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Old 11-27-2002, 12:40 PM
Registered User
Join Date: Jun 2002
Posts: 14
Head gasket/wire hareness

When replaceing the head gasket can one damage the wire hareness on a 104 engine? One week after the head gasket repair my check engine light came on.
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Old 11-27-2002, 01:04 PM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,234
If it is the original wiring harness then yes, I suspect it could be damaged during the removal/replacement of the cyl head. The harness has to be "laid" back out of the way during the head job.
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Old 11-27-2002, 06:03 PM
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Join Date: Jul 2000
Posts: 638
wiring harness failures

I think 'damage' is too harsh a term. More appropriate is 'discover a failure'. What happens is the insulation on the individual wires crumbles and turns to dust. That is the failure

All is well so long as nothing moves. However, any movement(from flexing in normal operation) or maintenance can cause the crumbles to shift and let the now bare wires touch and short out. That is the discovery of the failure that has already happened.

European recycling laws encourgaed the mfg's to make 'biodegradeable' wire insulation for cars. We crazy Americans simply expect our cars to last too long (of course, excluding taxes they cost 100% more here and are very profitable compared to a European sale)

Over there the original mfg has to take the car back( or be responsible for it) when it is scrapped and recycle it somehow.
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Old 11-27-2002, 07:40 PM
Join Date: Dec 2001
Location: Southern California, U.S.A.
Posts: 8,503
I agree with Kebowers. It was unavoidable and it wasn't your fault.

Your wiring harness was already damaged, but the problem didn't surface until the harness was moved.

It is almost always after a head gasket replacement that the dreaded engine wiring harness rears its ugly head.
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".
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Old 11-28-2002, 05:58 PM
Senior Member
Join Date: Sep 2002
Location: New Jersey, U.S.A.
Posts: 2,398
Doesn't anyone want to know what code(s) caused the light to come on? NeilC doesn't have a starting or running complaint does he? How about checking the vacuum supply line to the EGR and Air injection switchover valves? I've seen the line cracked (usually behind the black plastic front cover) dozens of times. That type of vacuum tubing becomes very brittle with age and it needs to be moved out of the way during a head gasket job. By the way, I'm not disagreeing with you guys about the possibility of "discovering a failure"(I like that term) such as a 104 harness, while performing other work. It's just that in my experience I'd look real close at that vacuum line. So Neil, what code lit the lamp?
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