my muffler rotted plum off. After a couple weeks of the coat hanger thing I went to a shop that I had good experience with before and had them run pipe straight back (with a few necessary bends). Later I discovered that the 3 feet of new pipe that they put on is 1 3/4 diameter and not the 2 1/2 diameter that all the stock pipe is.
I have had several arguments with them about the suibablity of the smaller pipe. They are telling me that it shouldn't affect much and are not likely to replace it.
So, am I way out of line? it seems like madness to me to have a smaller diameter pipe on something that is so dependent of gulping air and expelling it like a turbo diesel and I should be insisting on the correct diameter pipe.
They said to come back with my recibt and they will do something. I suspect that we will argue some more and then they will want to hand my money back and wack their new work off.
Any comments? let is ride/ or insist on the regular size pipe

" They are telling me that it shouldn't affect much..."

That's nonsense.

First of all, the muffler shop should have replaced with a similarly sized piece of tubing, not something with 30% less crossection.

Second, it is patently absurd for them to claim that a significant reduction in pipe crossection won't affect the performance and economy of your vehicle.

Return to them ASAP and FIRMLY state your position, requesting that the system be changed to a tubing that more closely matches the original. If they decline, show them a (pre written) letter addressed to them and the BBB with a cc to the consumer affairs department of your state's Office of
the Attorney General.

Carefully document all of your actions.

If they still decline, go ahead and have the system retrofitted at a comparable third party muffler shop and then take the first muffer hut to small claims court to recover your expenses.

__________________
Never a dull moment at Berry Hill Farm.

It will effect preformance and it will increase your exhust temps . You should get them to change it back to the original size.

There's nothing wrong with no muffler but smaller piping isn't a good idea. Maybe they thought it would make it quieter ............I'm pretty sure benz engineers knew what they were doing when they made your original exhuast

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

When you do the math, and calculate the areas of the two cross sections (Area=Pi*r*r) you will find that the 1-3/4" pipe is almost 50% smaller in total area then 2-1/2" pipe. This is not acceptable. The back-pressure that this diminished area produces is not beneficial to any engine.

__________________
'95 E300 Diesel, 264,000 Miles. [Sold it]

from crooks is not unusual.
I had fights with several shop owners over the years.
A pipe 50% smaller is stupid and wrong, it can also choke the turbo.
That is a huge exhaust restriction.
Take the car to another shop and ask for a professional opinion, you may get words, but not legally admissible statements in print.
Few mechanics will testify in court or get dragged into a legal battle they can avoid, you loose money, and I know several who have been ruined by just that.
My best advice is to go to a different shop, ask if they have 2 1/2 diameter pipes in stock, if yes, let them replace the mess and pay the cost.

Any other answer will cost you weeks of your time and cash money.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

you want to hear a crazy thing that always seemed to work with me. Everytime that I had some type of problem with a dealership,shop etc i would bring a video camera along with me. I would just turn it on so they can see the red light and then just hold it in my hands as I'm discussing my issues with them.

__________________
Audi TT

Dont know why the muffler shop is trying to wiggle out of this, I bypassed my muffler and modified my air intake by shortening the pipe and diverting it towards the front for fresh cool air. Made a massive difference in throttle response, it sure runs much better now, feels and sounds powerful and best of all, I am getting higher MPG which is important now with fuel prices skyrocketting.

Angst.

I agree with pberku that its a 50 % reduction. Go back to the shop and demand they replace the pipe with the correct size.

P E H

LOL, muffler people nearly exploded when I criticized them for welding replacement sections to older pipe ends - me thinking it would make replacement of older sections tougher down the road.

Hilarious as it might sound, muffler people can be real hot-heads.... I've never seen this attitude among tire shops, allignment techs, independent garages, MB dealerships, parts shops, etc.

If it was me, I'd just sit down with the muffler shop owner and say something like: "C'mon, that narrow pipe will restrict the engine flow and you know it"..... meanwhile reminding them that I had done business with them before and am a return customer.

I made all the points 240DieselDog mentioned to the guy at the shop. Like the other poster said he was very confrontational. Even argued about weather I was a long term customer or not. If I didn't negotiate with people for a living it would have blown into a full blown shouting match. We left the conversation friday morning with him saying 'bring in your recibt and Ill take care of it'. I didn't have time to go back by but I plan on being the first person in there monday morning. I suspect that he is going to hand me my money back and go out there with a saw and cut his work right back off (which would be fine with me)
If my math is right, surface area is radius times pi. so 1.75/2 = .88 and .88 x 3.14= 2.76 for a 2.5inch pipe 2.5/2=1.25 and 1.25 x 3.14 = 3.93

Ill post what happens.

Surface Area = Pi * radius * radius
Circumference = 2 * Pi * radius


The surface area is proportional to the square of radius. If R1 = 2.50 in and R2 = 1.75 in, the surface area will be reduced by a factor of:

(R2/R1)^2 = (1.75 / 2.50)^2 = (0.7)^2 = 0.49

That's a (100 - 49)% = 51 % reduction in the surface area.


Eric

Angst,

Your math is wrong. Area is PI x r squared. Pi is the same in both equations so it will cancel out. If we are only interested in comparing the relative area of the cross section area of large pipe compared to the small pipe we can just use the diameter and square it.

Therefore: 1 3/4 squared = 3.06 small pipe
...............2 1/2 squared = 6.25 large pipe

Then: 6.25 divided by 3.06 = 2.04.

So the area of the 2 1/2 inch pipe compared to the 1 3/4 inch pipe is greater than 2. Thus the restriction of the smaller pipe would be greater than 2.

It the same fact that a 10 inch pipe will supply 100 1 inch pipes not only 10 because of the square factor.

P E H

There is some restriction from the muffler, too. I'd bet the smaller pipe is to compensate, although I'd not have used one quite that small.

You really should replace the exhaust. I'm going to use TimeValve for all of mine -- very high quality SS, quite heavy (they sell extra heavy duty hangers due to the weight). My friend Hans has started using them after some bad experience with "factory" replacements (Erbsbacher (sp?) in particular). The "factory" parts cost more, and seem to last only 4-5 years instead of the normal 15-20, a problem for the mechanic. The Timevalve should last forever. They don't LOOK exactly like factory parts (considerably more welding, some pipes are "made up" rather than bent), but so far they fix exactly.

Cost for a W123 last time I looked was about $300 manifold to chrome tip.

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!