rough running C280 Fixed!

Thanks to all of you who tried to help me diagnose my poor, sick C280. After replacing plugs, wires, end caps and OVP relay, it turns out that Arthur Dalton was right in his initial diagnosis.

It was - in fact - the dreaded wiring harness. And, of course, my friendly 280 was WAY out of any warranty. However, found a great tech in Oklahoma City who treated me fairly and did the job in less than 3 hours. Will highly recommend them to anyone in the OKC area who is out of warranty and needs a reasonbly priced, master MB tech (17 years experience).

Thanks again to everyone.

[Jason Beal]

How many miles and what year was it? If you don'd mind me asking? Did you check engine light come on or no? Thanks.

Hello Jason:

The car is a '94 with 147K miles. The Check Engine light never came on. According to the tech it would likely not have come on until the engine began to really miss - which started the day I got it in to the shop. So, I was probably just in time.

When we removed the black friction tape wrap of the wiring harness, literally all the insulation was crumbling or disintegrating.
At the coil ends, the insulation under the harness had completely vanished.

Bob

[Jason Beal]

Mine is 94 too with 61k. It was running strange for a bit, but new plugs seemed to make all the difference. For now anyway. 147k sounds (from what I've read on this board) much further than when other people have run into problems. So I guess that's sort of a good thing. Good luck.

Jason

[blackmercedes]

Since many people have this problem (lately) on early W202 cars, it would seem time and not mileage is probably the thing that causes the most wear and tear on the harness.

It's nice to hear of some higher (relatively) mileage W202 cars. Many owners I meet are older folks that drive 5-8K or so a year. In Canuck-land, the average C-class buyer is about 60, so it's no wonder...

You are right on target about the "time" vs "mileage" issue. Several enlightened (experienced) senior members of this forum have made similar comments.

As to how I drive the car, it would be fair to say that moderate is not it. We average 100 or more mile per day... about 60 miles are freeway driving and the rest are big city - hard stop and hard go.

I have been extremely pleased with the over-all reliability and dependability of the vehicle. And, except for the wiring harness and some intermittent A/C and dash cluster anomolies, I've not really had any serious problems.

One More Thing:
It's always amazed me that such a mild looking car - with a six cylinder engine (I'm a product of the muscle car era) - could be so darn quick. A friend of mine just purchsed a new High Dollar BMW (well over $50K complete) and my little C280 does a pretty good job of running down the road with him. He was more than a little p'd off.

[Jason Beal]

"One More Thing:
It's always amazed me that such a mild looking car - with a six cylinder engine (I'm a product of the muscle car era) - could be so darn quick. A friend of mine just purchsed a new High Dollar BMW (well over $50K complete) and my little C280 does a pretty good job of running down the road with him."

I'd certainly agree with that.

[Princess]

I have a 1975 450SL that needs a new wiring harness. I am not far from Oklahoma, does the shop you went to work on older cars? Is 3 hours labor about normal? How much did it cost you if you don't mind my asking? Thanks!

Princess:

I'd be happy to share the info with you. Check your e-mail.