Changing the Exhaust pipes in the w123 280CE

Reading Time: 5 minutes

There was this annoying hole in the exhaust from last summer. It was the thin sheet under front muffler that had cracked and I had it welded just before the MOT last year. Unfortunately the job was poorly done by the workshop. Another lesson learned on why we should fix our own cars…. The fix ended up costing almost as much as the new pipes, so that was also dumb. On the very day before this summers epic 3000 km road trip of crossing Norway I had to change the entire exhaust system. The pressure was on to get it finished before the trip!

The poorly welded exhaust only got noticeable few weeks before the upcoming road trip, but another car was planned to be used so there was no pressure initially. Then because of circumstances it was decided to use the 280CE after all and the exhaust leak needed to be addressed asap. I decided to swap out all the pipes since some rust was starting to appear in the pipe welds and its easier to just swap the whole thing at once.

I ordered the exhaust less than two weeks before from Germany and it arrived two days before the road trip was starting. Just in time. It only costed me 500$ which I think is a bargain for a classic car! The quality also seems very good as well.

Welded front muffler w123
Poorly welded front muffler. Now junk.

Stage 1 – Getting the car up in the air

You need some good space to wrestle with the large exhaust system under the car. I drove the front of the car up on ramps then lifted the back of the car on jack stands so the whole body was up in the air. I leave the tires on for extra safety and don’t lover the jack either. Also make sure to block the front wheels from rolling on the ramps. I’m a fan of redundancy and here I even placed a couple of jack stands in the front which is kind of unnecessary, but makes it feel somehow safer.

Car on jack stands
Car up in the air. Potentially dangerous and safety should be on your mind. Here I have redundancy by leaving the jack in place and using redundant jack stands. Not recommended to be under the car during an earthquake…

Stage 2 – Removing the old pipes

This is usually the most time consuming job involving rusted fasteners and wrestling with stuck pipes. I was planning to only change the pipes up to the down pipes, since the down pipes are in a really good condition compared to the rest of the exhaust. The issue then become separating the down pipes from the pipes underneath the car.

exhaust clamps
Front exhaust clamps

I started removing the clamps for the front pipes and loosening the system from the transmission mount. Then unhooking the four rubber donuts from the rear muffler. To avoid too much stress on the pipes I placed something under the rear muffler for it to rest on, in this case a tree stub.

rear muffler 280ce
Rear muffler resting on a wood stub

Then the issue with sliding off the exhaust system from the down pipes. They were extremely stuck and you’re not able to twist them since it’s a pair of dual pipes. I was first trying to push them out with putting my entire weight with my legs and kicking. Then I tried heating the outer pipes with a heater torch. After a while struggling with no success and them not moving at all I had to make a drastic decision. I needed to cut them out without damaging the inner down pipes. This would mean the old exhuast would be trash, but it’s old and not worth much anyway.

cutting the exhaust pipes
Cutting the exhaust pipes.

In order to get the old outer pipe off, it needs to be split and then removed. It would be impossible to try pushing them off otherwise. I started by cutting the pipes across a few centimeters before the mating point. Here I used an angle grinder with a thin cutting disk for about half the way, then a manual cutting saw blade for the rest. A bit tedious, but will get the job done. The best would be to use a hack saw which is much safer than an angle grinder and faster than the manual saw. However I don’t have one. Maybe now it’s a time to acquire one?

exhaust pipes cut
Pipes are cut and also a slit is made lengthwise with an angle grinder. Care is taken to not cut all the way through to th einner time.

After the pipes were separated I could remove the old exhaust system. The old stubs of the outer pipes are just as stuck and a slit have to be cut down the middle and care have to taken in order to not damage the inner tubes. The only tool for this is an angle grinder. Watch out for sparks in your face!

Split the pipes
Split the pipes with a sharp punch and drive it in with a hammer. Eventually the metal will split. Use ear protection since it tends to be very loud.

When there is a slit along the length of the pipe I could use a punch with a sharp end and drive it into the slit until it grew larger and eventually the pipe will split along its entire length. Then it was super easy to remove the outer pipe.

Splitting pipes with a punch
Splitting the pipes with a punch. Super easy!

I was surprised of how effective it was, and it was sour that I wasted so much time trying to free the pipes with different methods before I ended up doing this. I was also surprised to find that there was essentially no rust that was binding up the pipes, instead it looked like the metal had expanded into each other and exhaust coke had made this kind of glue between them. Now that the old exhaust was removed, I could mount the new system on.

Stage 3 – Fitting the new pipes

This was the fastest part of the job. It was basically lining up the three exhaust part components, putting on the clamps and tighten them. When the full length is assembled I could slide it under and mount it to the down pipes. Don’t forget to slide on the clamps before joining the exhaust pipes.

Hangers different from old system
Shape of hangers different from the old system.

I found having some help with the assembly part is useful due to the quite heavy and large part that needs to be aligned, but also doable alone if you plan all the moves ahead in time.

The exhaust kit came with four new rubber donut muffler hangers. These rubber hangers crack at an incredibly fast rate due to the heat of the exhaust and they rarely lasts more than 1-2 years before they break.

New exhaust system
New muffler being very shining, almost looks fake.

Stage 4 – Road trip

Luckily I managed to sort it out the evening before and could leave the next day.The road trip went fine and went without issues all the 3000 km. The tail pipes of the new exhaust have a slightly different shape and the heat reaches the rear bumper a bit more making a subtle bluish tint on the chrome which is quite cool.

280CE in Lofoten

I have the habit of doing jobs in hurry lately where I needed to travel shortly afterwards. Unfortunately this introduces a lot of stress and takes the joy out of fixings cars a bit. I need to plan better indeed.

Cheers, Robs out.

How to Remove the Exhaust system

Reading Time: 2 minutes

Removal of the plumbing

Removing the exhaust system may be necessary for a number of reasons. If you are replacing it then obviously you end up removing the old, but often I find the necessity to remove it for gaining access when doing other jobs. This job can be considered a simple one, but often it is not! There are pitfalls and it’s not easy dealing with these heavy tubes under the car.

What do you need?
Jack stands
Blocks of wood
Spanners

Lets get started!

Decide whether to remove the entire exhaust or parts of it. If the exhaust is old I will warn you that trying to separate the tubes will be extremely difficult sometimes. If it is a single tube exhaust like the smaller engines or diesel versions, then you might be able to twist the tube around to loosen it. If you have double tube exhaust systems I will discourage you to even try and simply remove the whole exhaust system from the beginning, talking from frustrating experience.

Jack up your car, it needs to be quite high in the front so you have enough room for the downpipes under the car. Then support the middle and the rear muffler with wooden blocks or even better if you have spare jacks, so you could lower the exhaust fashionably. Then take off the four rubber hangers on your rear muffler.

rear muffler supported with wood
Support rear muffler with wood or similar

middle muffler supported
Middle muffler supported by jack

Depending on your exhaust system it is most likely secured in other ways. In older Mercedes like the W123 it is clamped on at the transmission. Remove these clamps now.

Then the exhaust is only secured at the manifold-downtube. This is your most difficult job until now. The bolts are quite difficult to get to and your spanner will have very little room, a spanner with racketing function comes in handy here.

Exhaust downtube w123
Exhaust downtube attached to manifold

On the M110 engine, each down tube is hold on by two bolts, and they always are rusty due to the heat. Use lots of wd-40 to soak the bolts.

When you have loosened all the bolts, the exhaust will not smash into the ground since you already have supported it. Then just lower the exhaust slowly and wiggle out the downtube from the engine bay. If you have some wooden plates under the car the exhaust should slide out nicely eithout you scrathing it on the ground.  You should now have removed the entire exhaust. Congrats!

Exhaust system 280ce
Entire exhaust system detached

Bonus tip:

If you are persistent to separate the exhaust to eliminate the need to remove the entire thing, you could use a gas torch to heat up the tube at the attachment point so it will loosen up, no promises though.

gas torch on exhaust
Using a gas torch to heat up the tube