I've reported this anamoly in the past. My 1988 560 SEL is still stalling intermittantly. This morning, traveling at 60 MPH, 27 degrees out, tach goes to zero, car is off as if I turned the key to "off", I pull over to slow lane, coasting now at about 40 MPH, car comes back "alive" and drives fine. Total time was about 15 seconds. I have replaced cap, wires, coil, rotor, and fuel pump relay. If the pattern continues, I'll not likely see this again for another 2-3 weeks. Very bizarre. Any one out there have suggestions as to where I should look next? Thanks for your input.

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Woody

"Tach" input lost, making the fuel pump relay think that the engine is no longer running?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

well i've had 2 cars do that very thing. both times it was with the ignition switch. start looking from the switch out. i wouldn't be looking at the secondary system i would look at the primary electrical system.

save the parts you took off they are probably ok.

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Thanks Much!
Craig

1972 350sl Red/Blk 117k
1988 420sel charcoal/Blk 140k
1987 420sel gold/tan 128k
See My Cars at:http://mysite.verizon.net/res0aytj/index.html

Pound it to fit then Paint it to match!

There is only First Place and Varying degrees of last!

Old age and deceit will overcome Youth and Enthusiasm every time!

Putting the square peg in the round hole is not hard... IF you do it fast enough!

Old enough to know better but stupid enough to do it anyway!

My 88 560 sl did the same. Your post of 1/29 about intermittent no start fits the ignition switch problem too. Failure of other electrical components such as radio and blower when engine dies would be a positive indication of master electrical failure verses an obscure ignition part.
The switch can be had for about $40 on-line. DIY replacement (on the 560-sl) was < 1 hour. After replacement, it was apparent that the old switch could easily have been restored with contact cleaner and emory cloth.

mostly happens on 103 engines but very
possible on an 8. suggest taking a long screwdriver or rod and gently moving the wire
to the crank sensor around. it's a shielded
wire running down behind the left cyl head
and will disapear under a plastic cap by the
trans engine joint.

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fabulous!

Interesting that more than one of you suggest the ignition switch...is there a procedure you can offer me so that I can disassemble and inspect? The crankshaft sensor has not been checked...what should I look for and can one also explain this replace procedure? Thanks! You all are very helpful!

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Woody

I'll be under the car tomorrow replacing the track rod mounts. While there can anyone tell me where and what I should look for in regards to this "crankshaft position sensor"? I hear I should not confuse this sensor with the TDC sensor which is located in the FRONT of the engine? I understand the crankshaft sensor is at the rear by the flywheel? As I recall I believe each time my car has exhibited this anamoly, the other electrical devices stayed on (radio etc.) hence my reason for looking at this sensor. Any help out there??? Thanks!!!!

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Woody

see post above

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fabulous!

I appreciate your response Devil. I have come across lit. that describes the sensor on the crankshaft as a "TDC Sensor" and it is not related to engine management but rather diagnosis only. The crankshaft position sensor is located to the rear of the engine near the bell housing, I believe, and is in fact the sensor I should be concentrating on. Is all this correct?

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Woody

yes sir, this sensor serves only one purpose in life, to tell your ignition system that it needs to go to work. like i said it is common on the
103 engine for these to act up.not as often, as say a o/v relay, but it does happen.

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fabulous!