rallymantony

Hi
New to the site. Can anyone help me? I have a 1991 SL500 that has a cut out issue. It seems to be whenever it feels like it as I can not seem to find any common symptoms. Sometimes it will do it after 10-15 miles, sometimes just a few miles and other times after 30 or 40 miles. An example, the last time was when I came to a stop at a junction I was waiting to pull out for a few minutes and then without warning just cut out. The time before that I was traveling about 60 maybe 70 mph and the again the engine just cut out and came to a stop at the side of the road. In both cases the engine wouldn't start for about 5 minutes, it makes no difference if you leave it and then try to start it or try to start it straight away. I would guess that it is electrical. Any help would be really good.

tusabes

Mercedes used biodegradable wiring insulation in these cars and it gets old, cracked and the wire insulation falls apart and shorts the wires, sounds liek that is whats happening.

pleeson

I agree.
A fairly simple check of the wires that are under the air cleaner and go to the various sensors will confirm.
A 60 minute repair in my driveway, but a $600 part...

hineywineries

I don't suspect a wiring problem, because that didn't occur until 94 and 95. I suspect a failing crank position sensor. It should be changed anyway if it is original. If your sensor has the long pigtail, the retail is about $150.00. If you have the one sans the pigtail. it is about $60.00. The sensor has a high failure rate.
Good luck

rallymantony

Thank you will give it a go and let you know how it goes.

hineywineries

Thanks for the vote of confidence, but I'm going to have to retract my statement.Since my post I've run across a wiring issue in an earlier car. I was under the impression it was only 94 95. Follow the other suggestions and check wiring. If all is good, I'd say crank sensor next.
Sorry for the bogus info.

lynns

Check the rotors and caps.

MPANZ

I had a very similar problem on my 1999 SL 500, I had the crank shaft sensor changed and the car runs perfect now.

geetarzan63

I'm having a similar issue with a 1991 500SL. Has the long pigtail. Ordered one, have it in hand, will install in the morning. This particular car is a complete no start. Began with running poorly, stalling and hard to restart, no rhyme or reason to any of it.

I'll post the result of the replacement crank sensor tomorrow.

Wayne
Austin, TX

geetarzan63

Installed the new crank sensor this morning and.....nothing. Still no spark. Any ideas?

Lee Wireless

Did you do as Lynn said in an earlier post? Check the rotors and caps.

prathermj

Check with wiring harness and replace the caps and rotors. Chances are the caps and rotors are worn out. The caps and rotors take only an hour or so to change and are cheap, relatively speaking.