Intermittent starting issues (hot and cold starts) Options

[DC_neun_vierzehn]

I recently started having starting issues.

Here's the recent history ...

I had zero starting issues on the car for nearly 2 years of ownership (1973 2.0 w/ a starter relay).

Then, we dropped the motor and sent it off for a 2056 rebuild last year (and Dr. Evil rebuilt my trans at the same time).

When a friend and 914 world regular helped me do the reinstall, the key in ignition switch would not start the car (the car was sitting in storage for about a year waiting for the motor and trans rebuilds). As a temporary solution, we put a remote starter in the engine bay (alligator clips to the starter) and that solved the non-starting problem. Thus, we assumed the starter switch likely needed replaced. I put that on my project list.

I used the remote starter for a few months (and ordered a replacement ignition switch). Before installing the replacement switch, I decided to put the key in to confirm the switch was bad ... well ... it worked! Thus, I started using the key to start the car for the next couple of months without any issues.

Then one day the key in the ignition would not work. It was a cold start. Car was sitting for over a day. So I tried the remote starter ... same thing ... even the remote starter wouldn't work.

So I jacked the car up and put it on stands to inspect starter from under the car. No loose wires, not corrosion, the alligator clamps for the remote starter were still where they should be. I also looked at the starter connections that go to the battery in the engine bay from above ... all looked fine there too. Nothing loose, no corrosion, etc.

So I lower car and I try starting it with the key ... and it worked. WTH? I turned it off. Tried the remote starter. That worked as well.

For the next week or so the key worked.

Then yesterday, neither would work again. This time it was a hot start. I had been driving for about 45 minutes so it was fully warmed up.

So the intermittent starting issues are happening on cold AND warm starts.

So again, I jacked the car up ... looked for anything suspect around the starter ... looked in engine bay for anything loose ... didn't see anything. Then lowered the car and tried the key ... it worked and so did the remote starter.

It's frustrating and I don't want to get stranded somewhere (it's very flat where I live and I can't park on hills to rely on popping the clutch to start the car if the ignition isn't working).

Any ideas could be causing the intermittent issues?

[wonkipop]

i've got a theory on the old hot start issue with 914s.
and its not to point at the solonoid (its quality) as where the blame is.

but i guess its not the problem here as this one is doing it cold.

my theory is the same as the old vapor lock fuel pump problem.
same source for the probkem.

the fan shroud duct on the type 4 engine is a magnesium alloy.
the gearbox casing is also magnesium alloy.
but the engine is a combination of alumium alloy(crankcase/heads) and steel.

after you shut the car down after a long run or even a run where it gets decently hot.
heat from the engine proper naturally flows via conduction to the magnesium pieces.
in particular the fan shroud casting and the gearbox.
the engine itself cools down (in part) by losing heat to these parts.
which radiate that heat as they cool down.

and the type 4 engine and even the porsche gearbox were not designed with either location in the car (mid engine) in their original design applications (rear engined).

914 underbody cavity or recess from firewall to rear bumper is a beautifully designed heat trap when the car is sitting still and not running after a good longish run.
one big bubble of hot air.

which makes it harder for the fan shroud and gearbox to lose that heat they are radiating after hot shut down.

the primary victims of this are
1) the fuel pump
2) the starter solonoid.

i never had problems with the starter (solonoid) on my old type 3 variant.
pretty much the same bosch starter as on the 914. nor the fuel pump.
the engine hung out the back and could easily lose heat after hot shutdown.
it just escaped as heated air from out the sides of the rear of the car.

i'm guessing much the same for 911s as i have never heard of any persistant hot start problems that 911s of the same vintage having.

mine will do the hot start no start under very specific circumstances.
good hot run. stop the car. leave it for more than 1/2 an hour and less than about 1/1.5 hours. no start. no click even. get under gently tap the body of the start motor and it will start. if left to cool down for longer problem never appears. if started in under approx 1/2 hour from shut down it will start.

its been doing it for 35 years. and i replaced the entire starter motor 30 years ago when bosch were not crap. nothing changed.

i don't blame the components, i blame flaws in the original design of the car.
charming flaws i put up with. (IMG:style_emoticons/default/biggrin.gif)

i've never had the vapor lock problem with the fuel pump.
its still in stock 1974 position.
i put that down to it being an L jet maybe. runs at higher pressure on cranking.
dunno.

if you don't believe my theory on heat conduction flow from alum/steel to magnesium next tie you take your car for a run at the end before you shut down. ppen the engine lid and put your hand on the magnesium fan casting. you will find its cool to the touch while the engine is running. cooling air keeps it cool. shut it down then come back 20 minutes later. touch it. be careful. its very hot.

i have done the same with the gearbox. initially it will be coolish to the touch.
come back 20 minutes later and touch it. noticeably hotter by a lot.

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present problem discussed here could be a combo of the inherent problem built in to all stock 914s as well as another intermintent electrical problem due to aged wiring in the ignition circuit or the ignition switch itself or a dirty (bad) ground.

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