tawom

I have a problem my mechanic cannot figure out. Mt car is a 1995 sl 500 with 48k miles. If I leave my car sitting for about 1 month it starts fine but if I drive for a while then shut it off it will not start. It backfires and chokes but will not start. If I leave it for about 30min it will then start and drive problem free for the rest of the day. This is driving me crazy. Please help. Have replaced: spark plugs, main wiring harness because it had rotted out ($500). Any ideas would be be appreciated.

Rossie

I think you have some problems with your electronic starter. My 300E and S500 Coupe also has this problem. It's mainly due because it's too old. It's quite expensive though, an original Merc one cost about US$2,600, while a Bosch one cost about US$1,800.
I hope this helps.

tawom

Do you have a more accurate name for part or part number?

Rossie

I'm sorry, my S500 Coupe is being painted at the moment, the old spoilt electronic starter is in the boot. But I think your mechanic should know what the electronic starter is.

tawom

What exactly does this starter do? When you initially wrote about the starter I immediately thought of the one to turn over the engine.

Rossie

Not that one.
I'm not very sure what it does, but that pariticular part is located in the bonet. It's about as big as a CD case. I'm sorry for not being able to remember what is the proper name for that particular part. I'll post it here as soon as I get my car back.

tawom

When you replaced this part did it solved your problem?

mechy1barry

check number 8 fuse under bonnet.also if fitted fuse in middle of engine bay near w/screen.

Rossie

I got it fixed about two months ago.

tawom

Did this replaced part fix your problem and was this the same exact problem as mine? Can you give an exact description of your problem? That kind of money for a fix is very high if it doesnt actually resolve my problem.

Rossie

My engine went dead quite often. Not exactly like yours, but it has something to do with the part I mentioned. I too, when the engine's warmed up enough, it won't cause any problems. But once, I just went out and was going to climb a slope, the engine (S500 Coupe) suddenly went dead.
You could ask your mechanic to check that part to see whether it has any problems.

tawom

Okay I will ask him about it. Electronic starter, he should be aware of what I am speaking about, correct?

Rossie

Erm... I think so...
lol...
Good luck!

csaxon

How does a wiring harness rot out? I just sold my 1974 450SL with the original harness still intact. It sounds to me (if the wiring was quality and installed correctly), that you are suffering from percolation in the fuel lines. Usually occurs in hot humid areas or with poor quality fuel. The fuel lines heat up and the fuel lines develop vapor lock. Crank it a few times and the vapor locks cause the backfire you experience. The engine will start but lug until the fuel pressure clears the vapor lock. It was a common problem when I lived in Georgia on hot humid days after driving awhile then leaving the car and trying to start it up after a few hours. You should also check your fuel lines and make sure they are not in contact with any heat source and that you have no high spots or tight bends in the line routing where air can be trapped. Sometimes the fuel pump can't easily overcome trapped air.

tawom

The rot was attributed to Chrysler using inferior parts since they merged with Mercedes. They used to replace the part but they were losing too much money and stopped.
As far as the vapor lock is it possible to remedy this problem if none of your checks are seen?