Deleted my rear muffler...

indestruktable · #1 02-26-2012, 04:00 PM

At some point in my 740td's history, a Bosal muffler was installed on the back of the car. I'm pretty sure this is a muffler for a gasoline car; it's quite restrictive. Last week, the spout on the back of the muffler- which was quite rusty to begin with- fell off. So I cut the exhaust pipe just before the muffler and welded a straight pipe to the back of the car.

[ATTACH=CONFIG]334[/ATTACH][ATTACH=CONFIG]335[/ATTACH]

This only took a few minutes and I'm really happy with the results. The center muffler is still there, so the noise is really no higher than it was before at idle or at cruising RPM's. But around 2500rpm, it has a much deeper, more throaty sound.
In addition, it seems like there's less backpressure on the engine- I can coast so much farther now.

I also fixed a leaky vent line on the fuel filler which was causing diesel to spill in large quantities every time I filled up. And I replaced the heat shield on the #1 injector, which was leaking pretty badly as it was only finger-tight!

Despite having all of these issues, I averaged 25.4 mpg on B10 with city traffic and a heavy foot. I can't wait to fill up again because I can only imagine it improving with these repairs...

anders · #2 02-27-2012, 08:10 AM

I did the same with my 240, they sound good with one muffler.

indestruktable · #3 02-28-2012, 07:29 PM

And apparently it does more than sound good! I filled up today- 29.8mpg, and that's city mileage with an auto trans and leaky return lines. Impressive.

michaelovitch · #4 03-03-2012, 12:18 PM

Need a sound teaser asap !

I'm looking for a "sporty" muffler but if it works good without.....

ian2000t · #5 03-03-2012, 01:31 PM

That's what I did with mine aswell. Just took rear box off and replaced with straight 2 and 1/4" pipe, slash cut. Bit more burble at idle and quite a nice but reasonable exhaust note. Been thinking I need to get a video of it soon....

RedArrow · #6 08-18-2019, 07:54 PM

Video?

I thought of getting off or replacing the mufflers.
I think they are rusted and clogged

RedArrow · #7 08-18-2019, 08:59 PM

Quote:

Originally Posted by ian2000t

That's what I did with mine aswell. Just took rear box off and replaced with straight 2 and 1/4" pipe, slash cut. Bit more burble at idle and quite a nice but reasonable exhaust note. Been thinking I need to get a video of it soon....

It sounds good but out of the 2 mufflers we have, isnt it the first one that gets clogged first? Isnt it the first one that gets the most heat too? If i have exhaust related or muffler related restrictions then i tjink it is the first muffler tgat needs to go (or get replaced) first. I might be wrong. Ideas?

I prefer stock sounds but also prefer no restrictions due to wrong "new" setup or a clogged rustbucket old muffler with second muffler cut off. I just need to get the closest one to stock possible. Currently i have two mufflers on the car. The entire piping is very rusty btw too.
Link me to the mufflers pls!

v8volvo · #8 08-22-2019, 04:43 PM

For what it's worth, my wagon has had the front muffler (resonator) replaced with a straight section of pipe. It was done prior to my ownership and has been this way since I have had it. No noticeable difference in noise level versus a full stock exhaust system, maybe a tiny bit more growl audible if you are standing outside the rear of the car, but not enough to hear it from inside even if you have the windows down. The stock rear muffler is still in place. It seems like that is the one that does most of the noise suppression. Removing the rear muffler does make the exhaust much louder.

I don't know why it was done on my car, could have been for a restriction concern but the front muffler seems to be the one that rusts out first also, water vapor in the exhaust may be more likely to condense there.

Bottom line, if you are considering removing the front muffler and want to keep stock exhaust noise level you can probably do it. You could also replace it with a straight through (glasspack type) muffler if you want to eliminate the restriction but keep something that contributes to noise reduction in that location.