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.

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As the SEC is the 10:1 compression ECE model, it has a different exhaust system as standard than my 560SEL.    The exhaust manifolds are two piece on each bank and go through longer headers. This is illustrated in the picture above that can be compared to picture in the 560SEL article.    This is often referred to as the ‘tri-y’ system.    Based on this, I was looking for a 560SEC performance exhaust.

As can be seen in the picture below, my new exhaust retains this feature. It is now in stainless steel 2″ pipe. I’ve saved the original pieces to remain with the car too.

The system continues as dual 2″ pipes to a single centre muffler that replaces the factory kidney mufflers.    I’ve not seen stats, but the kidney mufflers seem very restrictive.    My straight through centre muffler should work much better.    The rear muffler is also much smaller than the factory rear box.   I was looking for something with a bit more presence, but without droning at speed or being obnoxious.

In having this system built, the other thing I was basing this off was the contemporary AMG systems.   The main difference is the AMG systems came straight out the back.   I didn’t want to modify my rear bumper or have the exhaust hang low, so I used the factory cut out.    You can see the AMG system in the centre and the tips on the bottom left.

I had actually bought some AMG style tips, but due to the curvature required in the exhaust, I had these tips made up.   I think its a pretty good compromise to make sure the exhaust doesn’t impact any curbs.  My 560SEC performance exhaust sounds great and it should last a long time

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The diagram below shows the factory system.   While the Australian version of the 560 is quite similar to the USA version in many ways, it uses the standard catalyst exhaust, not the USA style.

It is a rather odd design.   the centre mufflers are generally referred to as the ‘kidney’ mufflers.    My system had been welded and patched a few times.  The kidney mufflers looked quite new, but they were not put in well, and the bends of the pipes meant nothing lined up properly.   There was also rust in the pipes between the kidneys and the rear muffler.

Instead of continuing the patch the system, I decided to replace it with a new 560SEL stainless steel exhaust system.     I wanted a system that would be more free flowing, but would still look original unless the car was up on the hoist.

The whole system was replaced from the manifolds back.   In a perfect world, I would have obtained a set of the two piece manifolds as found on my 560SEC ECE.   Those manifolds are very expensive, so I went with what I had.   There are only two joins (as seen in the picture) so the whole system can be dropped easily.  This means less chance of leaks.

The Australian version of the 560SEL is equipped with an oxygen sensor.   This has been fitted to a small join section behind the transmission.   The rearmost section has been painted black to match the original look.

The new system is much neater and I can feel an improvement in performance of the car.    There is a slight increase in engine note, but still in keeping with how a luxury car like the 560SEL should sound.    As it has been raining this week, I have not been able to test the sound at high RPM/full throttle.

With an exhaust system that no longer rubbed against the drive shaft, I was able to take the car on a longer run.   I had arranged to meet a friend from the Mercedes club for a quick catch up.  A good run for the car.    He brought his 1978 280CE W123.   As it is an early CE, it has the nicer dashboard with the burl wood and self-leveling suspension.   280CE’s are an underrated car.

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