500sl doesn't like to be left standing

[pancholi]

1991 500sl with 140k on the clock. whenever i leave her for more then 4 days without starting the engine. on first start it has a really bad lumpy firing sequence. after 5 miles it usually settles down. unfortunately i left her for a week and this lumpiness is now continuous . i have tried injector cleaner. no use. should i start with the HT leads, plugs .... any help please
thanks

 

[lackofgrip]

i had this on one of my old cars, turned out to be the sparkplug gaps. but with it going away after a while sounds like damp or condensation somewhere in the ignition system

 

[television]

This problem is often condensation in the rotor arms and caps, I think it is the number one cause. cleaning them and and removing any tracking lines then oiling lightly.

malcolm

 

[Parrot of Doom]

Was just about to suggest the same as Malcolm, exactly the issue on a friend's car and it turned out to be condensation in the distributor.

Also if I could add, try firing her up at night in the dark, and watching for any arcing across the ignition leads, in case the insulation is breaking down with age. My mate's car did just this, the boots were breaking down and water dribbling down to the spark plugs.

 

[ant500sl]

Had the identical problem on my 500SL. My experience was that the rubber o- rings that seal the caps go hard with age and heat and stop sealing the cap, in turn it seams that only a skilled specialist or a main dealer will replace them with the caps.

The other issue contributing to such symptoms can be aftermarket rotor arms.
In about 1992 mercedes reinforced the arm with several ribs due to reported cracking, some of the aftermarket arms (Bremi is one make I know of for certain) are based on the old pattern. In my case I had a Bremi arm fall apart after 500 miles or so. Ridiculously expensive as they are the main sealer part does seem to do the trick. Even the genuine Bosch replacements don't seem to be as well put together as the Mercedes numbered item.

These findings are from personal experience and for the last three years while stored over winter my car has always run perfectly when started. Mind you at about 80 quid per Mercedes distributor cap and 30 odd for each arm it ought to!

Good luck
Ant

 

[davidsl500]

My problem was the other way round..


http://forums.mercedesclub.org.uk/showthread.php?t=21612&highlight=distributor

 

[television]

When I get a chance I will examine the differences on this engine and the 3valve that followed as the later engines have never had this problem.

There must be some form of sealing to stop moisture coming up from the sump.
I have some wonderful drawings for both.

Malcolm

 

[pancholi]

fantastic.....
thanks for the advice....
sunday morning here we come.......

 

[chris766]

condensation in both distributor caps

This problem is often condensation in the rotor arms and caps, I think it is the number one cause. cleaning them and and removing any tracking lines then oiling lightly.

malcolm

Hi I have an inheriant problem with both distributor caps condensating. Can anyone help me please resolve this problem as Benz are unable to. I have replaced caps & rotors six times, sprayed with WD40 & silicone sealed caps, at wits end as car is unreliable (ie will not start some days until the caps are dried. Thanks

 

[television]

I think for a start I would clean out all of the sump breathing tubes and pipes, and secondly try a different oil

What is the car Chris