This is a fairly common question on this forum. Demarne, I see you asked this back in September and I'm sorry to hear you are still having problems after all this time. [
] My answer then was as follows:-
"
It could be any one of a number of issues including poor/corroded electrical connection, bad earth, faulty battery (it's possible for it to supply current but fail under load), faulty starter, faulty clutch switch etc. etc.
As you can see it's not easy to diagnose from afar.
I'd start with checking the connections, ideally use a multi-meter. Then get the battery tested under load, then the clutch switch, then starter motor. Hopefully that will solve the problem. If not I would get your OPC or a good Indy onto it"
You have requested a more detailed explanation of the starter system so here goes.
Starter motor
A starter is an electric motor that turns over or "cranks" the engine to start it. It consists of a powerful DC electric motor and the starter solenoid. Inside the starter motor there are electric windings (coils) attached to the starter motor housing and the armature (the rotating part), connecting through the carbon brushes in series with the windings. On the front end of the armature, there is a small gear attached to the armature through an overrunning clutch.
Starter solenoid
The starter solenoid is basically a powerful electric relay and when activated, it closes the electric circuit, sending battery power to the starter motor. At the same time, the starter solenoid pushes the starter gear forward to mesh with the engine flywheel. The solenoid has one small connector for the control wire.
Battery cables
The starter motor itself requires very high current to crank the engine and is therefore connected directly to the battery via a thick cable. This is often connected to the alternator for convenience. The negative (ground) cable connects the "-" battery terminal to the engine cylinder block close to the starter via the chassis. The positive cable connects the "+" battery terminal to the starter solenoid.
How a starting system works:
Turning the ignition key to the Start position, provides battery voltage through the starter control circuit and activates the starter solenoid. This energizes the starter motor and the solenoid pushes the starter gear forward to mesh it with the engine flywheel. The flywheel is attached to the engine crankshaft and as the starter motor spins, it turns the engine crankshaft allowing the engine to start.
Neutral safety switch
For safety reasons, the starter motor can only be operated when the clutch pedal is depressed or, in the case of automatic transmission or PDK when the lever in Park or Neutral positions. To accomplish this, there is a Neutral Safety Switch installed at the clutch pedal. In the case of auto or PDK this is a transmission range sensor that tells the powertrain computer which position (P R N D) the transmission is in. When the clutch pedal is not depressed or the automatic transmission is not in Park or Neutral, the neutral safety switch is open and the starter control circuit is disconnected.
Starting system problems
It's common at this time of year for a battery to fail, due to the extra loads placed upon it from heaters, fans, defrosters etc. Sometimes an electrical component is left on or has a defect causing parasitic current draw that drains the battery. Occasionally an old battery can just die one day, with no warning.
If the battery is low on charge, it won't have enough power for the starter motor to turn over the engine. If the battery is low on charge, you will probably hear a clicking noise or the starter may turn very slowly when attempting to start the engine. Poor connection at the cable terminals can cause the starter not to work or run very slowly. Often the battery terminals or the ground cable connection get corroded or frayed, this sets up resistance in the circuit and the starter can't get sufficient current.
The starter motor can fail. Sometimes the carbon brushes or some other parts inside the starter motor wear out and the starter motor stops working. Sometimes the starter gear for some reason won't mesh properly with the engine flywheel. This may cause a very loud metal grinding or screeching sound when attempting to start the car. If the starter motor is defective, it will have to be rebuilt or replaced.
An ignition switch can also fail. The contact points inside the ignition switch wear out, so when you turn the ignition switch to the "Start" position, no electric current is going through the starter control circuit to activate the starter solenoid. If jiggling the key in the ignition helps start the car, it's possible that the ignition switch is defective.
A neutral safety switch also can fail or become maladjusted.
Sometimes there's a really obscure reason for poor starting. For example, following a spate of prematurely failing motors, the fault was eventually diagnosed as a warped bellhousing! This was leading to misalignment of the starter gear and the flywheel ring gear, necessitating machining the bellhousing mating face in order to true it up.
SRD - As regards your problem, since the solenoid appears the operating, it's safe to assume it is a high current or starter motor problem. Firstly, check your battery has a good charge, then check the high current connections down to the starter for corrosion and tightness. Similarly check the engine earth strap for the same. If you suspect this strap is faulty, try using a jump lead direct from the battery negative pole to a convenient point on the engine. If this improves matters replace or use an additional earth strap.
Finally if all this fails to improve things, then the motor itself is the culprit. [
] Remove it and get it tested. There are firms that will repair it or your OPC or Indy will replace it.
You do not give your mileage, but starter motor failure appears fairly common on Gen 1 911's.
Phew...................... hope that covers everything! [8|]
Regards,
Clive.
