Overheating protection on 1989 760 turbo wagon

[JohnR]

A couple of times this spring I have had the wagon not start after it has been stopped -- the starter will not activate. Both times the weather has been warm enough to have the air conditioner on. It appears to be quite hot under the hood, but the temperature gauge registers normal, and the radiator is relatively new, as is the heater core. After letting it cool off for about 1/2 hour to 1 hour it starts just fine. Is there a heat protection device in the starter which might be out of synch? Or is such a protection device located somewhere else? Thanks for any ideas.

[billofdurham]

I have not heard of a heat protection device on the starter of any car and can find no reference to one in the many Volvo books I have.

It would appear to be a heat related electrical problem. When the starter does not activate do any of the other electrics go out?

At this time all I can suggest is a general check of all connections in the starter circuit, especially battery leads and solenoid leads. Pay special attention to the earth (ground) point on the body and the earth strap from the engine to the body.

As a further check, if it should happen again and you have a voltmeter, have someone turn the ignition key to the crank position and measure the voltage at the spade terminal of the starter solenoid. The reading should be at least 8 volts. If it is not at least 8V check the voltage at the ignition switch. If the voltage at the switch is at least 8V check the wiring between the ignition switch and the solenoid. If it is not 8V, replace the ignition switch.

If on the check at the solenoid spade terminal the voltage is at least 8V measure the voltage at the starter terminal of the solenoid. If the reading is at least 8V repair or replace the starter. If the reading is less than 8V replace the solenoid.

The above checks on the solenoid and ignition switch should only be done after the connections have been checked and the battery is fully charged.

If the vehicle has an auto box also check the Park/Neutral switch.

Bill.

[sseir39]

Bill has stated your areas to check. I emphasize the battery cables. In my experience corrosion builds up internally and with heat the resistance is so high the juice can't flow to the starter. Your car is old and things go south, especially anything electrical.

[JohnR]

Many thanks for your suggestions -- they make sense given the age, etc.

It is a puzzler, but I will follow-up on the cables: the starter, and electrics never miss a beat -- usually. And no other electricals are affected with this 'over-heating' scenario. Auto interlock and electricals is ok.