E30 318i wont start on key, just clicks but will bump start

[pac1982]

any idea what my problem could be?

as the title suggests car will start on a bump but not on key, once running on a bump its a bit sketchy for a few moments and battery light is on but then runs just fine and will start up on the key for a short time after a bump start.

battery seems to have lots of power as the windows are not going slow and lights are bright.

when I try to start it from cold on the key I just get a single "click" and every now and then a slight crank of the engine.

I'm guessing starter motor is faulty or the battery is not quite giving out enough power to turn the starter.

any other ideas to help my diagnosis?

[Speedtouch]

Could be a failing starter motor solenoid, rather than the motor itself.

Try using a jump lead to go direct from battery +12V to the starter motor's positive terminal (thus bypassing both the ignition switch and solenoid). If it spins the engine over OK, you either have a duff solenoid or possibly, failing ignition switch.

[pac1982]

Could be a failing starter motor solenoid, rather than the motor itself.

Try using a jump lead to go direct from battery +12V to the starter motor's positive terminal (thus bypassing both the ignition switch and solenoid). If it spins the engine over OK, you either have a duff solenoid or possibly, failing ignition switch.

thanks i'll take a look, do you think it could be a fault with my immobilizer? or would i not be able to bump start the car if the immobilizer was stuck on

[Speedtouch]

Could be, but also, and before you do anything else, check that the engine-to-body earth strap is in good condition and bolted up nice and tight.

[Grrrmachine]

battery seems to have lots of power as the windows are not going slow and lights are bright.

The amount of power needed to make a bulb glow is pathetic compared to the juice needed to power a starter motor enough to spin round an engine. To rule out the battery, which is the main culprit, you need to get it load tested or replace it with a known good one.

[Brianmoooore]

Try using a jump lead to go direct from battery +12V to the starter motor's positive terminal (thus bypassing both the ignition switch and solenoid). If it spins the engine over OK, you either have a duff solenoid or possibly, failing ignition switch.

Moggies may have inertia starter motors, but E30s are a bit more advanced! Connecting a lead as you say may spin the starter motor over (at speeds which aren't good for it), but won't engage the pinion and turn the engine.

[Brianmoooore]

The amount of power needed to make a bulb glow is pathetic compared to the juice needed to power a starter motor enough to spin round an engine.

Very true, but the trick is to see if the bulb stays bright when you try to start the engine. If the bulbs go out, or nearly so, when the starter load goes on, then the battery is low.

[Brianmoooore]

Could be, but also, and before you do anything else, check that the engine-to-body earth strap is in good condition and bolted up nice and tight.

Check all the joints/connections in the starter to battery circuit (the thick wires) for heat after the starter motor has run. Poor connections can produce a lot of heat, and give their location away.

[Billwill]

Do all of the above tips such as checking the earth straps.

The Black/Yellow wire that comes straight from the ignition switch onto the solenoid may not be getting a decent +12 volts on it when you turn the key so you just get a feeble click on the solenoid.

This could be caused by a worn-out ignition switch...quite common...or an immobilisor problem.

Take a lead direct from the positive of the battery direct to where this Black/Yellow wire connects...or jumper this connector direct to the thick positive cable next to it. If it turns over nicely now then your ignition switch or immobilisor is bad.

I have my ignition switch actuate a seperate large relay which in turn activates the solenoid...due to the ignition switch wearing out yet again!

[B7]

Have you tried a new battery?

Purely the fact it won't start initially but if you bump it, let it run a while then try again and it starts, says to me tha batteries not holding its charge and the short burst of power from the alternators gives the battery a bit of life?

As above, lights and windows will work on a slightly discharged battery but try and start it and it'll fail to turn it over.

Sounds a bit simple but surely start with the basics?

[Speedtouch]

any idea what my problem could be?

as the title suggests car will start on a bump but not on key, once running on a bump its a bit sketchy for a few moments and battery light is on...

Battery light on indicates that your alternator isn't charging - the battery light should go out very shortly after the engine fires up.

[pac1982]

right thanks for all the help folks, I have disconnected my immobilizer to rule that out, tried direct power to the starter but nothing.

also tried a known good battery still with no joy, so I think its down to my ignition switch or starter motor.

Before I disconnected my alarm & immobilizer it had a remote start function but it would not start using this either would the remote start bypass my ignition switch hence ruling out faulty ignition switch and leaving me with the likely culprit being the starter motor?

[Speedtouch]

Could be, although in your first post you said that operating the ignition switch would produce a click, suggesting it works OK.

Sounds like it could well be a dodgy starter motor. Have you tried giving it a clout with a club hammer?

Alternatively, stick it in 2nd gear and rock the car back and forth a few times, to rule out a stuck starter inertia.

[pac1982]

Could be, although in your first post you said that operating the ignition switch would produce a click, suggesting it works OK.

Sounds like it could well be a dodgy starter motor. Have you tried giving it a clout with a club hammer?

Alternatively, stick it in 2nd gear and rock the car back and forth a few times, to rule out a stuck starter inertia.

tried whacking it with my largest socket wrench with no joy and did try the rocking thing but in first, I shall try it in second if that's the correct way to do it.

Looking at it it seems E30 starter motors are cheaper than remember them at around £100 from ECP and although not ideal I dont mind replacing ageing parts with nice shiny new ones although I would like to find out 100% it was my starter before spunking 100 quid of my hard earned.

Any way for me to confirm its the starter?

[Speedtouch]

You could try removing it and hook it up to a good battery, stand on the motor to prevent it moving then bridge the contact to the solenoid. It should spin up nicely.

It may just need a bit of cleaning or lubrication with graphite powder (not oil or grease).