My R129 500SL Progress

Page may contain affiliate links. Please see terms for details.


Active Member
Feb 18, 2018
Porsche 964 + 997, Eunos Roadster Turbo, VR6, Focus RS

I tried to post in the MB members gallery but I do not have permissions, I hope it is OK to post here, I'm no spammer. I like to do progress threads on my cars, maybe I know some people here from the various other forums I poke around in, hi!

Like my other cars, I thought I would keep a diary on the progress of my 1991 500SL.

I picked this car up March 13th after viewing it a few weeks earlier. It needs a little work but the base is all there and solid, the car has 107k miles and full Mercedes dealer history up to 85k miles and then 2 Mercedes specialist services between then and up to 95k, although the 95k was many years ago. The previous owner only covered 1500-2500 a year and had it serviced by friend. Oil on the dipstick is still clear and the air filters looked fresh upon checking the car before buying it so I took his word on that, either way, I’ll be booking her in for a big service.

Upon viewing, the car had its issue, mirrors, steering wheel and passenger seat failing to operate. Roof got stuck half way although it turns out that was us being impatient as it had not been lifted in the guys ownership, drivers seat had a worn bolster, rust on wing, damage to lower rear bumper trim, broken indicator, cracked windscreen, new tyres required, wear and tear blah blah blah, various little things.

The main things for me was the engine and drive of the car, the engine is silky smooth and runs almost silent, the drive is cushioned and refined. I was sold! I love a little project and like annoying the wife with my “I’ll sell it one of others” excuse to accumulate a collection of cars.

I agreed to buy the cat if the owner could resolve the passenger seat and mirrors not working. After waiting 2 weeks, it turned out the owner made no attempt to sort these but knocked the price down, I had got bored of looking at the pictures I took of the car upon viewing and just wanted it, so that night, I became the owner of my first Mercedes, I had always wanted an R129, not necessarily in these colour, I like my silver and blacks but this kind of looks special and unlike ones I’ve seen before. Java leather (274a) and Pajett red or rot if you’re German paint (587). I thought the lower panels had been painted but according to the spec sheet in the back of the service book, this was a factory job. The car was also debadged from factory so someone felt it necessary to incorrectly badge the car with later spec badging. Front indicators too, I’m desperate for the orange originals but not £150 desperate.

So, enough babble, here she is upon viewing.







I felt hooked, really didn’t want to leave it after viewing but I normally hate unknown electrical problems, so as the seller offered to sort, I had to leave. Had I known he wouldn’t, I could have cracked on with the car sooner.

I always enjoy getting a new car and going through the paperwork, manuals and finding out everything I can about it. I must have sat up until 2am reading things, using the VIN decoder and making head or tail of everything.

Not as much paperwork as I would have liked but after calling Mercedes, they have everything from day 1 on record and will email it once I send proof of ID! Nice

It’s got a stack of fuel receipts, original wallet, books, manuals, service book.


The next day, I popped to Mercedes and order a new headlight switch, headlight wiper cap and trim surrounds for both sun visors.




Got the hard top off to air the roof out and stick the roof lining down


I see why he never used the soft top, going to have the windows replaced by a local hood specialist.


The roof is in decent condition so it’s worth saving.


I replaced both front indicators due to the drivers side having a bit missing.


I don’t think the car had seen a really good deep clean in a long time, if ever, so I started cleaning the stitching with warm soapy water after using gliptone and zaino products on the leather


Nice 50/50 shot of the grime!


I’m jumping around a bit here but I also tackled the bonnet pad, removing what was left of it



Last job for day1 of ownership was to poke around the passenger seat and investigate the module.

Found £2, woohoo and a filthy carpet which was slightly damp to clean and sort out.

So, day 2, after checking wiring and swapping the module from the working driver’s seat, I thought I would take a look at the insides of the module from the passenger side, perhaps I could save it.. I believe the car was jump started as it was so infrequently used by the previous owner, it must have died on several occasions, he wasn’t the type to have a CTEK either. So, I think jump starting has caused a few of the electrical issues on the car.

I located the issues and soldering in wires in place of the broken tracks, sadly this didn’t fix the problem. People in the UK were charging far too much for one of these so I’ve ordered a replacement from the US for less than half of the going rate here!


Just for reference of what’s inside a seat module..


Key received a clean but forgot to take an ‘after’ pic


Seats were filthy, had them booked in for looking at by a leather man so thought I’d help him but giving him a clean base to look at and work with.


Cleaned, notice the overspray in the corners from a previous leather cowboy, I later worked out that was the case and managed to get that off.


Boot floor carpet got a wet vac too while at it


As the leather man was coming and can do all sorts of magic, my centre console shutter was missing, I had suspected it had fallen down but as I only had a few days, I thought it best I order a replacement, so I ordered one in a complete wrong colour, I knew it wouldn’t be a problem.


Really looking forward to cleaning this dusty old looking thing


Stripped the boot so I could give the carpets a good wash and I noticed some crappy wiring to the electrical aerial which I tidied, also found the fuse had blown which made it work again!


Other jobs for the leather man

Damage to leather on hard top and hole in sun visor


I love these threads so keep it coming.

I wanted a 500 SL but very good ones are big bucks so I’m going for a CLK cab instead. What did you pay for yours if you don’t mind me asking?
Great work - thanks for posting. The hood windows and bonnet pad are both common items for replacement ... have done both on my car.

I replaced the cassette storage in the centre console with a plain storage bin, which is much more practical. There are also M-B parts for a CD holder or cup holders to go there, but both are a LOT more expensive.

As you now know the indicator units just slide and clip in. Make sure yours are FULLY engaged - I lost one on the M4 once :oops:

Quite common in the US to remove the headlamp wash/wipe units for a cleaner look. There's a plastic valve that stops the washer bottle siphoning out through the washer nozzles (because they are so low down) - that failed on mine.

Did you find the switch for the boot light? Lots of people don't realise it has one!
I thought the lower panels had been painted but according to the spec sheet in the back of the service book, this was a factory job.

The build sheet would only show if they were contrast colour or not. I'm sure they've been repainted from satin to gloss.
Thanks Guys, I enjoy doing these threads as its good to look back on.

Thanks for the advice Bill, especially on the indicator, I am having trouble with the drivers side one, the fit seems REALLY tight and it is difficult to get that to clip in, I'm sure it's still loose now. I found the boot light switch, purely by chance as it is missing the black trim so I wondered what the big yellow mechanism did. :) Another little part I need to order from Mercedes.

Ahh ok Doodle, I just assumed as it has 274 for both trim colours, assumed a matt finish may have a different code. The car has had a blow over so they may well have been matched then, all for the better in my eyes.

Clean key!


As a result of Dale the leather man coming out to the car, he resolved the issues I had.

That grey roller shutter, perfectly matched in Java colouring!


Damage to the hardtop, gone!


And the seat after unmasking


Very pleased with the job, it is slightly matt but he did that on purpose as it will wear to a shine. You’ll notice the colour of the passenger bolster, it seems someone had a go at this before but we’ll come this later and you will see what someone was trying to cover up!


I began the interior clean up, I really wish I had some good before shots as it was pure filth!! The car had been used without mats and there were black splodges, grime and crusty stuff all over.




No one ever cleans belt sockets!! Tooth brush and some warm soapy water do wonders!



Here you can see the difference between a bit that I have done a few passes over with the wet vac.


So much grime, the water was black at one point!


Completed boot, also had to rebuild the triangle as the rivets holding the base on had broken off!


Mat and carpets cleaned here




After the interior had every single surfaced washed, scrubbed, treated, I moved on to some electrical probs. One interior bulb doesn’t work, fortunately it was just a bulb. Phew. One of the buttons is really stiff so need to address that at some point.


Last edited:
Saturday just gone, I had a set of Uniroyal RainSport 3's fitted all round, 225/55/16's. The goodyears on the car were illegal so apart from risking the drive home when purchasing, I had refrained from using the car.



While the wheels were off, I gave the calipers a wire brush and quick paint. I'll be revisting these when it comes to cleaning the inner arches of the car.



When I got back, a courier had delivery my replacement mirror/steering wheel module, woohoo!!


This resulted in them working although I have an issue with the passenger side constantly trying to point upwards, I'm really stumped as to why, so for the time being, I have disconnected the mirror plug on the module. It did this with the previous module some something else is playing havov with this mirror, possibly the door loom at a guess or maybe a dodgy switch? The interior and drivers mirror adjust fine, the passenger mirror can be adjusted apart from upwards when the car is off but as soon as the car is on, the passenger mirror just wants to point upwards! So the car running is causing an issue here..

I had an occasional issue with the abd/asr light coming on, I found that giving the OVP relay a tap sorted things so I've got a new relay on order, it is currently mounted upside down and working fine that way but best to replace.


Also hoovered out the leafs from this area! Then the engine bay clean up began!

New bonnet mat fitted


G101 to loosen oily dirt.



The finished article




New wiper blades fitted


Fresh and plain number plates fitted


Then on to the centre shutter cover!

Thanks Grober! Keeping me busy
Upon pulling the centre cubby hole, I found the original shutter (I knew it would be there!!!) but it was broken so didn't feel bad about getting the new one done and I found an electric window button!



While off, I gave the wood a polish and wax. I wish I could get rid of the immobiliser thing which isn't used but it would leave a 10mm hole :(

So, as you may see above, the passenger bolster initially appears faded but it turned out that someone had painted it..

After I started rubbing, I noticed that there is white paint on the seat, I initially wondered if this was some sort of leather filler but I carried on rubbing and could see that this was just paint, some some gentle rubbing with rubbing alcohol started to lift this off the seat.


I'm still working on this but as you can see, it's nearly all gone, just exposing normal leather wear, so rather than someone trying to remove the paint, they decided to paint over it!!! What a joke!!!

I had given the car a very quick polish, I intend to fully machine polish the paint once the weather is better but for now, a quick polish/wax did the job so I thought I'd take some photos now that the car is at a good level.



My favourite!

And finally catching up with today, 2 week ownership anniversary, a new windscreen!


Next, new PVC windows, fitting seat module when that arrives, new viscous fan clutch, rust repair.

Electrical gremlins too, blower is only blowing up at the windscreen, I can't get it to change direction.

Wipers only work on speed 0 and 3 but I need to check the N10 relay.
DOOR MIRROR gremlins may be wiring related and if so likely weak spot is going to be at the door hinge. The OVP can often be repaired by removing the can and going over the rear of the small PRINTED CIRCUIT BOARD inside with a soldering iron to eliminate dry joints*- they crack due to vibration- this often restores function- if not confident in any repair -you can always keep it as a spare. On your age of car I think your heater problem may be flap vacuum actuator related . Switched electrically the flaps are vacuum actuated and the diaphragms can perish and leak.

* this might apply to other control modules that aren't working?
Last edited:
Looking very nice indeed.

That radio antenna seems extremely long?!
If the indicators are still working it may not be the N10. There is a separate wiper relay (K26) on the passenger side (i.e. other side from the fuse box). The switches get sticky, a quick blast with some PCB cleaner and all is well.


Users who are viewing this thread

Top Bottom