Overheated Ignition switch

[Mike C50]

Hi All,  Yesterday, I was running a 72 in the driveway.  I got called away and when I returned 15 minutes later the engine was off.  It was a hot day here about 90F. When I got into the car the rubber on the key was hot and plyable. To make a long story short the key turns freely in the cylinder with no resisatance what so ever.  It's like a complete empty shell it spins but does not crank or turn anything.  I have never had an overheat problem before but I have not been running the car as much as I would like.  Any ideas where so much heat would come from.  I have no idea yet if there is any engine damage.  Has anything like this happened to anyone?

[RobH]

The  most likely source of heat is a bad electrical connection passing a high current Mike.  I expect what has happened is the plastic switch mechanism has melted which is why you feel no resistance (pun?).  The electrical connection was broken and the engine stopped. because it had no fuel or ignition. 

Depending on the model of ignition switch you have, it might be a simple matter to fit a new mechanism - not the lock, just the switch wafer. Before you do though, you need to check whether there is a short-circuit somewhere or whether the fuel pump or ignition are drawing excess current as that could be the main contributory factor (those circuits are un-fused as standard).  Also the heat may have damaged insulation on the wires to the switch - very important to check that too. 

What make of fuel pump do you have? Is it fed via a relay or direct from the ignition switch? 

 

 

Edited June 27, 2022 by RobH

[Mike C50]

Thanks Rob I have some detective work to do. I have the Lucas fuel pump. It looks like the only way to get at the ignition key switch is to pull the whole thing out from behind the dash.  Not my favorite spot to work in.  Cheers