912 starter problems

[NICHOLASJCRAIG]

Any ideas would help.

So, the 912 has decided to pick the exact day I got my RWC for the club permit to stop working.

When I try to start the car I get nothing from the starter, not even a click from the solenoid. There's a solid 12.5V getting to the starter that doesn't budge when I turn the ignition, however the instruments die when I try to turn it over.

All the electrics/lights/gauges work fine normally. This is the first time it has ever shown signs of not even turning over.

I'm guessing the issue lies with the solenoid, but could there be an issue with the ignition or wiring?

N

[Classic]

69 has a relay at the end of the ignition switch loom........you can find it up behind the clock, with the flasher relay.

I don't know if yours has the same, I'm not familure with SWB electrics.

[Harry]

Hi Nick,

Did you give the starter / solenoid a tap with a hammer? Give it whack and if it starts it should help point you in the right direction.


Cheers,

Harry.

[Merv]

It could be anything between the ignition switch and the starter connection with the flywheel ring. The rubber hammer hit approach is always a good idea first.

No grinding noises before this event, that might indicate pinion failure or loss of teeth in the geared drive on the flywheel?

Most likely culprit is the solenoid on the starter OR a poor/degraded Ground connection. A check by using a new wire, externally, direct from starter switch (I think yellow wire, but check) to the +ve on the solenoid, should tell you some of the story. There are quite a few threads on this.

Starters are pretty easy to move and bench test as well, if needed. Last, does the battery really have the cranking amps?

[NICHOLASJCRAIG]

Thanks guys. Does anyone have any photos/terminal layouts of the starter solenoid?

Battery is less than 6mo old.

After doing some investigating it appears the PO installed a SPDT relay in the ignition circuit under the dash - probably as a security 'feature' with a really dodgy 85 (or 86) ground connection. The 30 is spliced into another circuit, and the 87 is into the original yellow ignition wire. That was potentially one issue sorted.

There is also, what appears to be another solenoid, in the ignition circuit. It's identical to this:


Can anyone tell me what it's used for and if it's usefull to keep? I've confirmed that the control wire is the ignition wire, however, one of the 'power' wires (spade connector) is floating loose about the starter solenoid. I can't see which spade connector on the back of the starter solenoid it's meant to be connect to - does anyone have any photos/terminal layout's to help?

Thanks,
N

[Merv]

Strange. That looks like an older model Ford solenoid, and why 2?

Is this what you want?

[NICHOLASJCRAIG]

Thanks Merv - not quite what I was after, but interesting nonetheless. I eventually pieced things together and guestimated the terminal arrangement and relay/solenoid/solenoid/starter mix. Either way, it's all fixed now and starting as reliably as before.

I found this on the pelican parts forum:

http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/617157-hot-wont-start.html

Not sure if it's a good thing, but from what I can tell by using the ford solenoid, it just increases the power to the starter solenoid. Seems to be a way of covering up the slow degradation of the starter solenoid contacts, or possibly reducing current flow through the ignition switch.

Now... to decide what to do to the ignition circuit - leave as is; modify slightly; or change it back to original...

N

[Merv]

Live and learn .... "More is better" is a principle that can be applied to solenoids too. Good that its starting now Nic. Can you pull the starter motor, put on a new solenoid (assuming it is attached to the starter on yours) and a new earth connection?

[Jeff Eelkema]

Even though it is starting the fact the gauges went nuts suggest a bad earth somewhere. Might pay to clean and tighten every earth you can find including the main lead between chassis and trans/engine.

[NICHOLASJCRAIG]

Even though it is starting the fact the gauges went nuts suggest a bad earth somewhere. Might pay to clean and tighten every earth you can find including the main lead between chassis and trans/engine.

My guess is that the SPDT 'security' relay is tapped into the instrument cluster supply or similar. Turning the starter/ignition circuit drains all current/voltage from the instrument cluster into the ford solenoid.

[Classic]

Nice fault finding. After market add ons can be a nightmare.