BMW wont start

[wjwren]

I've got a 645, but apparently after looking on the net this affects most BMW models. The car is warm (normal operating temperature) and I was in a line of traffic that was standstill so turned the engine off. Come to restart and nothing - sat nav etc works but it wont crank or start - nothing. Ive had this fault now 4 or 5 times. I cure it by either leaving it or found using a jump start off another car. The last time it happened AA chap said the battery was fine.

Anyone else had this issue and found a cure? I am reluctant to send it to a garage as the fault wont be there and they will just be changing things in the hope of fixing it.

[Elliot2000]

Might be worth having a look in the boot- there is a power cable under boot floor panels that corrodes and gets hot and causes a poor connection from the battery to the starter- doesn't take long to check - pull the boot floor panels up and then lift the little plastic cover up where the cable ends and see if it looks rusty or corroded , also check ur battery terminals are tight

Connection looks like this-
https://encrypted-tbn0.gstatic.com/images?q=tbn:AN...

Edited by Elliot2000 on Thursday 10th August 20:38

[SebringMan]

What year is it? Is it an SMG? If so it could be a number of things including:

-Brake pedal switch
-SMG pump relay failure
-Pump/motor failure

The brake pedal issue could affect the autos but I don't think they need the brake pedal to be pressed in so as to start.

How long have you had it?

[wjwren]

Not SMG but is an auto. The brake pedal has to be pressed to start it. Its a 2004 ive had it about 3 years and had this issue about 6 times. The previous owner said he had it once.

[Sheepshanks]

wjwren said:

...wont crank...

Random thought - immobiliser?

I've had curious no-cranking on a few cars in my life and getting out, locking the car and then trying again from scratch has sorted it.

[wjwren]

I tried that kept locking it and unlocking it. It's highly annoying as I dont want to sell it but when it happens im cursing the thing like hell!!

[Collectingbrass]

Is the engine cranking at all? I had a similar problem at Christmas this year with the same age model, and it was the starter motor earth lead. The part is a special, £150 or so from BMW Germany plus fitting by your indie in 2 hrs.

Make sure you keep the battery charged up too, and in good condition. The cars and batteries don't like short journeys, nor I suspect sitting in traffic either, and a low or poor battery can set off all sorts of random error messages that can affect starting.

[wjwren]

i checked the battery and it was near enough 100%. Though the colour checker on it is black? Are these very reliable?

[wjwren]

Just read this which is interesting. I do a lot of short journeys.

http://www.bimmerfest.com/forums/showthread.php?t=...

[SebringMan]

One way to rule out the brake pedal switch is to see if the brake lights are illuminated when the ignition (Ignition postion II) is on.

[Collectingbrass]

wjwren said:

i checked the battery and it was near enough 100%. Though the colour checker on it is black? Are these very reliable?

The sight glasses are at least good enough to say there's a problem that needs further investigation.

When you say the battery was 100% what do you mean? There's 3 points you should be looking at the voltage; cold & everything off inc NAV / idrive asleep, cranking / starting and engine running (& charging) under load. This thread has the details but you should be seeing around 12.5v, 9.6v and 14v on a healthy system

http://www.bimmerfest.com/forums/showthread.php?t=...

I would get a cheap OBD bluetooth reader (https://www.amazon.co.uk/d/ijq/Torque-Pro-Elm-327-Android-OBD-Bluetooth/B01AC7I7BO/ref=sr_1_1?ie=UTF8&qid=1502519491&sr=8-1&keywords=odb2+bluetooth) and the Torque app & see what the ECU thinks the voltage is. You will also be able to see whether there are any basic error codes - but it wont give you everything

If the battery is over 5 years old (it should have a manufacture date on it somewhere on the top) I would change it out. That said, I've had starter motor problems on two cars that gave your symptoms & I initially thought were due to an old battery and changing the battery fixed neither.

Oh, and dont let anyone tell you it's the starter itself without checking everything else. That's exhaust manifold off and a big bill. I was quoted £900 labour plus £250 for the starter motor. Fortunately I took it somewhere else who did a better diagnostic job.

[wjwren]

Elliot2000 said:

Might be worth having a look in the boot- there is a power cable under boot floor panels that corrodes and gets hot and causes a poor connection from the battery to the starter- doesn't take long to check - pull the boot floor panels up and then lift the little plastic cover up where the cable ends and see if it looks rusty or corroded , also check ur battery terminals are tight

Connection looks like this-
https://encrypted-tbn0.gstatic.com/images?q=tbn:AN...

Edited by Elliot2000 on Thursday 10th August 20:38

Il take a look at this as it only ever happens when the engine is hot.

[wjwren]

Collectingbrass said:

The sight glasses are at least good enough to say there's a problem that needs further investigation.

When you say the battery was 100% what do you mean? There's 3 points you should be looking at the voltage; cold & everything off inc NAV / idrive asleep, cranking / starting and engine running (& charging) under load. This thread has the details but you should be seeing around 12.5v, 9.6v and 14v on a healthy system

http://www.bimmerfest.com/forums/showthread.php?t=...

I would get a cheap OBD bluetooth reader (https://www.amazon.co.uk/d/ijq/Torque-Pro-Elm-327-Android-OBD-Bluetooth/B01AC7I7BO/ref=sr_1_1?ie=UTF8&qid=1502519491&sr=8-1&keywords=odb2+bluetooth) and the Torque app & see what the ECU thinks the voltage is. You will also be able to see whether there are any basic error codes - but it wont give you everything

If the battery is over 5 years old (it should have a manufacture date on it somewhere on the top) I would change it out. That said, I've had starter motor problems on two cars that gave your symptoms & I initially thought were due to an old battery and changing the battery fixed neither.

Oh, and dont let anyone tell you it's the starter itself without checking everything else. That's exhaust manifold off and a big bill. I was quoted £900 labour plus £250 for the starter motor. Fortunately I took it somewhere else who did a better diagnostic job.

I had an RAC battery charger and hooked it up and it read the battery was 98% full.

[padhinbed]

Could it be the cam or crank shaft sensor? Normal symptoms include problems re-starting when warm and once cooled, car behaves as normal. Would recommend a diag to see what codes are generated. Had this problem on a previous E46 330ci

Edit - from memory the car would crank but not start but it was a manual so this may not be similar issue.

Edited by padhinbed on Monday 14th August 07:43