Electrical

Starter Wont Engage When Hot

After several bouts of having the starter refuse to engage last year, only when hot (problem always went away after a few minutes of waiting), I had the starter replaced and everything was fine since then. However, just this evening, after going to a local restaurant for takeout, the starter refused to engage once more!!!!! How embarrassing. Had to eat my takeout in the restaurant ...
Anyway, the tow guy shows up, fiddles with the auto shifter and lights, and of course it won't start. Then we push it back out of the parking space, and then roll it forward to the receiver on the tow truck. Guy gets in to put it in park, tries the ignition, and voila, it starts up!!! More embarassment.

#1
I had a similar problem with my 81, It turned out to be just cleaning the wire terminals. be sure to do the one at the battery also.
*Ron Triano; 1981 928 Metallic Gold

#2
Whenever an elderly 928 fails to activate its starter when hot I immediately suspect the wiring to the starter solonoid. This is rather heavy multistrand wire which accumulates corrosion over a period of time. The electrical resistance of corrosion skyrockets when heated, hence the elusive and frustrating failure of the car to crank when in public circumstances like gas stations, quick stops, etc.
The solution is to replace that part of the wiring harness, a fairly difficult job, or bypass it using a large relay. On several occasions I have used a glow plug relay and heavy wire, using the starter solonoid wire to activate the relay, and "relaying" the heavy wire from that large positive terminal on the passenger side of the engine compartment directly to the solonoid. While this may seem inelegant, it is cheap and effective.
*Dave Cooley