Cold start problems with 1989 500SL

[Neals]

I have a 1989 500SL that has developed an intermittent fault which appears to be electrical/ignition and would appreciate any assistance you can provide.

When starting from cold the car will invariably start okay but sometimes with a bit of a splutter. Having started there is invariably an impression that the electrics briefly cut out (most noticeable because the cd player stops and restarts), occasionally the engine will stop completely and there will be no electrics to the windows for example. Putting it back into "Park" and restarting a second time has always worked so far. Sometimes the ABS light stays on, again shifting in and out of "Park" seems to cure this. Another intermittent symptom is that, once underway, the rev counter seems to flick up and down although there is no notable change in engine revs. After 5-10 miles this problem seems to go away.

Having reviewed many of the posts on this site my thoughts are that this problem could be a faulty over-voltage protector. However, the impression I have is that these problems occur with OVP only when the engine is warm and yet mine are when it is cold.

 

[ant500sl]

Had similar problems on a 420, turned out to be a loose alternator drive belt. Always best to check the simple things first.

 

[peterarmitage]

Intermittent electrical faults

I had a comparable problem in my 1991 300SL24 - I had a side light out warning, yet all the lights were fine / windows quit working. My car has spent much of it's life parked outdoors and I've discovered that the tinned connector ends of the fuses had ALL started to corrode, such that they no longer make a good contact. Check all your fuses and compare them to a new one - if you see any grayish discolouring, it may be that some of them are making poor contacts - I recently replaced all of mine and the problem went away. If your car is elderly and/or has spent much time parked outside, its a very inexpensive fix to try. It may also be that you have this problem, and others too - fault finding where there may be more than a single electrical problem can be very difficult.

 

[Neals]

Thanks

Thanks, will check drive belt and connectors. The car is kept outside, and close to the sea in Hong Kong where it is pretty humid so corrosion maybe the issue.

Neal

 

[Neals]

The solution

Apparently it was just that the battery was too old. It was replaced with a new one and now all is fine.