler came in to the dealer today and I ran right down to pick it up . First thing I notice is there isn't a mark on it - no scratches , no dings , no outlet out of round - all good signs . I put my air hose to both ends ( blew from the outlet side first ) and the air was coming out much stronger than the one I took off the car . Did the install and went for a ride - no smells , perfect performance . What a relief . I'm wondering now if that other muffler had already been installed and returned before I got it with all the miscellaneous dings , scratches etc. it had . A little bit of a headache and quite a scare initially , but it all worked out . Thanks for all your comments - it was great to have positive reinforcement .
Regards,
Bryan