Glow plug light staying on

[Mercedesstar]

Hi all
The glow plug light is staying on on my 99/2000 320Cdi for a while after I have started the car. I have owned the car for about 4 weeks and after having read through the paperwork that came with the car ( it has got full MB service history ) it was noted in a service report from 2009 ( the manifold was changed amongst other things, the bill came to £1800), that the `glowplug light on - unable to remove as may snap in cylinderhead`. Has anybody experienced something similar and anybody got any advice? In this weather it is not a problem as such, but come winter it may be a different thing.

 

[walsi]

Hi ya, your info is correct and they can snap in the head but there are kits available for there removal if they do. Been a CDI engine you should not need the glow plugs in this country unless we have a real severe winter and even then if you have a good battery it should still go ok.

Martin

 

[Mercedesstar]

Thanks for that, Martin. I was surprised that a Mercedes Benz garage had given up on it.
Will make sure the battery is up to the job.

Cheers
Martin

 

[Buffers]

I believe there is a mobile company that specialise in removing broken glow plugs (think l read it somewhere) l would get it sorted if l were you. Starting will be a problem in very cold weather. It is also possible that it is the supply lead to the glow plug that has failed.

 

[walsi]

Just to make myself clear starting should not be a problem in the uk on a cdi engine unless the temp gets very very cold and i am talking the sort of cold that you only get at the top of scotland in a bad winter and even then if you have a good battery it would probably start.

Martin

 

[panason1c]

Just to make myself clear starting should not be a problem in the uk on a cdi engine unless the temp gets very very cold and i am talking the sort of cold that you only get at the top of scotland in a bad winter and even then if you have a good battery it would probably start.

Martin

+1

As above, g/plugs not needed for starting on a cdi engine, they are mainly fitted to help reduce emissions (initial puff of black smoke) on start-up.

Probably the reason why MB only advised about the plug being likely to snap rather than push for it to be replaced.

 

[Aerialmark]

Just to make myself clear starting should not be a problem in the uk on a cdi engine unless the temp gets very very cold and i am talking the sort of cold that you only get at the top of scotland in a bad winter and even then if you have a good battery it would probably start.

Martin

Just to throw my two-penneth in I have had the same problem and the chaps at the garage said just the same that it could be a problem getting them out and besides on a CDi engine you do not need them.These lads at Read Garage near Burnley are Mercedes trained so know there stuff and have not let me down so far............

 

[G.P]

Hi ya, your info is correct and they can snap in the head but there are kits available for there removal if they do. Been a CDI engine you should not need the glow plugs in this country unless we have a real severe winter and even then if you have a good battery it should still go ok.

I have a 1998 312D Sprinter, which I'm the first owner of. It has a 5 pot engine, in the hand book to this when the glow plug light comes whilst driving it states there is water in the diesel fuel filter, sometime last year one glowplug stoped working (one nearest the bulk) which I've not changed, in the winter I notice the difference in starting. .

 

[walsi]

I have a 1998 312D Sprinter, which I'm the first owner of. It has a 5 pot engine, in the hand book to this when the glow plug light comes whilst driving it states there is water in the diesel fuel filter, sometime last year one glowplug stopped working (one nearest the bulk) which I've not changed, in the winter I notice the difference in starting. .

Hi ya, that is because you don't have a cdi engine, you need all the glow plugs working on the D series vito's and sprinters for them to start in cold weather, the 5 cylinder will start with 4 cylinders working as long as you have a good engine but you would be lucky to get a 4 to start with 3 plugs working. I used to have a 6 cyl td volvo with the old transporter engine and that would not start if all 6 plugs weren't working

Martin

 

[Buffers]

Are you saying that you don't need glow plugs at all to start a cdi engine? Just asking, interested.

 

[walsi]

Yeah they should not be required at all on a CDI engine unless the temperature is in the sort of area of -6 and below and even then if you have a good battery and a sound engine it will start after a few turns. If you actually timed how long your glow plug light stayed lit you would realise that is nowhere near enough time to heat up the cylinder. If you put a test light on a glow plug you will find that power to it carries on for probably another 20secs or more. Just have a listen to the glow relay go click if you don't believe me and see how much longer they work after your engine is running. Most people think turn the key wait 5 secs and away we go, well that was not enough time for the glow plug to even get hot. If you have problems starting a CDI engine in normal temps without the use of glow plugs you have either not enough cranking speed (duff battery) a fuel related problem or not enough compression

 

[Mercedesstar]

Interesting. I will leave it for now, sorting a few cosmetic bits out at the moment, and as you guys say, there`s no rush to get them sorted. Thanks for all your input.

 

[johnsco]

If you actually timed how long your glow plug light stayed lit you would realise that is nowhere near enough time to heat up the cylinder.

The time that the glow plug stays lit is to heat the glow plug ... That is to make it glow in order to initiate ignition of the mixture under compression.
It is NOT to heat up the cylinder.

 

[walsi]

I disagree, take a glow plug out and put power to it, the time most glow plug lights stay lit is not even long enough for them to make the glow plug too hot to touch let alone heat up the fuel mixture. The idea with a using a glow plug is to heat the cylinder, air and fuel, if you just want to heat the fuel to help ignition use a line heater like a lot of lorries and cars do in cold climates. They heat the air up that is going into the cylinder to aid ignition aswell as the fuel. Just go and put a test light on your glow plugs and see how long they run before the relay switches off and then see how long before the light goes out. The light goes out way before the relay switches off. So the question is why do the lights go out so quick ?

Martin

 

[johnsco]

The light times out to tell you when to fire up the engine.
The glow plug operation times out some time after this ... Often between 10 and 20 seconds depending on the car.
It is the engine running for this 20 seconds that warms up the cylinder ... Not the tiny little glow of the glow plug.
The thermal capacity in the glow plug tip is minute compared with the thermal capacity of the cylinder, cylinder-head and piston crown.
Sure - Heat the fuel in the line.
Sure - Cool your air using the intercooler.
The glow-plug initiates the ignition when the engine is cold.

Some diesel engines will start without the glow plugs ... Although they might grunt and fart a bit for the first few seconds.
Certain other diesel engines certainly will not start from cold without the glow plugs.
It depends on the design of engine.
Diesels come in many different shapes sizes and applications --- From small very-efficient diesels in modern road cars to enormous marine diesels as big as a house.

 

[walsi]

Diesels come in many different shapes sizes and applications --- From small very-efficient diesels in modern road cars to enormous marine diesels as big as a house.[/QUOTE]

And we are talking about a CDI engine which doesn't need the use of glow plugs, the reason they are fitted is explained earlier in this thread.
On the same subject years ago Vauxhall had a very well known issue with problem starting on there diesel engines and this was down to the glow light timer in the relay slowly reducing the time the glow light was staying on, the result was a lot of people could not start there cars. Merc had similar things happen with the relay on the vito as did lots of manufacturers. The advice was when the engine was cold to operate the glow plugs and count to 20 then turn the key, bang engine starts first turn every time. So how would that work if you were not using the glow plug to heat the air in the barrel and the barrel itself, there is no fuel in there till you operate the starter, the glow plug would have been at full heat after probably 10 secs , but it still wouldn't fire, leave it 20 secs and bang everything is nice and toasty and your engine fires straight away

Martin

 

[panason1c]

The g'plugs on a cdi engine are fitted only to aid a 'clean burn' and thus reduce smoke during the first moments of starting the engine, they are fitted for emission reasons. A healthy cdi engine will always start without the aid of g'plugs.. (just unplug the relay and try it)

 

[walsi]

Exactly what was said earlier, its a totally different principal to the original use of glow plugs but they will still aid starting in cold conditions but are primaly fitted to aid emissions.

Martin

 

[johnsco]

There are a number of engines with traditional injector pumps that will start without the use of glow plugs if you crank them long enough.
It is the glow of the glow plugs that helps the air/fuel mixture to ignite in a cold engine.
It is the next 15 seconds of compression ignition that then goes on to warm the cylinders.
The minute heating element of a glow plug is not going to heat up the cylinders before you crank the engine.

 

[walsi]

It heats the air in the cylinder not the cylinder its self as such