Starter motor / battery question

[slow-lane-Matt]

Anyone come across this...

I have a relative new battery that is fully charged. The bus always starts immediately when cold, and the starter motor turns engine at normal cranking speed.

However - when engine is hot, if I stop and start the starter motor can hardly turn the engine, feels like battery is flat, it really struggles.

If I let it all cool down again, like next morning (without rechanrging battery) - it starts strong again.

Can temperature effect starter motors, or earth connections....?

Does it mean starter motor is on it's way out...

Any suggestions gratefully received

 

[sparkywig]

It's probably high resistance across connections in the 40 year plus wiring loom when warm.
By now somebody should've mentioned a hot start relay, although all this does is mask the symptoms and not cure the problem.
To sort it properly you'll need to check every cable and connection along the ignition circuit, including the ignition switch. And make sure the gearbox earth strap is intact and securely mounted.

 

[slow-lane-Matt]

Thanks Sparkywig

Yeah I follow the logic, and have been considering hot start relay to preserve my ignition switch, but don't really understand how it can be temperature related, the circuit should not be getting that hot

hot start relay - a project for the winter...

 

[sparkywig]

Thanks Sparkywig

Yeah I follow the logic, and have been considering hot start relay to preserve my ignition switch, but don't really understand how it can be temperature related, the circuit should not be getting that hot

hot start relay - a project for the winter...

Engine gets hot, and copper is a good conductor so the heat transfers to a loose connection and causes a high resistance joint.