I don't think the problem with the engine wiring harness issue is a discoloration of the copper wire, it's that the insulation degrades, cracks, and falls off, allowing the wires to short out.

There are other places to check for failing insulation. You can use a utility knife and carefully slit open the black fabric covering of the wiring harness portion that runs across your firewall.

It will be real obvious.

It is characteristic of this problem to surface after the harness has been handled, in particular after a head removal and head gasket replacement.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I agree that discoloration has nothing to do with the condition of the wires. Insulation do affect the condition of the wire. Since I am not getting spark on some plugs I wen't to ckeck the condition of the fuel injector wires. I did not get any shorts or partial short and ground to the positive side on any of these wire. When I turn on the ignition, I got 11.99 volts. So, I presumed the problem wasn't there. I never had any problem with the wiring harness before nor gives me indication that the harness is deteriorating. I did sprayed wd 40 on all injector wire sockets. I will try to spray a contact cleaner just to be sure. But, the voltages and resistance reading at the plugs give me a good reading and no intermittent readings.

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250

Rough idle fixed
Just want to everyone that the rough idling of my car was due to the deterioting condition of the wiring harness. Tom and Suginami are right. I bought the wiring harness at the MB dealer in Oakland for $565.00. It took me only two hours to install the harness. The car is running smoothly and with more power now. No more oil leak.
Here is the picture of the bad wiring harnes.

Attached Thumbnails

 

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250

When I saw your first picture a while back, I thought "Oh my!". But you really have dogged determination and an ability to follow through methodically. I'm impressed. Congratulations!

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

I agree. That was a cool thread.

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1994 C 280 117.5k, White (Good as new)
1997 Toyota Camry 149k Miles (Not so pretty anymore)

1990 190e 2.6 95k (Sold-Should not have)
1981 240d Stick ??? Miles...sold

The reason why I didn't make serious mistakes was I keep my digital camera handy with me while going through with the car repair. I took pictures every step and whenever there are steps that I am not familiar with.
My advice to others when going through the same process I went is take pictures and be careful with the wiring harness if they are still okay. Avoid bending them. You will ruin the insulation. You will find out if you open the black cloth tape cover.

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250

Very nice.
I was wondering why you decided to do a head job and also whether you tried to get MB to pay for your wiring harness.

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TomO
94 E320 Wagon, 170k, totalled in 2006
2002 BMW 525i Wagon, 75k
1991 BMW 318is (two of 'em)

I decided to do the head job myself becasue I lost trust with my mechanic when I first brought the car to fix the oil leak. He said it was the oil pan gasket so, he replaced the gasket but that did not solve the problem ($400.00). The next probable cuased was the top front seal and it was also replaced but the leak was still present(another $400.00). By careful examination, I found out that it was the head gasket that was causing the leak. With the help from all the experts in this forum I decided that I am going to do it myself.
About the wiring harness, I asked the sales rep about recal and he told me that he doesn't know of any recall regarding wiring harness. I go to the dealer only to buy parts that I needed right away. So, I did not argue with him anymore.

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250

Thanks. My head gasket looks dry but oil is dripping off the bolts that support some steel cooling lines at the right front of the oil pan and it looks to me like my upper timing cover is leaking. I've been debating when I should fix the leak. I imagine I should do the head and timing gaskets at the same time. I'll probably wait until the oil leak gets worse. Cardboard for the garage floor is cheap.

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TomO
94 E320 Wagon, 170k, totalled in 2006
2002 BMW 525i Wagon, 75k
1991 BMW 318is (two of 'em)

Tom, if your head gasket is not leaking, then I wouldn't touch it.

The leak at the upper timing chain cover is not an expensive gasket to replace to fix the leak.

I'd just do that.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

MB replaced wiring harnesses under a "goodwill" program for cars with under 100K miles. Dealerships were not required to abide by this program, so some did this cheerfully while others required "pulling teeth" to do so.

Three years ago, my harness was replaced by the dealer free of charge after I was experiencing severe loss of performance.

I admire your ability to take on such a daunting task! Mine is about due for replacement, but I am holding off until it becomes problematic (overheating, copious leaking, oil in coolant, etc.).

I thought about doing it myself...until I saw your pics (YIKES)

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Just for the record, there was no recall for this wiring harness.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

is dat de dreaded green anti freeze I see???????
better be red than dead............
William Rogers.........

is dat de dreaded green anti freeze I see???????
better be red than dead............
William Rogers.........

Yes, it's the anti freeze. The water pass through those holes to cool the engine. When I cleaned the top portion of the pistons, I covered the water inlet with rags so that no foreign object will be mixed with the anti freeze.
So far the car is running very smoothly. My wife noticed it when she step on the gas and the car responded quickly w/o hesitation.

Fred

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94 E320 Silver 210000 miles
94 740il Pewter Green 97000 miles- Retired
05 S430 4Matic
07 Lexus IS250