Starter solenoid single click?
 

I get a single click from my starter solenoid, no cranking of the starter. Good battery. Does this indicate bad starter, bad solenoid, engagement issue or it doesn't matter just replace the entire starter and solenoid unit? '79 911 SC.

Sounds like bad solenoid. Normally the solenoid kicks the pinion out far enough to engage the starter ring teeth and far enough to close the contacts that power the starter motor. Sounds like you're getting the former but not the latter.

One test is to have someone hold the key in the start position while you CAREFULLY whack the starter body with something heavy. That can jolt the solenoid enough to make contact and run the starter.

Let us know if you get the solenoid replaced. I had a similar problem a few years ago and could not find a shop that would rebuild the starter. They were too intent on selling a new starter.

The easy route is to exchange everything with $$. However, that method also ignores relatively easy diagnosis (loose/corroded electrical connections; including a bad ground connection - excessive voltage drop). In addition, a "good" battery could be at fault. Depends on how that condition is derived.

The solenoid or the motor itself could be the cause. I'd start with removing the starter unit, then bench test it. If you don't want to delve into further diagnosis and repair, an option is to purchase a working used, rebuilt or new unit. In any case, bench test before installing.

Sherwood

+1 ^

I've seen old solenoids just get clogged with dirt and grease. They only produced a single click. Once the starter is out, it's pretty easy to detach and clean a solenoid.

I found it a pain to remove and install the starter on a 911. You need a good selection of socket extensions and a strong light, because everything is black on black from road dirt and grease. The last time(s) I've done it, I used a partial engine drop and just went in over the top.

Last year I replaced the solenoid on the starter on my 1978SC. Cost was £25 (UK). Hardest part is removing the starter. I did it by lying underneath with my feet sticking out the back. You can reach round then to the top barrel nut. You will need a longish 10mm allen socket.

Sounds like you checked the basics, so good start. Next easy thing to do before taking stuff apart - as 911pcars suggested, check the connections on your starter and also the ground strap which is usually between the trans and the chassis. Bad connections in any of those spots can cause what you describe.

If you're getting a "click" that means the starter solenoid is working. The problem might be that the solenoid isn't travelling far enough to complete the circuit and engage the starter motor... or the motor crapped out. Put it on jack stands and jumper the starter motor.

There can sometimes be too much resistance in the wiring, reducing voltage and/or current to the starter. The installation of a relay at the starter is a good idea.

Every year or so when I get a CLICK only, I need to remove the battery leads, clean up with the inside of the terminal cables, outside of the battery terminals with steel wool, and it will start right up.

Even when they look pretty good, there must be some corrosion. Highly recommend you start here since it's super easy to do and has worked for me at least 2 times.

This.
In my case it was the ground strap between trans. and chassis.

As others have said, the clicking sound more than likely is the solenoid trying to energize the starter. Several causes for no cranking:

1. Check your battery voltage to make sure it is fully charged or put it on charge overnight to be sure. If the battery is bad the voltage will drop below 12 volts when trying to start.
2. Test Starter motor, (transmission in neutral) apply battery voltage to the starter motor directly to see if it cranks this bypasses the solenoid contacts. If it doesn’t crank pull starter and rebuild/replace.
3. If the starter cranked over, next, apply battery voltage and ground directly to the solenoid to energize starter motor. If it cranks you have an issue with wiring possibly a poor ground. If it doesn’t crank pull starter, repair/replace solenoid.

The starter/solenoid may have worn brushes, solenoid contacts have arched and built up a high resistance on the starter/solenoid contacts.

As a DIYer I have rebuilt several starter/solenoids from my cars over the last 50 years and besides getting greasy and a few cuts it is not difficult and it will save you $$$.

Triple check the battery. Including bringing it in to a FLAPS for a load test.

I had an ~18 month old, dealer installed, Porsche branded battery that I was *certain* was good. Guess what was causing my single click issue?...

The ~18 month old, dealer installed, Porsche branded battery.

Jus'sayin'.

Grounds.....I have a tee shirt that says that.

I had the same problem and it went away by changing the ground cable at the battery and transmission.

Lorne M

David23, did you figure out the problem?

So far the battery and grounds check out ok, Haven't been able to get cars moved etc to make room to jack it up enough to test all the leads. I am now getting inclined to simply buy the new High Torque lightweight starter and consider it an upgrade. :)

I'm shuffling several other projects on some of the other cars, so I just have to make more time and room!!!!