280SE W116 exhaust system

The final things preventing me from turning the 280SE from a garage queen to a rolling restoration was getting the exhaust sorted out.   It really was a mess.   The rear muffler had been changed about 20 years ago (I have the receipt), but the rest was original.   It really showed.   Not only that, but the 280SE W116 exhaust for right hand drive cars is a poor design.   It was shared with the early W123 M110 cars, and later corrected for the W126.  At that point the W126 design was applied to the W123 too.

There are two exhaust manifolds, one for the front three cylinders and one for the rear three cylinders.   Instead of going into separate downpipes like they do on the left hand drive models, there is a Y piece bolted directly to the manifolds.   There are two problems with this Y piece.   As the straight six head is quite long, it expands and contracts over time.   This eventually causes the Y piece to crack where the two arms come together.

The second is that it robs the cars of power.   In 1981, when the W123 changed from the W116 style exhaust to the W123 style exhaust it went from 112kW to 118kW.  More importantly, torque rose from 206Nm to 223Nm.   For this style exhaust the exhaust manifold ends are angled rearwards a little and there are dual pipes running under the car.

The Y piece can be seen in the diagram above as item 15.   When I got the car, I knew it was blowing from the Y piece.  I saw one for sale with a reinforced Y, so I bought it to put on the car.   Later, I realized the cracked Y piece was only the tip of the iceberg and the whole exhaust system was like swiss cheese.    To make the S class day, I used putty and exhaust patch kits to try and temporarily fix the issue.   I also drove there with all the windows open in case it was still leaking.    That is not a long term solution.

At this point it seemed silly to keep the Y piece.  It would make more sense to put the exhaust in that Mercedes-Benz should have from the outset.   Ideally I would have used later style manifolds too, but the W116 manifolds are fine if the pipes are bent around the steering box.    I took the car to the same exhaust place (Hi Tech mufflers in Darlinghurst) that did the systems on my 560SEL, 560SEC and 450SLC.   They do a great job and while they are not cheap, you’re getting a quality product they stand behind.

The layout of the system is how the 280SE W116 exhaust should have been done by the factory.   It is basically the same as how they did the left hand drive cars.   Only difference is that its done in stainless steel, which will last a lifetime.    I didn’t end up using the spare Y piece I purchased, so I’ll be selling it to somebody who wants to keep their car stock.

The car drives and sounds much better.   It does seem a bit more powerful and willing to rev too.    Next job is to fix the sagging drivers seat.