Looking for info: 1973 450SL

[muppix]

Hi Gang,

I'm looking for some information to help me diagnose what's wrong with a friend's car. It's a 1973 Mercedes 450SL (fuel injected) which has been garaged for most of it's life and generally treated well. The problem? Once up at normal operating temperature she just cuts out and refuses to restart until the engine has cooled down again. While in the dead phase the engine will turn over on the starter but there's no sign of ignition.

We've had the car looked at by a local mechanic who's generally well respected in the community, but this vintage it just a little outside his field of expertise. To complicate matters somewhat, I don't have access to the car myself as it's located abroad, but I'd really like to help the guy out because I've been in similar situations myself before and know how soul-destroying it can be to not know where to turn.

Do you know about the '73 450SL, maybe some common electrical or fuel related weakness? Had one yourself at some point? I'd be way grateful for any and all information, even just somewhere to start looking.

Many, many thanks in advance.
Mark.

 

[television]

You do need to know if the spark goes when hot,, from memory the EZL is held down on a metal panel, there is a thermal paste on the EZL where it is bolted down and this can dry out allowing thermal runaway and the transistors switch off.

The CPS in not a known fault, but who knows

 

[muppix]

That's great info, thanks. I presume to fix this I could use the same sort of thermal paste that holds computer processors to heatsinks? I'll get confirmation that there's a spark before hunting down the EZL.