Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-24-2004, 07:47 PM
300SDog's Avatar
gimme a low-tech 240D
 
Join Date: Jan 2003
Location: central ky
Posts: 3,602
Does a '79 240D need a rear muffler??

The pipe on mine rusted through about 2" north of the muffler and finally the rear muffler cannisiter fell off.

I've been driving the car nearly a week now with NO rear muffler and it's not bad with no excessive noise or fumes in the car.

Right now I'm thinking about a straight pipe custom fitted to extend the break to reach back to the bumper.

Has anybody skipped the rear muffer entirely on a 240D??

This seems like a good idea to me, same as bypassing the central locking system at the firewall, ripping out the crummy cruise control and hurling plastic trunk panels that trap water underneath them into the garbage.

Reply With Quote
  #2  
Old 11-24-2004, 08:47 PM
Registered User
 
Join Date: Jul 2000
Location: Exeter, NH
Posts: 139
I had a straight rear pipe on my 240 for its last 50k miles or so, and other then a little pit of a drone it ran fine. No noticable power change good or bad.
__________________
82 Rabbit diesel (first d), 84 Jetta turbo d (300k when sold), 83 240d (305k when sold), 84 F250 6.9d w/Banks turbo(parts truck), 86 F250 6 cyl.gasser(waiting for 6.9d), 84 300d ( 347k Sold 8/04), Y2k New Bettle TDI (185k miles), 95 740IL (wifes), 87 300TD (206k Sold 7/05), 05 Passat TDI Wagon
Reply With Quote
  #3  
Old 11-24-2004, 09:01 PM
84300DT's Avatar
Senior Member
 
Join Date: Jan 2002
Location: Mass.
Posts: 2,219
from a turbo point of view i also ran mine without a rear muffler for about a month with no problems. i got an ansa put on after that but frankly there was no difference in sound/performance.
__________________
1984 300D Turbo - 231k....totalled 11/30/07 RIP
Reply With Quote
  #4  
Old 11-26-2004, 11:47 PM
300SDog's Avatar
gimme a low-tech 240D
 
Join Date: Jan 2003
Location: central ky
Posts: 3,602
Thank you for the replies. Here's today's report from the muffler shop........

Bad news is the resonator pipe halfway down has rusted through just above the resonator. Am hoping it will make it through the Winter.

Muffler guy said bypassing the resonator and replacing the muffler makes more sense than skipping the muff and keeping the resonator. The muffler provides back pressure, he said.

And apparently heavy guage ALUMINUM pipe is the way to go. For $195 I can replace the extire existing system with straight aluminum pipe from the front pipe running all the way back and including a new rear muffler.

Does anybody have any experience with Aluminum pipe for the muffler system? It sounds pretty good to me, rust free forever.
Reply With Quote
  #5  
Old 11-27-2004, 09:35 AM
Registered User
 
Join Date: Sep 2004
Location: Canada
Posts: 495
Tractor Mufflers

I've seen various sizes and shapes of galvanized tractor mufflers available at Princess Auto. There is not a lot to them- pretty much just an expansion pipe with a single baffle- very light weight, inexpensive, and easy to accomodate. I've taken my previous cars (VW's) to a muffler shop where they actually prefer to do creative pipe bending as opposed to insisting on selling OEM, and when the time comes, I'm going to get them to custom install one of the tractor mufflers on my 300D.

I agree it would be better to omit the resonator if it has crapped out also, but no sense in scrapping it if it's still good.

Dave
Reply With Quote
  #6  
Old 11-27-2004, 01:35 PM
angst's Avatar
Registered User
 
Join Date: Feb 2002
Location: Chattanooga TN
Posts: 272
On a 79 300sd I replaced the final muffler with straight pipe with no discernable increase in noise. I drove it for a short while with nothing but a couple feet of pipe behind the pre muffler and you could tell the volume then probably because the exhaust vibrations were under the car. This noise increase was very slight though.
If you went so far as to replace everything with a straight back pipe I doubt the noise would be any louder than the engine. I am not an expert but I also would doubt that this would lower your backpressure to the point of causing problems. If the work has to be done anyway why not take the opportunity to have fun "hot roddin" your 240D with a "performance exhaust" and put at most a gutless muffler at the end.
Reply With Quote
  #7  
Old 11-28-2004, 01:44 AM
300SDog's Avatar
gimme a low-tech 240D
 
Join Date: Jan 2003
Location: central ky
Posts: 3,602
Angst and Coldwar: I asked the muffler guy about running a straight pipe from stem to stern, knowing that heavy trucks often get away with straight pipe rigs.

His answer was that truck engines operate under heavier load, so they dont need as much back pressure in the system as does the 240 engine that free wheels without resistance alot of the time.

Now it's been about a week since the muffler fell off, unloading exhaust just behind the axle where the break occurred. And suddenly the back trunk panel has blackened with soot as it never has before. So it strikes me that back pressure provides more complete combustion too. Also fuel mileage has been crummy since the muffler fell off.

Meanwhile, rust-worthy OEM steel muffler and resonator systems look like sucker items to me at $350+ in parts alone. For that kind of money I want a 5-spd gearbox from a later model junkyard Benz that can be force fitted, souping up the top end of the existing 4-spd that now begs for an overdrive at 80-85mph on highway runs.

Hell yes, running heavy guage aluminum straight pipe to a custom cobbled cannister rig in the back makes sense to me. A cheap tractor muffler sounds like a good idea, but I'll let the muffler tech decide what kinda muff provides the best back pressure, improving combustion and lessening fuel consumption.

I guess the resonator halfway down acts like a tuned expansion chamber that helps to regulate exhaust flow. According to the shop, the resonator plays secondary role to the cannister muff at providing back pressure. Chief concern of the muffler tech is fitting the aluminum pipe to the steel front pipe that connects with the manifold.

With crappy fuel mileage and incomplete combustion with black smoke, I will get the system repaired this week. Bundt-cake alloy wheels that I've been saving my money for will have to wait.
Reply With Quote
  #8  
Old 11-28-2004, 09:14 AM
Registered User
 
Join Date: Sep 2004
Location: Canada
Posts: 495
Saw a discussion about Harley V-Twin pipes on American Thunder one time. They were dyno testing various open pipe and open header arrangements on a 1600cc S&H motor. None of the setups had mufflers, but the various pipe lengths and configurations made big differences on the Dyno. Seems to me this would have little to do with back-pressure, as there was nothing there to create back-pressure. The discussion was about finding the best "tuned" pipe configuration. Honestly, I don't really know what this means, but it suggests that if we want to run without mufflers, or with custom mufflers, it's best to take the overall pipe length into consideration.

Dave
Reply With Quote
  #9  
Old 11-28-2004, 02:17 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
I'd replace the mufflers. Ansa and Eberspaeker are good, Borsal a bit less so. Best is Timevalve stainless, but that will be pricy (although sometimes less than the OEM ones, belive it or not!).

The reason you don't notice much difference in sound is that the resonator is rusted away internally too, so you really don't have any muffler at all. It will be quieter with new ones.

My brother needs to investigate a new exhaust on the 75 -- I can hear it badly in the house when he stops over.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
Reply With Quote
  #10  
Old 11-28-2004, 02:32 PM
Banned
 
Join Date: May 2004
Location: Varies
Posts: 4,802
I would scavenge junkyard parts before I rigged-up an expensive experiment, dog.
Attached Thumbnails
Does a '79 240D need a rear muffler??-dog.jpg  

Last edited by TwitchKitty; 11-28-2004 at 02:40 PM.
Reply With Quote
  #11  
Old 11-28-2004, 07:34 PM
Registered User
 
Join Date: Jul 2000
Location: Exeter, NH
Posts: 139
There is a magic length and it has to do with the number of cylinders and the exhaust duration i think.
I believe the resonator location has more to do with the tuning of the exhaust in the benz then any thing after it.

__________________
82 Rabbit diesel (first d), 84 Jetta turbo d (300k when sold), 83 240d (305k when sold), 84 F250 6.9d w/Banks turbo(parts truck), 86 F250 6 cyl.gasser(waiting for 6.9d), 84 300d ( 347k Sold 8/04), Y2k New Bettle TDI (185k miles), 95 740IL (wifes), 87 300TD (206k Sold 7/05), 05 Passat TDI Wagon
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 01:25 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page