Which Sterter Solenoid?, Looking to remedy the infamous hot-start issue Options

[JDW914]

Hi all! I recently took my first long road trip in my 914 (700 mi round trip out to Peoria, IL to finally pick up a replacement windshield) and while the car performed beautifully, I had my first encounter with what I've learned is the "infamous hot-start issue." Happily I was caravanning and, when unable to find a clear reason as to the car's failing to start after a pit stop for lunch, we tried jumping it, assuming the battery had gone bad, which resulted in enough current to pop the solenoid and start it up. This was necessary a few times during the trip. While it has never caused me trouble before (I've been driving the car pretty regularly for 2 years since its restoration has been "finished") I'd prefer to remove the issue so that it doesn't come back to bite me, especially now that the car has proven itself as such a good road-tripper.

Now in my research since encountering the issue, I've found much documentation of the issue and its solutions, in particular a Ford starter solenoid or a Bosch hot start relay kit. I'd like to go about it with the replacement starter solenoid as this seems a simple and straight-forward enough change-out, however, I've not been able to determine what solenoid it is in particular that will fit into an old VW starter motor. Is there a particular part number or set of models/years that use it, or does Ford have enough standardisation that any old solenoid will work?

Thanks for any enlightenment you can provide!

[Tom_T]

You may have one or more of a few things going on there.

1. The infamous hot start problem due to fuel vapor lock problem on 70-74 914s - if your fuel pump is in the engine bay, then it gets so hot that vapor bubbles form in the lines whenever you stop & it gets no fuel. The best solution which Porsche did a service bulletin for, has the fuel pump relocated to up behind the steering rack below the fuel tank (in 75-76 models they move the fuel pump up front for that reason).

It's not a running problem in hot weather as long as you don't shut down, since the fuel running thru the pump cools it enough to prevent vapor forming (as soon as you shut down the hot fuel pump forms the vapor), so you could leave it running for a quick pee stop with someone else in the car.

A temporary fix is one of those heat blankets that some of the Porsche supply houses sell for it, but the fuel lines can still bubble up & cause the pump to cavitate.

So you really want a fuel pump relocation kit like AA & maybe others sell - or make up your own looking at the kit - then move the pump.

The "in the field" solution is to let it sit & go have a milkshake or something, until the fuel cools down enough for the bubble to turn back to liquid, & you could take water up under there to pour on the pump to cool it down, but I wouldn't on these rust prone cars - plus it's very tight & a very hot engine, tins, etc.

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2. The ole "flat spot" on the starter's rotor problem - the Bosch starters on all air cooled & some water cooled VW's & Porsches get hot & develop a bad contact area or "flat spot" on them & when you stop for food/lav breaks, then they can refuse to start/turn at all.

The solution is a new starter - OEM Bosch or upgrade to a hi-torque aftermarket one (several out there).

The old school "in the field" solution is to reach or get under there with a ball peen hammer or wrench or something & tap the starter casing hard-ish (NOT the solenoid) while someone else in the car turns the key to start it. It may take 2-4+ tries, but that usually breaks it loose to get the starter to turn. It only works if someone else is turning the key to start.

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3. Related to the above, is the solenoid sticking due to the heat expanding the mechanism, so it cannot push the starter gear into the engine's ring? gear (spacing on the gear name now) to start it - as discussed by others above.

The fixes are the high torque starter, hot start relay kit &/or running a new set of direct wiring lines to the battery with a protective relay yourself - since the old wiring as it ages has more resistance & gets less "juice" to the starter (my mechanic recently did the latter on our `88 Westy waterboxer for tough hot starts on it). I've never heard of the Ford solenoid thing, but maybe that works too??

The old school "in the field" solution is to try the starter tapping above &/or a LIGHT tap with a screwdriver on the solenoid if the other doesn't work.

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So I guess that's my contribution to the annual run of spring/summer hot start problem posts on here! (IMG:style_emoticons/default/biggrin.gif)

PS - Thanx Mark - I haven't come across that Ford relay / solenoid solution before!

Happy 4th & Thanx to those who served! (IMG:style_emoticons/default/flag.gif)
Tom
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