Is it necessary to wait for Glow Plug light to go off before cranking a Diesel?

neel385 · 16th November 2010, 16:46

In hot engines, the glow plug will automatically switch off earlier than in cold engines. So that kind of sorts out the issue of waiting for a long time with a hot engine. And further, since we have decided to buy a diesel, it would make a lot of sense to follow all precautions laid out for this kind of an engine.
(Off topic) I have found that the engine start is smoothest when I crank about 5 secs after the glow indicator has gone off. Like jav in post #5 points out, supply to the heating elements continues even after the indicator goes off and that might explain it!

tsk1979 · 16th November 2010, 17:04

No problems for engine, but in some cars, glow plugs have hard coded 5 second timer.
So even if you crank the engine, the circuit does not cut off the glow plug before 5 seconds.
This means damage to the glow plug.
So its always better to wait.
I am not sure whether the glow plug timer in the indica/indigo has auto cutoff on crank.

RGK · 17th November 2010, 22:16

I think modern day diesels heater plugs are controlled by sensors based on the engine heater plug temperature and glows off automatically.
Newer engines have more compression and so the glow plug goes off very soon. But when the engine becomes older, the glow plug timer increases slowly.

I think during signals there is no need to wait for the glow plug to go off before cranking the engine.
As per tsk I am not sure of hard coded timer for glow plugs. But when starting for the first time, it is mandatory to wait for glow plugs to go off and then crank the engine.
In older diesel engines like Matador, glow plug is heated manually by the driver and there will be a indicator to show the plug is heated fully and the engine can be cranked.

Sheel · 17th November 2010, 22:57

Quote:

Originally Posted by anilisanil

And I thought that glower plug does not go on unless it is required. Like in my Figo TDCi, it never turned on so far!

Is there no glow plug lamp in a Figo TDCi?

If no, how to determine when to crank up?

NST440 · 18th November 2010, 00:17

What i feel is that glow plugs should be given due importance as they are for a purpose, esp. if the vehicle is a tata then glow plugs are more then necessary, i still see my friends indica struggling to start without at least 5 times giving glow plugs heat to the engine.

I do not find it a big deal to wait for the glow plugs to go on my toyota or ford, i guess they increase engines life & those few secs are worth it !!

IndigoXLGrandDi · 18th November 2010, 16:57

Quote:

Originally Posted by neel385

In hot engines, the glow plug will automatically switch off earlier than in cold engines. So that kind of sorts out the issue of waiting for a long time with a hot engine.

The car for which I had asked is Indigo LS (May 2004) which has run 2,07,000+ kms. The Engine is IDI (In Direct Injection).

The Glow Plug Indicator does not turn off before at least 10-15 secs. when the Engine is Hot (Half Mark and Radiator Fan On) and atleast 20-30 seconds when the Engine is Really Cold.
If the Engine is Hot, why does the Glow Plug take 10-15 secs. to turn off?

Quote:

Originally Posted by RGK

I think modern day diesels heater plugs are controlled by sensors based on the engine heater plug temperature and glows off automatically.

The Indigo XL Grand DiCOR (May 2007) which has run 1,20,000+kms. Its Glow Plug turn off within 2-3 secs. irrespective of Engine Temp.
Same goes for Xylo E8 with ABS (Nov.2009) which has 65,000+kms.
Both(Indigo DiCOR and Xylo) are Common Rail Diesel Engines.

Quote:

Originally Posted by NST440

i still see my friends indica struggling to start without at least 5 times giving glow plugs heat to the engine.

The Glow Plug has worn out. Tell your friend to replace the worn out plugs with New Ones.

I will wait for Glow Plugs to turn off before cranking the Engine to avoid strain on the battery as rightly mentioned by GTO.

Thanks all for helping me.

anilisanil · 18th November 2010, 17:20

Quote:

Originally Posted by Sheel

Is there no glow plug lamp in a Figo TDCi?

If no, how to determine when to crank up?

There is, but it has never been used by my car at least until now. Of all the Figo TDCi users I knew, there is only one who reported that his glow plug went on for a few seconds. Apparently, Figo's ECU has sensors that turn on the glow plugs depending upon the temperature of intake air.

Me being a noob, I invariably assumed that it would be like that in all the cars, which evidently is not the case!

tsk1979 · 18th November 2010, 17:38

The older indigo had the 5 second timer(as indica) and it should heat for 5 seconds, not more not less. there is something wrong with glow plug timer if it stays on for so long!
Its an expensive part though(1700)

IndigoXLGrandDi · 18th November 2010, 17:45

Quote:

Originally Posted by tsk1979

The older indigo had the 5 second timer(as indica) and it should heat for 5 seconds, not more not less. there is something wrong with glow plug timer if it stays on for so long!
Its an expensive part though(1700)

What should I check for the More Time Delay?
Yes its expensive.

kadanaJ · 18th November 2010, 20:12

Since Diesels have to idle for about 40 seconds after starting, and 60 seconds before turning the engine off, isn't it a bad idea to turn them off at signals in any case?

v.anand · 18th November 2010, 20:38

Is it only diesel cars which come with "wait till glow plug off" funda?

The lone petrol car I have seen that needs to wait before cranking is the Palio 1.6 where a fuel sprinkler kind of a symbol is glowing for like 3 to 5 seconds. What is the need and purpose for it, AFAIK petrols don't need it. So can anyone explain why it is how it is?

The head mechanic at Concorde A S S also said the same thing when I asked him to wait for the light to go off before cranking. I follow it religiously but its a pain to enforce it on other drivers or mechanics who drive the car occasionally.

neel385 · 18th November 2010, 21:39

Quote:

Originally Posted by IndigoXLGrandDi

The Glow Plug Indicator does not turn off before at least 10-15 secs. when the Engine is Hot (Half Mark and Radiator Fan On) and atleast 20-30 seconds when the Engine is Really Cold.
If the Engine is Hot, why does the Glow Plug take 10-15 secs. to turn off?

When have you last had the glow plugs checked? It may so happen that one or more glow plug is not functioning properly because of which this is happening.

rakesh_r · 18th November 2010, 21:51

I guess its better to crank the engine after the glow plug indicator gets off,as gto had pointed out as the battery is already at load-crank motor,fuel pump and glow plug and i guess the diesel engine requires max juice from the battery during start up.Though i have never seen my cars glow plug indicator glow for more than a second or so.

Digital Vampire · 18th November 2010, 22:04

In my IDI Indigo, the glow-plug timer is fixed to 5 seconds irrespective of the temperature of the engine. Whereas on my Tucson (CRDI), the glow-plug timer varies between 1 sec to 5 sec depending on the engine temperature.

aoussie · 21st November 2010, 17:56

i always leave the engine running.cant take a chance. what if she does not start? faced this problem once at turn which goes from sion to bandra and was right in front, and she refused to start.i wont forget that.the starter was at fault. had to get it reconditioned by the company on extended insurance. so its engine on for me always.

16th November 2010, 16:46	#16
neel385 BHPian Join Date: Nov 2007 Location: Kharagpur Posts: 530 Thanked: 430 Times View My Garage	In hot engines, the glow plug will automatically switch off earlier than in cold engines. So that kind of sorts out the issue of waiting for a long time with a hot engine. And further, since we have decided to buy a diesel, it would make a lot of sense to follow all precautions laid out for this kind of an engine. (Off topic) I have found that the engine start is smoothest when I crank about 5 secs after the glow indicator has gone off. Like jav in post #5 points out, supply to the heating elements continues even after the indicator goes off and that might explain it!
	() Thanks

16th November 2010, 17:04	#17
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,695 Thanked: 23,484 Times View My Garage	No problems for engine, but in some cars, glow plugs have hard coded 5 second timer. So even if you crank the engine, the circuit does not cut off the glow plug before 5 seconds. This means damage to the glow plug. So its always better to wait. I am not sure whether the glow plug timer in the indica/indigo has auto cutoff on crank.
	() Thanks

17th November 2010, 22:16	#18
RGK Senior - BHPian Join Date: Feb 2010 Location: DPM and CHN Posts: 1,935 Thanked: 1,367 Times	I think modern day diesels heater plugs are controlled by sensors based on the engine heater plug temperature and glows off automatically. Newer engines have more compression and so the glow plug goes off very soon. But when the engine becomes older, the glow plug timer increases slowly. I think during signals there is no need to wait for the glow plug to go off before cranking the engine. As per tsk I am not sure of hard coded timer for glow plugs. But when starting for the first time, it is mandatory to wait for glow plugs to go off and then crank the engine. In older diesel engines like Matador, glow plug is heated manually by the driver and there will be a indicator to show the plug is heated fully and the engine can be cranked.
	() Thanks

18th November 2010, 00:17	#20
NST440 BHPian Join Date: May 2010 Location: Jalandhar Posts: 286 Thanked: 543 Times	What i feel is that glow plugs should be given due importance as they are for a purpose, esp. if the vehicle is a tata then glow plugs are more then necessary, i still see my friends indica struggling to start without at least 5 times giving glow plugs heat to the engine. I do not find it a big deal to wait for the glow plugs to go on my toyota or ford, i guess they increase engines life & those few secs are worth it !!
	() Thanks

18th November 2010, 17:38	#23
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,695 Thanked: 23,484 Times View My Garage	The older indigo had the 5 second timer(as indica) and it should heat for 5 seconds, not more not less. there is something wrong with glow plug timer if it stays on for so long! Its an expensive part though(1700)
	() Thanks

18th November 2010, 20:12	#25
kadanaJ BHPian Join Date: Apr 2010 Location: Mumbai Posts: 632 Thanked: 1,205 Times	Since Diesels have to idle for about 40 seconds after starting, and 60 seconds before turning the engine off, isn't it a bad idea to turn them off at signals in any case?
	() Thanks

18th November 2010, 20:38	#26
v.anand BHPian Join Date: Sep 2009 Location: Bangalore Posts: 343 Thanked: 97 Times	Is it only diesel cars which come with "wait till glow plug off" funda? The lone petrol car I have seen that needs to wait before cranking is the Palio 1.6 where a fuel sprinkler kind of a symbol is glowing for like 3 to 5 seconds. What is the need and purpose for it, AFAIK petrols don't need it. So can anyone explain why it is how it is? The head mechanic at Concorde A S S also said the same thing when I asked him to wait for the light to go off before cranking. I follow it religiously but its a pain to enforce it on other drivers or mechanics who drive the car occasionally.
	() Thanks

18th November 2010, 21:51	#28
rakesh_r Senior - BHPian Join Date: Nov 2009 Location: Pune Posts: 2,088 Thanked: 3,432 Times	I guess its better to crank the engine after the glow plug indicator gets off,as gto had pointed out as the battery is already at load-crank motor,fuel pump and glow plug and i guess the diesel engine requires max juice from the battery during start up.Though i have never seen my cars glow plug indicator glow for more than a second or so.
	() Thanks

18th November 2010, 22:04	#29
Digital Vampire BHPian Join Date: Jul 2004 Location: Utopia! Posts: 605 Thanked: 121 Times	In my IDI Indigo, the glow-plug timer is fixed to 5 seconds irrespective of the temperature of the engine. Whereas on my Tucson (CRDI), the glow-plug timer varies between 1 sec to 5 sec depending on the engine temperature.
	() Thanks

21st November 2010, 17:56	#30
aoussie BHPian Join Date: Oct 2010 Location: new bombay Posts: 31 Thanked: 5 Times	i always leave the engine running.cant take a chance. what if she does not start? faced this problem once at turn which goes from sion to bandra and was right in front, and she refused to start.i wont forget that.the starter was at fault. had to get it reconditioned by the company on extended insurance. so its engine on for me always.
	() Thanks