1995 C280 will not start after plug change
 

!995 C280, changed the plugs and now it will not start. Smell fuel after crank so assume that isn't the issue. Replaced the OVP relay which did not help. There is no spark at the plugs....
Any idea what might be going on here?

Is the wiring harness that you molested to get at the plugs original? If so that would be the likely suspect.

Not sure on the harness. I am guessing it is. Is there a certain failure prone spot on these that I can patch up to verify the harness is the issue? What seems to be the failure in the harness?
Thanks

The insulation on the wiring inside the original harnesses is biodegradable, eventually leading to electrical shorts over time as it breaks down. If yours has this problem, it'll need to be replaced - I don't think you can fix it. Don't be put off by the cost of the parts, it's easy to replace.

Well I suppose that will be my area of focus then. Am i to assume the wires within the harness will be able to be identified as being the issue as I get into the wireloom? I looked at the ourside loom covering which looked good but I guess it would be inside where the problem lies...
Thanks

If I were you I would get the part number off the wiring harness, take it to the dealer and ask them whether it's original or a replacement - because if it's original it's shot, and if it's a replacement it should be fine. No need to do this if you can see crumbling insulation - just replace it. The part number is near the source plug by the battery. You may have to unplug it to find it. I tried repair but it lasted for only a few weeks. It fails first nearest to heat sources but once it's failing there it's suspect just about everywhere - and it's gotta go.

I will check that out today. Seems like a likely suspect. Itry to find that part number.
Thanks

If the insulation is breaking down, it'll be inside the loom - look closely at the connectors on top of the thermostat, you might be able to see exposed wiring there. If it's exposed, the copper will turn a greenish colour though oxidation.

Well, it is bad. The harness is gone. I am sick after seeing it. Bare wires leading to the coils. How do you not recall this? fire hazard?? could the electronics be damaged??
I don't think I would ever buy another mercedes after seeing this mess.

check out this thread:

http://www.peachparts.com/shopforum/general-information/128181-mb-wiring-harness-failure.html?highlight=wiring+harness

also post your complaint/issue to the NHTSA complaint thread listed AND
call MBUSA and ask to speak to John Hart, a supervisor at MBUSA, who claims to have NEVER heard of this problem:
1-800-FOR-MERCEDES (1-800-367-6372)

perhaps someday mercedes will address this issue (ha! i laugh at myself even for thinking this)

BTW: It only affected the 93-95 MBs as they changed the wiring in the '96 MY

There was a post not long ago about trying to start a class action or something. The thing that irks me about is that the price just keeps going up - used to be three hundred something a few years ago and is now more than twice that. You'd think with such a screw-up they could at least be a little reasonable on the prices increases. They seem to have no shame.

If you're the original owner I would definitely try for a "goodwill" replacement from your local dealer. At the least, ask for them to goodwill the harness and you can install it yourself.

How many miles on your C?

If you replace it yourself, try not to disrupt the Electronic Accelerator (throttle housing) wiring harness. You do not want to have to replace that part.

Good Luck

The wiring inside throttle actuator does have the same problem - biodegradable insulation. Another costly component, but one that should be fairly easy to replace.

I believe you can get them refurbished - mine's been suspect for a while, it's the only consistent code the car gives once the CEL comes on... I wanted to pull mine off for cleaning to see if that would help... if only I could figure out how.

Well, I have the car running again! Thanks for the help in running the issue down. I was able to seperate the wires, double checked them them they were in fact not ground out and tape them back up. Works enough to get the car to the shop to get the harness pulled as I just don't have the kind of time to do that right now.
Even the outside temp worked (for a few blocks) until it returned to is normal 137 degree reading :sun_smile
Hot out there!
Matt

And it has 103,000 miles on it.