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  #1  
Old 01-27-2003, 10:56 PM
David C Klasse's Avatar
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Join Date: Jan 2001
Location: Mission Hills in the City of San Diego
Posts: 2,355
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.

D)

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.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #2  
Old 01-28-2003, 12:18 AM
ThrillBilly
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Posts: n/a
suspect N start switch

david, sorry to hear of the problems, especially the harness.

im not an elect expert, and do not have a schematic to help, but...

i had the N switch die twice on a previous volvo. stop at "insert favorite place here" shift to P, turn off car. return later to find car totally inop. 1st time had no clue. indy replaced switch, all is fine. approx 2 years later, same thing again. no amount of "fiddling" with the switch or shifter would enable the circuit. replaced again and it held as long as i owned the car.

i would begin at the N switch. good luck! - benton in atlanta

PS- i would think that the N switch is on a different harness. im guessing you replaced only the MAIN engine harness.
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  #3  
Old 01-28-2003, 05:44 AM
David C Klasse's Avatar
CheFrac is Back!
 
Join Date: Jan 2001
Location: Mission Hills in the City of San Diego
Posts: 2,355
Arrow

Yes, no amount of fiddling or anything will get it to start. Tonight I had it towed home after trying to start it for an hour. The moment the car was off the flat-bed, it started right up... GO FIGURE! GRRRR... it's quite a nuisance.

The part is cheap, so I'll go ahead and order the safety neutral switch along with the flex disc and idler arm.

If the car has been sitting for an extended period of time (ie Overnight), it always starts... no problem.

The tow truck driver tonight suggested maybe the starter overheating? We'll see.

Thanks for the input.

BTW, this is the FIRST time that I have ever had to tow my car... and I guess, in the end, it didn't really have to be towed anyways! Not too bad for nearly 140,000 miles.

PS: I snuck a pic of my baby benz's first trip on a tow truck! I'll post the pic later.
__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Last edited by David C Klasse; 01-28-2003 at 05:51 AM.
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  #4  
Old 01-28-2003, 09:57 AM
Registered User
 
Join Date: Dec 2000
Location: Battle Ground, WA
Posts: 576
Neutral safety switch...

Hi David,
You didn't say what your car is, (Seems like you used to have a 280) but if it's transmission is situated like the one in both my Mercs was, it's actually mounted on the transmission itself, on the left side where the shifter rod exits the transmission case. The wiring harness comes through a hole in the tunnel very close to the location of the accelerator pedal, and there's a connector right there. You might see if the connector is loose or damp, and you can always bypass the switch connections for the starter circuit as a test, there's only 4 wires in the connector - 2 for the backup lights, and two for the starter circuit.
You could always replace the whole thing with a 4.3L V6 and 700T4 Tranny like I did on my '82! HAH! (I stilll haven't had any problems at all with the conversion)

Good luck,
Richard Wooldridge
'82 300D/4.3LV6

Etc....
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  #5  
Old 01-29-2003, 11:39 PM
David C Klasse's Avatar
CheFrac is Back!
 
Join Date: Jan 2001
Location: Mission Hills in the City of San Diego
Posts: 2,355
Just an update...

All the parts came in today. I'm having them in stalled tomorrow. I'll keep you posted. BTW, I ordered 2 day shipping, and they came within about 24 hours! I ordered from PartsShop & FastLane... great, fast service.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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