Cloud of Diesel when starting the car

[meckanix]

Hi All,
I'm new to this forum and I tried a search 1st and didn't find what I was looking for.

I recently bought a Seat Leon SX 110bhp 53 plate diesel and I have a slight concern when trying to start the car.

History
In December it went in for it's 70,000mile service and my mechanics noticed that a lot of the parts were still the originals i.e. filters, belts, plugs ... etc. So after a costly change out they were all replaced for new Bosch parts

Now obviously with the weather being colder I know that the glow plugs need a little longer before they're ready and as a rule of thumb I always start the electrics whilst I settle into the car so I know that after (upto a good 30 - 60 seconds) the car will definately be ready. Before the service I really struggled to get the car started, but I was hoping now it would be better

Issue
When trying to start the car you here the starter motor kick in and the enige tries to turn over as normal, but this can take a few morn seconds than normal and leave a rather large cloud of unburnt diesel in the air. At 1st I thought it was down the extremly cold weather of late, as the car does stand outside, but there have been occasions where it's not being too cold. I know Diesel has a higher temperature for combustion, but they are extremely reliable in the cold.

One thing I have noticed is that if I'm not paying enough attention when trying to start the car and I accidently turn the engine off whilst it's trying to splutter into life (i.e. I think I heared the engine kick in) and I try it again after a few seconds (quickly let the glow plugs have there time) it will start immediately.

Thoughts
Is it the way I start the car? or is it something mechanical i.e. the plugs or the relay?

 

[Markyboyt]

Hi All,
I'm new to this forum and I tried a search 1st and didn't find what I was looking for.

I recently bought a Seat Leon SX 110bhp 53 plate diesel and I have a slight concern when trying to start the car.

History
In December it went in for it's 70,000mile service and my mechanics noticed that a lot of the parts were still the originals i.e. filters, belts, plugs ... etc. So after a costly change out they were all replaced for new Bosch parts

Now obviously with the weather being colder I know that the glow plugs need a little longer before they're ready and as a rule of thumb I always start the electrics whilst I settle into the car so I know that after (upto a good 30 - 60 seconds) the car will definately be ready. Before the service I really struggled to get the car started, but I was hoping now it would be better

Issue
When trying to start the car you here the starter motor kick in and the enige tries to turn over as normal, but this can take a few morn seconds than normal and leave a rather large cloud of unburnt diesel in the air. At 1st I thought it was down the extremly cold weather of late, as the car does stand outside, but there have been occasions where it's not being too cold. I know Diesel has a higher temperature for combustion, but they are extremely reliable in the cold.

One thing I have noticed is that if I'm not paying enough attention when trying to start the car and I accidently turn the engine off whilst it's trying to splutter into life (i.e. I think I heared the engine kick in) and I try it again after a few seconds (quickly let the glow plugs have there time) it will start immediately.

Thoughts
Is it the way I start the car? or is it something mechanical i.e. the plugs or the relay?

So the fault isn't since the service then.
Initial thoughts of possible a leaky injector, or maybe a knackered pre supply pump or something

 

[meckanix]

Hi Markyboyt,
No it's definately much better since the service. I know the guys in the garage and the really did a good job as due to a lot of the part still being original (they should have been changed / sorted at earlier services) and causing the intial issue of the glow plugs not heating up to the correct temperature

I'll be honest and say I have consider the fuel supply system, as when I put my foot down the car really flys I was just curious to see anyone else seem to be having this issue in the cold, as when the temperatures are +5*c then maybe 1 in 20 starts might be as above, but certainly when it's +8 - 10 then it's fine everytime

 

[devonfr150]

As soon as you turn the ignition on the glow plugs will heat up the cylinders if you are waiting for 30-60 seconds the temperature may be dropping again? Try turning the ignition on let the glow plugs warm up and then try starting without waiting, see if that helps at all? Just a thought!

 

[S3 AKR]

The glow plugs prime as soon as you unlock the car don't they ?? As soon as they have done their bit they cut out as they only heat the combustion chamber so that when the fuel enters it, it heats up rapidly as it is compressed by the piston rising and burns and so the cycle begins.

I think that's right.

Also, if the glow plugs are heating then the light on the dash (the curly one!) lights up until they stop heating, at which point it goes out. You will rarely see it on due to the glow plugs priming when you unlock the car.

So my point...... start the engine as soon as you get in the car - don't wait 30-60 secs as you will lose the benefit of the preheat from the glow plugs..... and it might still smoke a fair bit on starting. Mine does and always has.

 

[volvic]

re the plugs, i dont think they "prime" when you unlock the car, as i always see my glow plug light when i stick the key in. soon as it goes out i start the car up...
I also get a cloud of smoke when starting it up, i'm pretty sure a lot of others also get this.

how old is the battery? my bet would be on a new one sorting it

 

[UncleFester]

I turn mine on and as soon as the glow plug light goes out, i start it.

 

[dholdi]

I turn mine on and as soon as the glow plug light goes out, i start it.

Yes, same here. The glow plug light goes out after 2-3 secs. My previous pug diesel took around 10 secs before going out. Whether they pre heat or are a lot higher rated and draw a lot more current I dont know.

 

[Toxic]

had this issue before on my old leon. the timing belt had been stretched when fitted (or an incorrect one used). i tried plotting a TDI Timing chart with VAG-COM. it reported the timing was too retarded to plot a graph.

once the car was warm you could not tell the difference. car started fine. but on cold mornings i had serious issues to start it.

Seat Dealer had done my timing belt a few months before. they ended up replacing the timing belt which fixed the issue. (free of charge might I add)

have you had a timing belt changed recently?

 

[Muttley]

From what I understand, the glow plugs come on when you turn the key in the ignition lock (not when you open the door, that's the fuel pump in some other cars).

The glowplugs kick in below 9°C. When you turn the electrics on (first turn of the key) all the lights go on as a system startup check. If it is below 9°, the glowplug light will stay on (while the others go out), indicating when the plugs are glowing. Once the light goes out the plugs have stopped heating, and you should start the car straight away. The maximum glow period is 20 seconds.

The ECU takes a reading of coolant temperature to decide the glow period (not the outside air temperature sensor, the coolant temperature. This gives the best indication of the state of the engine). So it's possible that you have a faulty coolant temperature sensor.

A small cloud of smoke (not diesel fuel, soot, partly-burned fuel) is not unusual, although having disabled the EGR I see relatively little at any time. There is always a faint smell of soot when I start up though.

 

[meckanix]

Hi All,
Thanks for all your replies. Just to clear up a few points / questioned asked.

• Timing Belt - Done in the December service with it being the 70k service
• Glow Plugs - Before the service I'd be lucky to see the indicator light come on at all. Now it responds as normal (i.e. the colder it is the long it stays on), but for never more that 5 seconds
• The cloud - obviously due to the weather it's more noticable, but I understand that a small amout is normal
• Starting the car - I never thought of turning the engine shortly after the light went out, I was always under the impression that they would keep heating until the engine had complete started, so I'll give that a go.

Additonal Notes
(Obviously) if I drive to work and then take the car out at lunch then there is no issue, but if it's left for more that about 6 - 8 + hrs then this is when the biggest clouds are formed

 

[UncleFester]

Hi All,
Thanks for all your replies. Just to clear up a few points / questioned asked.

• Timing Belt - Done in the December service with it being the 70k service
• Glow Plugs - Before the service I'd be lucky to see the indicator light come on at all. Now it responds as normal (i.e. the colder it is the long it stays on), but for never more that 5 seconds
• The cloud - obviously due to the weather it's more noticable, but I understand that a small amout is normal
• Starting the car - I never thought of turning the engine shortly after the light went out, I was always under the impression that they would keep heating until the engine had complete started, so I'll give that a go.

Additonal Notes
(Obviously) if I drive to work and then take the car out at lunch then there is no issue, but if it's left for more that about 6 - 8 + hrs then this is when the biggest clouds are formed

Definitely change the way you start it That's unburnt diesel because the glow plugs are cooling down by the time you start it

 

[meckanix]

Sweet I'll give that a go, as undoubtedly there will be some driving to do this weekend.

Thanks again to everyone I'll let you know what the results are on Monday

 

[meckanix]

I just ran a quick test today as I need to pop out. I turned the ignition as soon as the glow plug light cleared, but this made no difference. If anything it produced a larger cloud of smoke than before.

Obviously when I was due to do my return leg of the trip after about 45mins everything was fine and the car started immediately.

Vague Conclusion
So far I think it's due to the weather been sooo cold, as that is the only common denominator (due to the car standing outside all the time). But I can't work out how this is effecting the car ... the mind boggles. Either way more testing tomorrow.

 

[devonfr150]

But did the car start any quicker at all?

 

[meckanix]

No, unfortuately not. It took a good 5 seconds of the engine struggling to turn

 

[rallynut]

think its the weather

 

[Markyboyt]

Is the car ever left for long periods of time or is it driven every day?

 

[Muttley]

I think your glow plugs are shot. Either the plugs themselves (more than one, perhaps all four) or the relay. Can you work with a multimeter, to find out if they are getting voltage? Procedure is, remove connector to engine coolant temperature sensor (simulates a stone-cold engine), detach electrical connection to glowplug, attach test leads to measure voltage at the glowplug connection, switch on ignition. Glowplugs should get +12v for 20 seconds.

 

[Robb1990]

Id put my money on a coolant temp sender. Mines the same sometimes, but recently its been fine, firing 2nd spin of the starter/ engine. If it got worse the longer the engine was stood not running, that would points towards a leaky injector, but you would get other running problems more than likely. For the £13 it costs for a sender, id get it done personally.