Starting issue

[Germanblood]

I have and '86 that I rebuilt into a twin plugged 3.5L that has run flawlessly for 12 years but recently it won't turn over.

About a year ago, in mid summer, I drove it, sat for about 4 hrs, went to start it....and "click". I thought oh bummer, battery crapped out. Got a jump, started right up, got it home and replaced the battery.

Next day went to start it with a fresh battery and "click". Only a single click, no chatter. The click is clearly coming from the starter. I have a hard time believing that a brand new, high torque starter would fail after 12 years and 10K miles.

Current draw with ignition on is minimal, so there doesn't appear to be a short.

Before I fight with replacing the starter, I am wondering if the rebuilt alternator I put in at rebuild is the culprit?

Anyone have any ideas before start replacing expensive things? Advice would be welcome.

[Dpmulvan]

Did you check for parasitic draw? I would start there.

[911obgyn]

Check voltage of battery 12.5 resting.
Clean battery terminals and grounds.

[avenbugt]

Originally Posted by 911obgyn

Clean battery terminals and grounds.

That is most likely the problem…

[Dpmulvan]

Originally Posted by Germanblood

I have and '86 that I rebuilt into a twin plugged 3.5L that has run flawlessly for 12 years but recently it won't turn over.

About a year ago, in mid summer, I drove it, sat for about 4 hrs, went to start it....and "click". I thought oh bummer, battery crapped out. Got a jump, started right up, got it home and replaced the battery.

Next day went to start it with a fresh battery and "click". Only a single click, no chatter. The click is clearly coming from the starter. I have a hard time believing that a brand new, high torque starter would fail after 12 years and 10K miles.

Current draw with ignition on is minimal, so there doesn't appear to be a short.

Before I fight with replacing the starter, I am wondering if the rebuilt alternator I put in at rebuild is the culprit?

Anyone have any ideas before start replacing expensive things? Advice would be welcome.

Start by charging your battery then see if car starts.

[ant7]

Ground strap from engine/transmission to chassis, almost a certainty!
Good luck.
Ant.

[Alan L]

Yes, it sounds like you have lost the high load circuit. The 'click' will be the low load circuit from the ignition key side engaging the solenoid. But that kicks over to the high load circuit direct from the battery to the starter. If the terminals at either end are poor, or you have a bad contact on the earth side, you may fail with the starter under high load. The battery earth, plus the earth strap under the car from the trans body to the chassis. It is on the starter side of engine. The other thing you can do is jack the RHS up, jack stands, and try jumping across the solenoid terminals. (You can leave the key in OFF for this). One side has the battery cable (hot). The other side is the delivery from the solenoid to the starter. If you jump those (heavy-ish wire) and it fires the starter then the problem is in the solenoid. It can be fixed.
Make sure the car is out of gear before doing this.
Alan

[Germanblood]

Originally Posted by Dpmulvan

Did you check for parasitic draw? I would start there.

Everything has been ohm'd out and clean connections. Not the issue.

[Germanblood]

Originally Posted by 911obgyn

Check voltage of battery 12.5 resting.
Clean battery terminals and grounds.

Nope...brand new battery and terminals are pefectly clean.

[Germanblood]

Originally Posted by Dpmulvan

Start by charging your battery then see if car starts.

No S sherlock. Done it and even jump packed it on top over full charge. Same single click from them starter. Also, turn the motor over manually. Not seized.

[Germanblood]

Originally Posted by ant7

Ground strap from engine/transmission to chassis, almost a certainty!
Good luck.
Ant.

Been removed, cleaned and ohm'd. Evrything has perfect continuity.

[Germanblood]

Originally Posted by Alan L

Yes, it sounds like you have lost the high load circuit. The 'click' will be the low load circuit from the ignition key side engaging the solenoid. But that kicks over to the high load circuit direct from the battery to the starter. If the terminals at either end are poor, or you have a bad contact on the earth side, you may fail with the starter under high load. The battery earth, plus the earth strap under the car from the trans body to the chassis. It is on the starter side of engine. The other thing you can do is jack the RHS up, jack stands, and try jumping across the solenoid terminals. (You can leave the key in OFF for this). One side has the battery cable (hot). The other side is the delivery from the solenoid to the starter. If you jump those (heavy-ish wire) and it fires the starter then the problem is in the solenoid. It can be fixed.
Make sure the car is out of gear before doing this.
Alan

I have figured this might be a next step. Yes double triple quad check it is out of gear first.

[avenbugt]

Originally Posted by Germanblood

Been removed, cleaned and ohm'd. Evrything has perfect continuity.

In 'normal condition' there can be a connection (0 ohms), but if this connection is not perfect, it can be broken as soon as a load is introduced into the circuit (starter action/startup). Did you also measured the continuity when starting? And how much V gives the battery when starting?
(sorry for the bad English, but I think you will understand)

[Germanblood]

Originally Posted by avenbugt

In 'normal condition' there can be a connection (0 ohms), but if this connection is not perfect, it can be broken as soon as a load is introduced into the circuit (starter action/startup). Did you also measured the continuity when starting? And how much V gives the battery when starting?
(sorry for the bad English, but I think you will understand)

I will try and see.

[ant7]

Another check; when turning the key to start position, measure the actual voltage you have at the starter solenoid wire, [the one that energises the solenoid] it should be at or near battery voltage, if its a few volts lower, then the starter solenoid is not energised enough to throw out the copper bolt inside that connects the high current positive to turn the starter.
Ant.

[ed mayo]

Might need to restake the crimp of the positive cable at the battery. I have seen that lose its tightness.

[911obgyn]

A quick check of ground strap connection is to use one leg of jumper cable and ground engine case to the body, if it starts…
If not then it may be the brand new 12 year old starter.

[spuggy]

to start it with a fresh battery and "click"

You have an electrical connection (so it'll ohm out fine), but the circuit won't provide/support sufficient current to throw out the solenoid. So it just clicks.

As I understand it, once the solenoid engages, it needs to throw out far enough to get the starter circuit (fed by the big fat permanently "hot" wire from the battery) into play.

If the solenoid doesn't get enough current to do that, it just goes "click", and the starter circuit never engages. Some Bosch solenoids gum up when they get too hot, or the grease inside them turns into baked sludge after 40 years - traditional method is to hit them with something to free them off. This doesn't sound like your problem.

You cannot get meaningful results from beeping it out with a continuity tester or checking for a zero/low ohms connection. I also doubt a test light will draw enough current to be useful. Because (for example) a 14-pin engine bay connector with root crops growing on the contacts will pass a continuity test, show a slight volts voltage drop - and only intermittently (when cold and damp) fail to pass enough current to operate the starter. Ask me how I know...

You're always going to get some voltage drop down the yellow wire compared to measured at the battery terminals. But too much is a problem.

Check everything by all means, and refurbish stuff that looks grotty or measures poorly - it won't/can't hurt. Examine the transmission ground strap(s) (some add another for good measure) carefully - harsh exposed environment - and they can deteriorate quickly. Ground point(s) on the body should be bright, clean metal.

Many (some eventually) find this condition to be caused by a poor connection on the infamous "yellow wire" that goes from the ignition switch to the solenoid terminal on the starter - through the firewall plug and the 14-pin connector in the engine bay. Voltage drop on this wire is a symptom of the problem - but not the cause. Which is the inability to carry enough current through the entire circuit. Check this with a clamp ammeter at the solenoid if you like, and work backwards.

Clean/tighten connections, wire condition etc. Note that high-mileage (mine had over 230K miles on it) ignition switch terminal contacts degrade (get burnt away) by internal arcing, given enough starts. Then the electrical portion needs replacing.

At least you've got a sold failure, which should help considerably in diagnosing. Intermittent ones are kind of a bear in comparison.

[Germanblood]

She started! I just bit the bullet and replaced the starter. Charged the battery overnight and turned the key. Rooooommm a zoooom!!!! STARTED RIGHT UP. Happy dance then a drive for the first time in over a year.

I just find it perplexing a starter with 10k on it would fail. Oh well, matters not now. I have my car back. Now just have to fix 5 other minor issues. The joy of owning a 911 continues.

Thanks all for your guidance. Peace and joy for '25

[avenbugt]

If you still have the old starter, I would test it to see what it does without a load