Mercedes R129 500SL - should I be scared?

I don't own one, but

1) A very good friend of mine has, and he's flipped a few in his time
2) Another friend has owned a few, and is now trying to sell one (a 320SL)

Both have owned their share of W124s, as have I.

They became a little old in the tooth towards the end of their life, but then again, they were old, and the competition had moved the goalposts, like the XK8 did, for example.

They are a pretty solid choice, but they can have some pretty big bills as well, mainly electrically. The roof can be scarily expensive to get working right (I think £1-2k rings a bell?), and can be tricky to diagnose.

Being that generation, they may also suffer from wiring engine harness issues. At the very least, the EFI (aka HFM) engines do, which include the

M104 280SL/SL280
M104 320SL/SL320.

I'm pretty sure the 500 falls into the iffy harness camp, despite not being part of the M104 family, as most Merc engine harnesses were biodegrable for the first time. This will cause no end of issues with the running of the engine, from misfires to the engine cutting out.

On a S124 E280 a mate had, the wiring harness almost cost him his relationship (he was told not to buy the car, as we discovered it had an almighty haircut, but the chap knocked the price down, so he bought it).

There is zero point in repairing the harness, as it willy simply fail elsewhere, and you will chase the harness until it's basically fully changed. A fresh harness on a 6 pot M104 is now about £800, with your old connectors being re-used, but the wiring being reterminated, so none of the old wiring is present. On a V8, I'd imagine that cost would be over £1k, given that there is more hardware to plug into.

Then you get suspension bits etc. but I think these are more reasonable in price.

They can also rot. OK, maybe not as bad as a Jag, but still, more than you think. Sills are a popular thing, so check beneath the covers and jacking points if you can, as well as under the car, generally.

Would I not get one with the above? Not at all, they are quite cool and have their place. That and compared to their contemporaries, like the :

X100 XK8
BMW E31 8 Series
Porsche 928 (S2-S4 generation I'd guess at a similar age)

These look to be much better value you could argue, and with a lovely elegance. The issues on the above are not the same, but still pricey in a number of cases. After all, they were a premium car in their day, with the height of tech in them, and time hasn't changed that.

Overall, I say be aware of how things can go, but go for it, if the car feels right.

ChasR, many thanks for all the information.

I've been doing a little more research into the different R129 models, and thankfully this particular year and model isn't affected with the wiring loom issues, so that's one thing ticked off the list.

I will take a close look at the areas for corrosion, I did notice some very small areas on the rear arches, and the front edge of the hardtop.

The hardtop hasn't been taken off for at least 18 months I was told, it will be interesting to see how it goes at the weekend with taking that off, and taking a look at the soft top.

I've been through the cars paperwork, and it has had around 3k spent on poor running issues over the last 4 years before being sold on. Idle control valve, distributor caps etc.
The car did cut out a couple of times when being moved out of hibernation the other day, I guess it could be old fuel, or a continuation of it's previous running issues!

We'll see how it goes at the weekend and make a decision from there.

I've got one ..



Bought my 98 SL500 3 yrs ago with 55k on the clock , its now on 65k so it gets used.
Did 1600 miles in it in September to Angouleme and back , easy mile muncher but a sports car it is not.
Its a heavy car so a lot of the suspension will be toast , mine req a new lower control arm , anti roll bar bushes and the cotton reel type bushes when I got it , I had genuine parts fitted so it wasn't cheap ,theres a lot of W124 underneath... other than that its had 2 services and that's all.
I tried a louder exhaust but it was hideous and didn't suit the car at all so stuck the old one straight back on .. good luck