R129/M119 Engine Wiring

[JCW1]

Shortly after acquiring my 500SL about 3 years ago, it became clear that it was one of the few remaining 1993 cars that hadn't had the engine bay wiring changed from the bio-degradable stuff that MB used for a few years in the early 90's.

The most obvious signs were at the ends of the Cam Position plugs but the car was running ok so I decided to let sleeping dogs lie!

About 6 months ago, the car started to regularly drop into limp mode but due to pressure of work and life in general, I didn't have any time to do anything about it...............until today.

Took the day of work to remove the offending wiring and the throttle body so that I can send them off to be refurbished.

As stated, the cam position plugs were a bit of a mess but the wiring that runs in the tray above the fuel rail didn't seem too bad.

However, taking a random slice into the TB cable and the full horror is revealed. Judging by the green copper strands, the insulation has been gone some time. In fact, I'm amazed the car ran at all.

Thought I'd share some pictures, in case there is still anyone else on original wiring.

 

[Druk]

Where do you send them to be refurbed?

 

[bing]

Refurb a wiring loom ? That's a monumental task ! Interesting who and where ?

For M119s usually an MB replacement is the only way.

 

[BTB 500]

Yikes, great pics. I guess an SL is the sort of car that would survive the longest on the original loom if only used as a 2nd/3rd car with low mileage etc.

I also thought replacement was the only practical option ... keep us posted.

 

[JCW1]

So the company that do the work are Si-Leck in Kent. I found the link in the W124 Wiring 'sticky' at the top of this section, following a Google search.

Their core business is Motorsport wiring but they also offer this service. They take your old loom, de-solder all the plugs/sockets and then rebuild the loom using fresh, motorsport quality cable. The owner, Simon Lambert, was very helpful and suggested that they even send you a couple of photos during the 'build' of your loom. They don't advertise the service generally but it’s something they will do for MB 'enthusiasts'. I'm not sure I should mention the price but to do both the loom and the TB (including VAT and Carriage), there is reasonable change from £500.

I'm also not sure about the advertising policy on this Forum but I think people who are interested can find the details from the info I have given.

 

[Doodle]

Have they mentioned what they do in the event of knackered connectors? Usually if the wiring insulation is shot, the plastic connector casings are not far behind.

 

[JCW1]

Hi Doodle,

No, it hasn't been mentioned but I'm not sure your logic holds in this case. The wiring issue isn't due to age its due to a failed experiment in biodegradable insulation. My connectors seem fine.

To be honest, I am working on the assumption that Si-Leck have done this before and have received positive feedback on the net. If there is going to be a problem they will hopefully be able to assess my loom when it arrives and let me know. Worst case is that they can't fix my knackered loom but if that happens, I'm only down the £8 it has cost to send.

To me, that seems to be a price worth paying. Other than that I am no worse off than I was.

 

[Doodle]

I'm afraid I'm operating from practical experience.

I'm fully aware of what causes the wiring issue, and those same reasons also have a detrimental fatiguing effect on other plastic and rubber elements in the engine bay, such as the connector shrouds and the corrugated wiring conduits, which become cracked and brittle. The camshaft sensor connectors are usually the worst as they're trapped behind the distributor shields.

Unfortunately I can't find the pictures from the last 129 I assessed, that had a perfect example.

 

[Doodle]

Sorry, this isn't the pic I wanted but it will do for now

The top circle is where a crack has formed and part of the shroud has flaked off. The bottom circle is the start of a crack which runs round under my thumb, covering half the circumference of the connector.

 

[JCW1]

Hello again,

Thanks for your clarification of the point about the connectors and maybe, in general, you are correct as you clearly are speaking from experience.
However, in my specific case, the connectors seem to be pretty good, with the plastic shrouds not at all brittle and the latch clips still intact. I would concede that the conduits are aged and it wouldn't take much to break them but I was fortunate (or sympathetic) enough not to.

Here is another of my connectors. It looks ok to me and unlatched and latched fine. This and the Cam Sensors, to my mind are the easy ones. It is the cylindrical plug in the background that I have no idea how they will deal with but trust they must have a way.
I guess in the end, time will tell and I'll post the results.

 

[Doodle]

Thankfully the cylindrical ones are usually fine, they have a bit more meat to them. From that pic your connectors look in fairly good condition, so it would seem promising.

 

[rorf]

Bad luck, I do not envy you

 

[hotrodder]

Most, if not all, of the connectors are available seperately. They're typically supplied pre assembled/wired with enough cable to reach the ECU. Many of the smaller plugs are dirt cheap however the larger ones can be 'kin spendy which is a double whammy in that these are often 'heat molded' to weather proof 'em i.e. even if they're in good condition you have to either cut 'em open and then glue/bond them back together afterwoods or leave the wiring inside alone and just reinsulate/rewire upto the plug

The MAF (on the m104 engine anyway) is a good example, 1996 Mercedes Benz E320 Base L6 3.2L - 1405400081 - Mass Air Flow Connector With Harness - ES#1680728
£85.32 from Inchcape. Coolant temp sensor is another spendy one IIRC at around £50

I've no idea what Si-Leck do/how they go about things but given their reputation i'd have thought they'd let you know about any damaged connectors and wouldn't be surprised if they have sources for some of them as i doubt they're all unique to MB?

Things may have changed as at least some of the w124/m104 upper engine looms have risen from crazy expensive to insanely expensive but i've got a vague recollection that looms for the m119 were (relatively speaking!) more sensibly priced... random r129/m119 loom part # ffrom google images = £642.60 http://www.mercedes-benz-parts.co.uk/index.php?option=com_virtuemart&sku=a1295407705&Search=Go&page=shop.product_details&flypage=shop.flypage&option=com_virtuemart while for the w124/m104 they seem to range from nearly £900 to over a grand now!!

 

[JCW1]

So a quick update.

I had a call from Simon at Si-leck today. My loom is completed and the throttle body rewire will be completed on Monday so this will be just over 3 week turnaround. Not a problem for me.

I discussed the issues of connector removal and was told there were no problems as they have developed a tried and tested technique for getting them apart without damage. On re-assembly, they are glued together and held in a jig, under pressure, until the glue has cured.

Once I have got the loom back, I'll post some pictures and people can judge for themselves.

 

[Uberwagon]

Will be very interested to see this as my 500e loom is an original from 1991 with 236,000km on it.

Dave!

 

[jaymanek]

500E looms arent that expensive... I replaced mine recently.. Wasnt a lot more than the OP is spending to have an aftermarket loom made.

 

[JCW1]

Will be very interested to see this as my 500e loom is an original from 1991 with 236,000km on it.

Dave!

Do you have a problem with your loom? My understanding is that looms prior to 2003 are OK.

 

[JCW1]

500E looms arent that expensive... I replaced mine recently.. Wasnt a lot more than the OP is spending to have an aftermarket loom made.

Interesting, your input is a bit late for me but might be helpful to others if you can post a link to your source.

Hotrodder posted a link to a loom for £642 (with 10% discount) which was certainly cheaper than the anecdotal stories of looms costing £1000 but still way more than I've paid (£300+VAT).

As it happens, regardless of the price, I'd rather spend my money on a quality replacement loom from a UK independent supplier than give MB a penny towards fixing a problem that everyone knows they caused in the first place. These loom issues should have (in my opinion) been fixed as a factory recall years ago.

 

[JCW1]

Few pictures of the refurbished loom

 

[JCW1]

.......and a few more