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Old 01-27-2003, 10:56 PM
David C Klasse's Avatar
David C Klasse David C Klasse is offline
CheFrac is Back!
Join Date: Jan 2001
Location: Mission Hills in the City of San Diego
Posts: 2,352
Question Car randomly won't start *AND* major engine knock

Firstly, my car has 138,000 miles on it now. I've been away from the shop for awhile, so I'll update you some.

Firstly, in the past few thousand miles, a fuel injector (cyl #5) failed and was replaced ($200). The computer drivers in the fuel management ECU were burned, so I had to get a new engine computer ($600+).

Shortly after the repairs, cylinders 2 & 5 died, with no results, it was determined that the engine wiring harness was worn ($800).

2 other minor repairs in order are the suspension idler arm, and a severely worn flex disc (which I replaced 30k ago, lead foot). The worn flex disc is causing a severe vibrating in the entire cabin... sounds like a 747 on take off when I'm accelerating.

And now recently, it seems symptom that my "neutral safety switch" is acting up. First time it wouldn't restart (everything works, just no engine turning) was just after i heard a snap within the shifter when I put it into PARK. I put it into Park in a jerky manner, and there was a charging cord in the way. So I assume(d) that I had broken the safety switch. I would row the shifter through the gears, and it usually starts again. But it may take an hour or two. Anyway, the no start seems to be something simple. HOwever, it's a terrible nuisance.

But then I was thinking, maybe my SO SEVERLY WORN flex disc (repair is on friday), maybe the shift box somehow wasn't properly recognizing the definite 'gear' (ie P/N/D, etc) due to the severely worn flex disc. The problem is getting worse.

So I see the NO start being one of 4 things:

A) Wiring harness replacement - maybe (a) loose connection(s) that isn't secured properly.

B) The neutral safety switch has broken and needs replacement (i have taken the entire bezel apart and fiddled with the different connections to the shifter: brake, shifter, ignition; however, doesn't mean it'll starts).

C) Worn flex disc is causing a 'misalignment' with the shifter.


I have tried using different keys, and using the key in the door... locking/unlocking.

Definitly isn't a fuel pressure thing or anything of the sort (to the BEST of my knowledge) because the engine doesn't turn, just like you're trying to start it in D or R.

I am getting a lot of engine knock lately, always when more than average acceleration is applied in either 1st gear or 2nd. I use 91 Chevron all the time. Why is my engine knocking? The MB dealer said one of my coils was weak. On occasion when the engine knocks, it will shut off a cylinder or two, requiring a restart to get smooth running (IF the damn thing STARTS).

Whaddaya think?

(BTW, all this work performed is by a TRUSTED independent mechanic (special mercedes indy for the harness).

THanks! Good to post again.
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1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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