Longest Lasting Wiring Harness - w124 - Thread

[locry]

Don't know if my yr model counts... I have an 87, and yes, I still have the original harness. It's a diesel though, don't know if it matters.

[TROVERMAN]

Originally Posted by locry

Don't know if my yr model counts... I have an 87, and yes, I still have the original harness. It's a diesel though, don't know if it matters.

Although your year would be in the range of Mercedes' use of biodegradable harness insulation, yours probably wouldn't be affected as severely (i.e. no wires going to coil packs / spark plugs). But definitely other engine electronic sensors.

[Clemson88]

My 300SD and 380SE have original wiring. I wonder if it would help to wrap them with electrical tape then heat shrink?

[spinedoc2304]

1991 300E with 210K on it. Original harness.

What year/model did MBs start having harness issues. I heard it was 1992 onward

Nick

[locry]

Originally Posted by spinedoc2304

1991 300E with 210K on it. Original harness.

What year/model did MBs start having harness issues. I heard it was 1992 onward

Nick

Yeah, I thpught they were only the "newer 95-ish " models that had harness issues. I never knew the 87s were included.

[Kestas]

The problem was mostly for 93-95, though there have been reports of problem spillover to adjacent years.

[cmcdonnell]

Originally Posted by TROVERMAN

We had to wrap these wire ends with electrical tape...at the very end where the wires come to a plug on top of the water pump. This connector controls electric fan speed. Unplug it and the fans will run on top speed all the time.

I got a spool of heat-shrink tubing and isolated the two wires as far up as I could go into the harness. The more i opened the harness up, the more insulation crumbled away from the wires.

[thayer]

1995 e320. 200k miles. I've got three wires close to the firewall that were naked. I heat-shrinked them. No issues yet. The car is wonderful.

[berryrice]

I replaced my harness about two years ago when my 95 e320 wagon was having some issues...well it turned out to be bad fuel pumps. As I was removing the "old" harness out it felt stiff but not brittle, but I thought since owning the car for 6 years at that point that I should do it. I figured an original harness (would've been 15 years at this point) should have looked and been much more broken down like many of the forum pics showed. I looked for a little while to try to identify if I had the original. I suspect it may have been replaced before I got it (no service records). At least I have a back up..or if anyone needs one...PM me.

[97 SL320]

I had a mid 80's Volvo 760 that was suffering from crumbling insulation so I'd expect other euro cars to have suffered a similar fate.

When I was investigating purchasing a 95 SL500 ,a call to the parts dept asking about wiring harness insulation failures / availability netted the guy saying. " Oh , horrible! Jags too. . ."

To those that can see insulation crumbling, replace / rebuild the entire harness soon. It is the wires that you can't see that will cause problems from stalling to damaged electronic components to fire.

Another issue with these cars is that the entire car is wired with the stuff, it's just the engine harness that sees failures first due to the high heat. The front body harness will the be next to fail.

[gerryvz]

V-8 models from 1992-1995 had the issue (400E/E420, 500E/E500). E500 only through 1994 model year; E420 through 1995 model year.

Inline-six models from 1993-1995 had the issue. That means late 1992 production through summer of 1995.

I'm not sure about four-cylinder and V-12 models.

With the advent of the W210 in 1996, generally the issue was solved, at least on the E-class cars.

[deanyel]

Originally Posted by 97 SL320

Another issue with these cars is that the entire car is wired with the stuff, it's just the engine harness that sees failures first due to the high heat. The front body harness will the be next to fail.

The evidence of this? How do you know all the body harnesses will fail when there's been no instances of it to date? Are you not mindlessly speculating?

[gerryvz]

To date, the only "biodegradable" wiring that has generally proven to go bad has been the following three things:

- upper wiring harness
- lower wiring harness
- wiring inside of ETA (electronic throttle body)

All three of these wiring installations are exposed to engine heat and engine bay environmentals. While most if not all wiring on the affected cars is of the "biodegradable" type, much if not most of this wiring is protected and not exposed to high temperatures, so doesn't seem to break down. Not to say it won't, just that most of this wiring (excepting the three items above) haven't seemed to have abnormally high failure rates to date.

Cheers,
Gerry

[S124300]

Originally Posted by locry

Yeah, I thpught they were only the "newer 95-ish " models that had harness issues. I never knew the 87s were included.

Here in the UK / Europe, the wiring harness issue started after about August 1992, when the M104 engines, 280 and 320, were launched with fully integrated electronic injection, etc. They were available for about six months before August 1993 in the old pre-facelift body style with an old style wiring harness that didn't degrade. I don't think that MB recognise the degradation as a problem even now, but the harness issues also cover the W202 4 cylinder cars, but seemingly not so much.
In Europe the W124 was available with the M111 2.0 and 2.2 petrol engine at 130 ish and 150 bhp. The fuel economy was pretty close to the 300D variants and were therefore popular as they were a lot zippier.

[gerryvz]

UK V-8 124 models would have had the issue too, starting from late 1991 (model year 1992 and onward).