Starter Booster, I hate to revisit this topic, but... Options

[black914]

I have found this topic through a search but my question remains unanswered! I went down to the Queen City yesterday to do a repair on my son's 924S. The trip is essentially 85 miles of 65 miles per hour non-stop driving. When I arrived and rested for about thrity minutes, we decided to go get something to eat first, got in the 914, turned the ignition switch and no turnover. The fuel pump was operating but the starter was not getting the signal. I let it cool for a while, attempted to crank it again and it fired right away. We ran a few errands and made about three stops requiring the engine to be turned off and restarted and I encountered no problems. Went home later in the day around 6:30PM, traveled the miles at 65 steady for about one hour, stopped to get a cola, got back in, attempted to crank it, but again, nothing. Fortunately a good samaritan help me push it off and I got it cranked okay. I got home safely.

I notice that Bosch has encountered this problem before and they have offered a starter booster kit that cures the hot starter problem by boosting the voltage to the starter. My 914 has a remanufactured starter (don't know the age because it was installed by the previous owner).

Would this cure my problem? Apparently it has been a problem in the past or Bosch would not have offered a cure.

Comments?

[914GT]

I had the 'hot start' problem soon after I got my V8 conversion on the road. I already had a new IMI hi-torq starter and a new ignition switch, but one afternoon last summer running errands on a 105 deg day I encountered a 'chattering' starter after having the hot engine off for about 5 minutes. After waiting another 5-10 min. it started normally.

What was happening was once the engine was off and sitting still, the starter motor was getting 'heat soaked' with the heat coming off the exhaust pipe (about 3 inches away) and probably coming off the engine itself. With the engine off there's no air moving around the starter motor so the heat rises and get trapped under there. When I got it home I measured the voltage on the solenoid with the key turned to start position (I had disconnected the battery cable off the starter) and I measured 9 volts. So there was a 3 volt drop in the wires going to and from the ignition switch.

I installed a relay next to the starter solenoid and now always get near full battery voltage on the solenoid. I've never had this problem since. In my opinion, the stock wiring is marginal with not a lot of headroom when the starter gets old, and the resistance in the ignition switch increases with wear. For most parts of the country and a stock 914 maybe the relay is considered a band-aid, but here in the Arizona summer with my V8 car the relay works wonders by eliminating that 3 volt wiring loss.