2008 - BMW 730d - cold starting

[IceBoy]

Morning All,

My dad popped in this morning before his round of golf, complaining that his car turns over many times before starting.

Apparently it only happens in the winter period, when it is frosty.

The battery seems fine and it will crank ok but will need the engine to turn 8-9 times before starting. Normally it turns twice and fires.

730d 2008, full history with 101k on clock.

Thanks in advance.
IceBoy

[Toaster Pilot]

I'd guess some kind of temperature sensor that is telling the circuit controlling the glow plugs it's warmer than it really is.

[HustleRussell]

Does sound like there might be a minor pre-heat related issue, perhaps one or more of the glow plugs has failed.

[Dr Interceptor]

Does he let the glow plug light go out before cranking?

The number of people I see that jump straight into a diesel and turn it over like a petrol surprises me.

[Toaster Pilot]

Dr Interceptor said:

Does he let the glow plug light go out before cranking?

The number of people I see that jump straight into a diesel and turn it over like a petrol surprises me.

Even had tyre fitters do this in my old diesel which absolutely will not start unless you wait for the light to go out even if it's just been driven (it's a bit fked)

[IceBoy]

To be honest, I'm not sure about the light.

It has a starter button/key thingy. Maybe he is cranking to early.

I will check with him.

IceBoy

[surveyor]

Could also be an injector on the way out,

[philmots]

If it's anything like my old 335d.. When you put the 'key' in the slot and press the ignition button it doesn't actually start to warm the glow plugs, it only happens when you actually go to start.

In the cold mine would struggle, and the glow plug warming light would flash up briefly.

New glow plugs sorted the problem. At 100k if it hasn't had any I'd wager that's what it needs. Just good luck getting them out the head!

Think I got the actual BMW plugs online for £9 each.

[evo97]

Had a Glowplug relay/control module fail on my 330d located under the inlet manifold

[Dr Interceptor]

IceBoy said:

To be honest, I'm not sure about the light.

It has a starter button/key thingy. Maybe he is cranking to early.

I will check with him.

IceBoy

When you put the key in, and all the dash lights come on, there will be the glow plug light... it's a coil shape.

The older they get, the longer this stays on for. Let that go out, then push the starter button.

I have a 58 plate Astra Van, only on 50k miles, but if you try and crank it before the plugs are up to temp, it will turn over forever before starting.

You also get a big plume of smoke if you do it too early.

[Dr Interceptor]

philmots said:

If it's anything like my old 335d.. When you put the 'key' in the slot and press the ignition button it doesn't actually start to warm the glow plugs, it only happens when you actually go to start.

In the cold mine would struggle, and the glow plug warming light would flash up briefly.

New glow plugs sorted the problem. At 100k if it hasn't had any I'd wager that's what it needs. Just good luck getting them out the head!

Think I got the actual BMW plugs online for £9 each.

Really? That's a bit st if they don't start warming straight away...

[sinbad666]

As already mentioned - Glowplug control module, Glowplug or injector are the likely culprits. Ive got a 530d and the controllers are common.

[IceBoy]

Update....I borrowed the car for a couple of days and definitely cold starting problems.

No light on the dash when you insert the key when you press the start button it all lights up like a Christmas tree and immediately cranks.

I cant see no glow plug light????

I suspect the glow plugs might be on the way out but is there no light on the dash???

Furthermore, if you start the car for 15 seconds, turn off, it immediately starts fine.

IceBoy

[Vulgar LS2]

You don't get a light normally, I've had the glow plug light come on once last year when it was really cold, it lights up the center window where the time is normally, when it comes on you cant start the car until it's gone out.

[Motorrad]

IceBoy said:

Update....I borrowed the car for a couple of days and definitely cold starting problems.

No light on the dash when you insert the key when you press the start button it all lights up like a Christmas tree and immediately cranks.

I cant see no glow plug light????

I suspect the glow plugs might be on the way out but is there no light on the dash???

Furthermore, if you start the car for 15 seconds, turn off, it immediately starts fine.

IceBoy

Sounds like you are pre-heating the remaining functional glow plugs. Therefore, pre-heat the remaining functional glow plugs before starting the vehicle to avoid a big bill. Job, jobbed.

edit to add: my 6 cylinder BMW diesel is starting on 4 out of 6 glow plugs according to my diagnostics. It makes no difference so far in starting down to -1 degrees.

[S70JPS]

If my glow plugs come on there is just a delay in starting. One press of the starter sorts it. Before I knew this I wold press it again thinking it needed it and then the churning would start. Suggest trying just one push when it's cold.

[Urban Sports]

What are these glow plug lights people speak of?

Mine fires up in one crank even when it was -3 the other day.

[lbc]

IceBoy said:

I cant see no glow plug light????

I don't see a glow plug light on mine unless it is colder than about -8°C outside.

Most modern diesels are probably the same, as I have never had to wait for glow plug lights since the 1990's,
or during very cold winter mornings such as we had in 2010, when it was often -10°C.

Edited by lbc on Tuesday 26th November 20:37

[S70JPS]

I must confess I have only seen the light a couple of times in 150000 miles. If yo blink you miss it . I just know that if it is cold and it doesn't start instantly it will in a couple of seconds. Had it once last week at minus 3.

[Dr Interceptor]

Well, my 2011 Fiesta TDCi has a glow plug light, as does the 2012 Combo van, 2008 Astra Van, and 2013 E-Class.