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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Tue Jun 22, 2021 7:34 am Post subject: Muffler Backwards |
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On my (new to me) 84 2WD with 1.9, the muffler is installed backwards (there is an arrow indicating flow stamped into it).
It's not overly loud and runs smoothly, but I'm concerned about long-term backflow and curious if it would be quieter installed correctly?
Since it was installed fairly recently, it looks like it will be easy to fix (no rust), but I've never done any exhaust work on these before, so looking for BTDT advice.
Looks like just a matter of removing clamp, both sets of bolts and reversing. Should I be replacing gaskets despite the fact that they are so new, or just assess once I have it apart? |
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9610 Location: Western WA
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Posted: Tue Jun 22, 2021 8:07 am Post subject: Re: Muffler Backwards |
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Yes definitely wanna correct the flow direction.
I’d assume the arrow is meaningful.
Backwards might cause too much back pressure or blow the packing out.
It depends on how the muffler is constructed.
Quiet mufflers will have a required flow direction.
Assess gaskets when you have it apart.
If the old gaskets haven’t fallen apart you can use hi-temp silicone as a sealant.
This is not a critical seal.
But its certainly better to get a good seal at your exhaust connections.
Its better for the operation of the Oxy sensor etc, and prevents jalopiness. _________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16504 Location: Brookeville, MD
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Tue Jun 22, 2021 10:10 am Post subject: Re: Muffler Backwards |
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Sodo wrote: |
But its certainly better to get a good seal at your exhaust connections.
Its better for the operation of the Oxy sensor etc, and prevents jalopiness. |
Thanks, I agree that I want a good seal. But is it true about O2 ops even though it's before the muffler? |
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16504 Location: Brookeville, MD
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Posted: Tue Jun 22, 2021 10:11 am Post subject: Re: Muffler Backwards |
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brickster wrote: |
Sodo wrote: |
But its certainly better to get a good seal at your exhaust connections.
Its better for the operation of the Oxy sensor etc, and prevents jalopiness. |
Thanks, I agree that I want a good seal. But is it true about O2 ops even though it's before the muffler? |
A muffler leak should not affect Ox sensor readings in general. It is usually downstream far enough from the Ox sensor. _________________ Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Tue Jun 22, 2021 1:22 pm Post subject: Re: Muffler Backwards |
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dobryan wrote: |
A muffler leak should not affect Ox sensor readings in general. It is usually downstream far enough from the Ox sensor. |
Thanks for confirming.
Wish me luck; hoping that this job won't follow my typical pattern where it takes at least 1.5 times longer than projected. |
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9610 Location: Western WA
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Posted: Tue Jun 22, 2021 1:41 pm Post subject: Re: Muffler Backwards |
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brickster wrote: |
hoping that this job won't follow my typical pattern where it takes at least 1.5 times longer than projected. |
1.5 times sounds too fast.
Most of us don't work that fast.
Better slow down. _________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Tue Jun 22, 2021 2:04 pm Post subject: Re: Muffler Backwards |
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Sodo wrote: |
brickster wrote: |
hoping that this job won't follow my typical pattern where it takes at least 1.5 times longer than projected. |
1.5 times sounds too fast.
Most of us don't work that fast.
Better slow down. |
I don't think I could be any slower. Good thing I don't make my living this way. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50349
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Posted: Tue Jun 22, 2021 3:15 pm Post subject: Re: Muffler Backwards |
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Hit the fasteners with a quality penetrant at least a few hours before you put a wrench on them, if not a full day. |
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harvgwen Samba Member
Joined: February 11, 2021 Posts: 160 Location: British Columbia, Canada
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Posted: Wed Jun 23, 2021 12:11 pm Post subject: Re: Muffler Backwards |
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I usually figure on 3-4 times the projected time _________________ 1986 Westfalia Vanagon, 2.2 Subaru
British Columbia, Canada |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50349
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Posted: Wed Jun 23, 2021 2:05 pm Post subject: Re: Muffler Backwards |
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harvgwen wrote: |
I usually figure on 3-4 times the projected time |
That still sounds rather conservative. |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Sun Jul 04, 2021 9:55 pm Post subject: Re: Muffler Backwards |
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Following up: I couldn’t reverse the muffler because the tailpipe flange is a different size than the catalytic converter flange. I will try and find one that allows me to run it in the correct direction. |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22668 Location: NYC/Upstate/ROW
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Posted: Mon Jul 05, 2021 3:39 am Post subject: Re: Muffler Backwards |
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Or just drive it reverse? _________________ .ssS! |
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Red Ryder Samba Member
Joined: June 26, 2021 Posts: 951 Location: Northern California
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Posted: Mon Jul 05, 2021 8:36 am Post subject: Re: Muffler Backwards |
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[quote="brickster"]
dobryan wrote: |
Wish me luck; hoping that this job won't follow my typical pattern where it takes at least 1.5 times longer than projected. |
Repair times vary. Most of us who work on these old vans don’t wear a wristwatch… _________________ “Most everyone’s mad here. You may have noticed I am not quite all there myself.” — Cheshire Cat, Adventures of Alice in Wonderland
“Scarlett” — 1990 Vanagon Carat Wolfsburg Edition
Tornado Red |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Fri Jan 05, 2024 3:14 pm Post subject: Re: Muffler Backwards |
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Let's do the time warp again...
Thanks to everyone who already responded. I've still got this on my always growing list of small stuff. When I disconnected the muffler and tail pipe, the muffler holes didn't match up on either side. I had a trip coming up, so I put it back as-is.
Is there a standard hole spacing, etc. for these, or am I dealing with an aftermarket variance? I wonder if I rotated the converter 180 relative to the header if things would line up?
Just wanted to tap into the group mind before I start taking things apart again.
This is on a stock 1.9 Federal setup.
(FYI: this photo is purposefully flipped to make the markings easier to read)
Last edited by brickster on Fri Jan 05, 2024 5:17 pm; edited 1 time in total |
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ALIKA T3 Samba Member
Joined: July 30, 2009 Posts: 6357 Location: Honolulu,Hawaii and France
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4790 Location: Bemidji, MN
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Posted: Fri Jan 05, 2024 4:31 pm Post subject: Re: Muffler Backwards |
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mufflers ARE directional but sometimes it doesn't matter. the MagnaFlow one i have is straight through BUT it has perforations into the outer canister that are angled to 'catch' exhaust flow. if it was installed backwards, it would simply be louder.
very few modern mufflers are "glass packed" with fiberglass so it won't ruin that but much care is taken in a modern baffled muffler to ensure maximum flow with minimum resistance and noise. this typically includes cuts into expansion chambers that are scooped into the exhaust flow.
bottom line: reverse it to the proper direction. it's just nuts and bolts. snap 'em off and use new ones. _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50349
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Posted: Fri Jan 05, 2024 4:55 pm Post subject: Re: Muffler Backwards |
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If you have the bolts in, as per the pictures, just tighten them down and see if you get a seal. If you have no leaks you should be fine for years until some other exhaust part needs replacement.
Looks like your bolts might be a good candidate for using acorn nuts. Buy a few SS washers as well to shim the nut out a bit if it bottoms out on the bolt and doesn't apply enough pressure to the joint. |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Fri Jan 05, 2024 5:20 pm Post subject: Re: Muffler Backwards |
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ALIKA T3 wrote: |
I'm surprised to see reinforcements for the tail pipe end if it's mounted backwards then.
Do you have pics of the current tail pipe? |
Are you referring to the 'legs' between the flange surface and muffler's crimped end? If so, they're found on both sides (added a snap of the tail pipe connection to the end of my last post). |
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brickster Samba Member
Joined: January 05, 2004 Posts: 512 Location: CO, USA
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Posted: Fri Jan 05, 2024 5:22 pm Post subject: Re: Muffler Backwards |
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DanHoug wrote: |
bottom line: reverse it to the proper direction. |
I did try to reverse (see my first post from today). I'll likely take it apart again and look at things with new eyes and brain. |
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