1997 disco sometimes won't start when hot

[monmendoza]

Good morning,

I wonder if anyone has this problem with their disco. I have a 300tdi disco auto that runs very well but sometimes it won't start when hot. I have already replaced the starter motor with a brand new one but it seems the problem is still existent.

When it won't start, the motor does not turn over. Symptoms is very similar to a the transmission left at drive. but of course its in park.
The dashboard lights do not dim when you turn the starter key and you can't and feel the starter moving at all. If you wait for about 10 minutes
the engine will start one click as though nothing has happened.

BTW my unit does not have an ecu instead it has a manual injection pump.
any inputs would be greatly appreciated. thank you.

[fe11xx]

You'll probably find you have excessive resistance in the starter solenoid circuit. Even though you have replaced the starter (this isn't the problem) the resistance will lie in either the wiring or the key barrel. Instead of tracing all the wiring and switches etc, you can relay the system so your existing solenoid power feed acts as the power for the relay coil. Then the pull in side of the solenoid will get a healthy 12-13v or so from the battery with little resistance.

The reason it does this when hot is that as everything heats up, resistance will increase. If there is already high resistance in the circuit, it simply becomes too much and you don't get anything (hence why the lights dont dim).

Hope this helps