PeachParts Mercedes-Benz Forum - View Single Post - My notes on replacing the exhaust of a W124 wagon (1995 E320)

ljsense · #1 08-16-2012, 06:20 PM

If interested, here is a rundown on my most recent job, replacing the original exhaust on my 1995 E320 W124 wagon.

The executive summary message: this was not an easy job. I would not attempt it unless you have a lift. You will be wrestling with seized steel, and due to the design, things could get very difficult. It's not just cutting bolts or pipes, it's trying to free an overlapping/fitted exhaust pipe that is connected to the catalytic converter.

OK, more detail.

My replacement exhaust pieces were Bosal (made in Belgium!) and consisted of a front silencer, a rear silencer, a left fitting or gasket, a right fitting or gasket, a 2.5" exhaust clamp, 4 M8 x 60mm bolts and 4 M8 nuts.

The catalytic converter has two pipes leading to the exhaust parts I replaced.
One is a butt joint with flared flanges and a solid metal ring in between that serves as a gasket or seal. They are joined by two sliding rings that bolt together with 2 bolts. The other pipe off the catalytic converter joins the exhaust by overlapping it by 4 to 5 inches. The catalytic pipe is on the inside of this fitting; the exhaust pipe is flared at the end and has a gasket ring made of densely braided wire. Again, this joint has two rings that bolt together with two bolts to push it tight.

These to pipes go to the first silencer, which hangs from one rubber hanger. One pipe joins the pipe of the second silencer or muffler with a common slide-over connection and exhaust clamp.

The 4 bolts to loosen the fittings at the catalytic converter will have difficult access for at least one bolt. Plan on cutting the bolts and at least one pipe to gain better unless you are lucky with heat and PB Blaster.

Similarly, it is not necessary to free the clamp; you can simply cut the pipe between the two silencers.

A sawzall makes this job much easier.

Now, to the truly difficult part: getting the overlapping pipes separated at the catalytic converter.

On my car, which still after 17 years had the original exhaust, this was enormously difficult. I heated and PB blasted the joint several times, used pry bars, an air chisel, various hammers, a plumber's wrench and a 5-foot leverage pipe.

Eventually, it just sort of tore off, leaving a bit of the catalytic pipe that was under the joint.

Ideally, I would have had more pipe to slip into the new steel, but there was just enough to work with to get the wire-braided ring into the joint and everything tight and sealed.

In summary, think twice before taking this on. The drawing or diagram makes it look easy. In reality, you are going to have to work very hard to separate strongly bonded steel, with the risk of ruining the pipe you rely on to make your replacement parts fit.