W124 Dodgy Harness - which engine models to avoid?

[mike65]

Hi

I'm getting closer to buying a late w124 with the 2.0 16v engine (1994). I know of the bio-degradable harness issue but can anyone tell me which engines have this "feature" or are they all afflicted?

Mike.

 

[television]

You should be OK from 09 92 on.


Malcolm

 

[LNM]

Malcom

Shiiiiiiiiiiiiiiiite , I thought the looms in question were implemented later than this ? Bolix if not cos mine's registerd May1992.

 

[Bolide]

Harness

I wouldn't worry too much about the wiring harness. They're easy enough to repair. I've seen a £180 bill from a Mercedes Main Dealer to repair one and an independent will be cheaper. It's only wires with connectors each end...

Nick Froome
www.w124.co.uk

 

[television]

Malcom

Shiiiiiiiiiiiiiiiite , I thought the looms in question were implemented later than this ? Bolix if not cos mine's registerd May1992.

05-92 comes before 09-92 also a 05-92 car is a different series of car to a post 09-92 car, Sorry you cant count, help is available.

Malcolm

 

[Apial]

You should be OK from 09 92 on.


Malcolm

Are you saying that 2.0l engines from Sept 1992 on(wards) are OK? This certainly is not the case with the M104 engines with HFM.

 

[kth286]

Guys

The wiring harness problems affect mainly the straight 6 cylinder 3.2 & 2.8 litre engines (type 104) with the coils buried down between the twin overhead cams under a cover and over the spark plugs.

This engine was fitted to many cars across the range starting about 1992 and continued until the S class car was phased out in late 90's.

So, the cars involved include:

124 E class

202 C class

210 E class

140 S class

129 SL sports

In addition some V 8 engined cars from around the same period are experiencing the similar problems.

Getting back to the 104 engine, the problem starts at the feeds from the main rubber 'strapping' to the individual coils, all hidden under the top metal cover.

The plastic covering over the wires to the coils which are further hidden under a fabric cover which needs to be snipped open to reveal the flaking insulation, cause the bare wires to touch each other and the coil/s to short out.

If coils are replaced without attention to wires, then ultimately the ECU will get shorted, and is expensive to replace and reprgramme.

Ideally the whole engine loom has to be replaced at a cost nowadays of something like £550 plus fitting costs at around 3 to 4 hours (by someone thats done it previously) or longer.

You are really talking about a £1,000 job for a proper long term solution to a car which you intend to keep, and should be used in negotiation when purchasing a car.

It seems the dealers may have repair kits at around £95 per coil (and you need 3) and labour on top, BUT I would not go down this route for a car you intend to keep, as other areas of the harness will by now be very brittle.

Regards

 

[television]

Malcom

Shiiiiiiiiiiiiiiiite , I thought the looms in question were implemented later than this ? Bolix if not cos mine's registerd May1992.

Sorry if I was rude to you, I miss read your shiiiiiiiiiii bit, so sorry.

Malcolm

 

[mike65]

Thanks, I had a feeling it was the 6 pot engines with this issue.

Mike.

 

[turnipsock]

I had a to replace the harness on my 320CE last year. There is a thread with pictures somewhere.

http://forums.mercedesclub.org.uk/showthread.php?t=10829

I'm not sure where this idea about 'biogradable' insulation comes from. What is the point, it can only produce a failure or a fire.

I think what happens is that on the six pots there is a few wires that run along the top of the engine, in an area where there is a fair amount of heat. When you come to change the plugs and have to move things, you find that the insulation has become hard and brittle and it falls apart.

Try telling your house insurance company that you have rewired your house with 'biodegradabe' wire and see what happens.

 

[SJMaxson]

So my 1994 E220 should be ok?

 

[television]

So my 1994 E220 should be ok?

Yes the main issue was 1992, some of the guys in the USA with warm humid climate had worse problems than us.
the kit is easy to fit though and the cost is only 4 tanks of fuel. It can be done yourself.

malcolm

 

[pongee]

1993 W124 200e (16v)

My father has the above car which was privately imported from the UK. It is the 4 cyl version of the multivalve engine previously referenced (M1xx - not sure), and like the 6 potters, uses a pair of ignition packs in the head.

We have had to replace the engine wiring loom twice now, with the price here also hovering around the GBP500 mark. We have also had to replace the throttle body twice also, and is another known weak point of the engine. Apart from noisy tappets, the rest is fine.

As a suggestion prior to your purchase, check out the E220's, as the 200's are rather lethargic. I know 200cc isn't much, but on the road it seems to make a lot of difference.

All of the above is why I bought a '92 260E for myself

Cheers,

P.

 

[w124nut]

I would advise against part replacement of a wiring harness. If one part that you can see has broken insulation, then you can be assured that other parts of the harness that you can't see has also dodgy insulation.

My advice is to get it fixed at a good independant mercedes garage. The financial outlay for my harness cost £700 which is nothing when compared to replacing coils and ecu's etc.

 

[television]

I would advise against part replacement of a wiring harness. If one part that you can see has broken insulation, then you can be assured that other parts of the harness that you can't see has also dodgy insulation.

My advice is to get it fixed at a good independant mercedes garage. The financial outlay for my harness cost £700 which is nothing when compared to replacing coils and ecu's etc.

Who do you use in Sommerset for an indi.
thanks Malcolm

 

[3146bj]

You must be lucky. In Australia it seems to be every German or Swedish car built after about 1983 when the Greenies managed to have some good heat resistant plastic insulations banned because they released some "toxic" materials. That's the story from MB, Volvo, Audi and VW experts. How true it is nobody knows but I've had to replace engine bay wiring on a Volvo and a W124 and the auto elecs said it was a common problem on both cars. The insulation on all the wiring lost the plasticiser and broke up as soon as it was touched. The Volvo was easy - a few lengths of wire and a handful of connectors. The Merc was just a little bit too hard for me and MB refused to supply a wiring diagram so an OE harness was used.

 

[television]

You must be lucky. In Australia it seems to be every German or Swedish car built after about 1983 when the Greenies managed to have some good heat resistant plastic insulations banned because they released some "toxic" materials. That's the story from MB, Volvo, Audi and VW experts. How true it is nobody knows but I've had to replace engine bay wiring on a Volvo and a W124 and the auto elecs said it was a common problem on both cars. The insulation on all the wiring lost the plasticiser and broke up as soon as it was touched. The Volvo was easy - a few lengths of wire and a handful of connectors. The Merc was just a little bit too hard for me and MB refused to supply a wiring diagram so an OE harness was used.

I said earlier that with cars from parts of the USA had many problems, it also applies to high milage cars here through the heat built up under the bonet. it effected the SL even more (124 based) because of the extra goodies, the worst year on USA cars was 92. I have never seen an MB wiring diagram as such. If when the harness failed it did not go quite as bad, one could have coppied the original as all of the bits on their own are available.

Malcolm

Malcolm

 

[w124nut]

The independant garage I use is MBS in Exeter. Not exacly local to me and is a 30 mile drive to get there. However I think that they are worth it. I have also used Cornerstone at Ilton.

Television, sorry for the delay in responding.

 

[LNM]

Malcolm

LOL, if you look, you'll see I spelled "turd" wrong in the word registered too !!

No offence taken !!

 

[turnipsock]

The proper Merc harness has all the plug/connectors lying perfectly. It's a very well made piece of kit.