If the wiring harness's in the engine compartment failed during the years of 1993-1995 from heat, what is the likelihood of the rest of the cars wiring failing, not necessarily from heat but from time?

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1995 E300 Diesel

most things are made to fail now

search "planned obsolescence"

Underhood wiring probably sees elevated temperatures. Hopefully the vast majority of other body wiring does not so it may last longer. Actually it apparently does.

I had posted in a thread discussing engine and body wiring, I'll try to find it. It is pretty much a sure bet that the entire car has the same wiring.

There are some cars that burn down because the underdash wiring degrades. Adding fuses to every main power feed is a good idea. ( and to the aux water pump on some cars to prevent the HVAC controler from burning. )

I have worked under the dash and other parts of my '95 E300 and have not seen any insulation degradation. The PO had several under-hood cables replaced. It's certainly possible for the insulation not exposed to heat to degrade over a longer period of time but I don't have a hack on the number except "apparently more than 18 years."

The big risk appears to be single wires or small groups of wires not tightly tied in a bundle and sheathed and especially such things that are flexed regularly. These wires can have their insulation crack, break, and fall off. The bare wires then short one to another or to the chassis. Wires that are tightly bundled and sheathed may have insulation cracking but the insulation cannot come off because it is surrounded by the outer black PVC tubing and has nowhere to go.

Risk spots other than the engine compartment include the electrical cable to the transmission (NSS and reverse switches) because there's heat down there too, and the door wiring because it is regularly flexed.

FYI gassers have this problem too, it's not just a diesel thing. Throttle body cables are especially susceptible.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

C280 loom that provides the wires to the individual coils on the head.
A bear of a job to replace.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Try these threads, someone claims that each harness was made buy a seperate company, I don't find this likely.

Longest Lasting Wiring Harness - w124 - Thread

Which years or models to avoid with wiring harness problems?