Glow Plugs - How Long Do You Keep Them "ON" Before Cranking The Engine ?

[TheKubotaKing]

Hi everyone !

I've been watching a lot of YouTube Kubota videos lately, and notice how some guys will turn the key to ignite the glow plugs for 1 second or shorter sometimes. In a few Kubota tractor instruction videos, I've seen the instructor / salesman say that those plugs could be / should be ignited from 5 to 10 seconds, 10 seconds being the MAXIMUM in COLD weather. With that being said, should you be igniting the glow plugs for even 5 seconds, if it's summertime, and warm outside, and or if the engine has already been running 10 minutes or 30 mins earlier. I guess what I am also wondering is what really is the minimum amount of time you suggest igniting those glow plugs before cranking the engine ?

P.S. ( I have never seen anyone in any video btw, igniting those glow plugs for anywhere near 10 seconds. When you count that out loud, that's really a long time, and you are for sure shortening the life of those plugs. )

 

[Orangeglow]

I,ve got a BX2370, same engine as yours, and the first time each day, I count to 10 before hitting the start button. After it has initially warmed up to 2 bars on the temp gauge the first time, I find I can start it right away without any glow time for the rest of the day, during non winter use. In winter, it cools off quik, so if I need to start it again in a couple of hours after it has sat, I re glow the plugs again, to make starting it again easier on the engine.

 

[Nicfin36]

I have yet to use glow plugs. However, I am in Alabama and have not used the tractor in cold weather. My older tractor doesn't even have glow plugs.

I would say if the temperature if comfortable to you, there is no need to use the glow plugs. That's just my 2 cents as I am certainly no expert, just making assumptions from my experience so far. This what the manual says for my tractor:

Temperature Preheating Time
Over 0C (32F ) 2 to 3 sec.
0 to -5C (32 to 23F ) 5 sec.
-5 to -15C (23 to 5F ) 10 sec.

 

[85Hokie]

I'M with Orangeglow- on my BX2370 - I ALWAYS glow the plugs..... 3 or4 seconds in the summer and maybe 10-15 seconds in the winter - once "warm" engine - no glow.

On my B7100's - a glow is a must, in summer - I wait 3 clicks of the hour meter.... which is like 12 seconds. In the winter, I glow maybe 25 seconds. On those older B's it is a must - on the BX it make it easier to start.

 

[hagrid]

I believe the plugs expand and break electrical contact once they reach their upper temp limit. When they cool they reestablish continuity.

 

[GreensvilleJay]

I always preheat until the fuel guage registers steady on my BX23s, have 2yrs/400 hrs on her, always starts, Winter, Spring, Summer and Fall. easier than counting 'steamboats'.

 

[Stephen Wright]

On an L series I use, the glow plug lamp shuts off after a few seconds and then the engine fires right up. Not sure if the BX has an automatic sensor that does so.

 

[Henro]

What I have found is the colder it is the longer I keep the glow plugs on before trying to start. If the engine doesn’t start in the first half second, I release the key and apply the glow plugs again for a few seconds, then the engine starts right up.

i think warming the cylinders while there is some unburnt fuel in them makes a huge difference. This is for both my tractors.

 

[Nicfin36]

I'm a novice of sorts, but I cannot understand the reason to use the glow plugs when the weather is warm and the engine cranks immediately, which mine does. If the engine is old, hard to crank or it is cold weather out and the glow plugs help, that makes sense to me. Do glow plugs help the engine in any other way other than to crank the engine, like reducing carbon build up?

 

[85Hokie]

I'm a novice of sorts, but I cannot understand the reason to use the glow plugs when the weather is warm and the engine cranks immediately, which mine does. If the engine is old, hard to crank or it is cold weather out and the glow plugs help, that makes sense to me. Do glow plugs help the engine in any other way other than to crank the engine, like reducing carbon build up?

So, if you understand how a diesel engine works - it compresses the air to an incredible temperature and then it injects the fuel mist, If that cylinder is cold, it will "suck" the heat out of that compressed air and fuel a bit. The heating of the air is almost critical to get the air to explode when compression ends.

The glow plugs really have nothing to do with the cranking of the engine, unlike a compression release valve that does help tremendously - the glow plugs just heat the air in the cylinder for the first spin of the engine - this now will help the starter, since a warm cylinder will not need a lot of cranking to get it running. Warming the air/cylinder is a huge step forward on a new or old engine to help it get the process up and running.

I look at it this way - you have to get up and go outside and face the ugly cold, would you rather have a cup of coffee and get the innards warm? OR face the outside right off the bat. Ok - that is a crazy example but it does present a point.

 

[Nicfin36]

Ah OK. Yes, I understand a diesel combusts fuel using compression and it makes sense that warm diesel would be better to combust than cold diesel. My engines starts so fast, I just flick the key and almost immediately let go. All my cranking has been done so far when warm, probably not much colder than 70F.

 

[BruceP]

My 1980's vintage G5200 (D600 engine) uses a glowplug 'indicator' which is actiually a coil of tungston which glows as it heats up (like coils on electric stove).

As this 'indicator' gets hot, its resistance GOES UP.... thus reducing the voltage to the glowplugs. This is a self-regulating circuit to protect the glowplugs.

To specifically answer your question - I will glow for 20 seconds in the summer and over 60 seconds in the winter (sometimes a second glow is necessary) If the engine cranks for more than 10 seconds... more glowing is indicated.

Of course, A hot engine does not need to be glowed.

 

[wgator]

I dunno, call me old fashioned or whatever, but i would go by whatever times the operator's manual for the tractor said to do.

 

[GeoHorn]

Down here is relatively-warm Texas... I usually am starting my diesels (I have 3) in warmer climes that my “Yankee” friends. If it’s above 60-degrees (F) then I do not find it makes any difference if I use GP heat or not. If it’s below 60F, my M4700* still starts on the first compression-stroke as does my John Deere 4239 engine in my compactor.... but my little 3-cyl Kuvota RTV-X900 will spin and spin...but no joy.... until I give i t 5-seconds of GP heat...then it starts immediately. It’s the character of the individual engine designs, I think.

Do what your Owner’s Manual suggests.

*While the M4700 has a dedicated GP heat position on the key switch for pre-heating the GPs... the M4700 uniquely also automatically heats the GPs during ordinary starts while the starter is activated, unlike the other two engines, so this may not be apples-to-apples. However, the JD never gets GP heat until the temp drops below 40-50... nor does it need the GP heat until it gets that cool. So,... unless it’s a COLD morning, ... I just hit “start” and unless they don’t give me a running engine immediately... I don’t use GP heat. If it IS a cold morning...on ANY of them.... I give them the advantage of pre-heated GPs just to reduce the cranking effort and get ‘em running. (ALL of them get a few minutes of warm-up at idle speed before asking them to do anything.)

 

[SidecarFlip]

......Glo little Gloworm glimmer, glimmer.......... Me, I do the one thousand one, one thousand two, one thousand three thing and so on depending on ambient.

No glo above 60 at all.

Guess you could glo until the battery was dead and go back inside and have another hot cup of Joe.

Life is good most times.

 

[Lil Foot]

On my B7100's - a glow is a must, in summer - I wait 3 clicks of the hour meter.... which is like 12 seconds. In the winter, I glow maybe 25 seconds. On those older B's it is a must - on the BX it make it easier to start.

I agree. With my B7100, if the engine is hot, no glow necessary. If it's a little cool or the engine has been shut down a while, (like over lunch) I glow at least 5 or 6 clicks. If it is a really cold, first start up, I glow 15 to 17 clicks.
I also use the decomp knob momentarily to let it spin up when it's cold. The old boy usually starts on the first crank, regardless of temp.

 

[TheKubotaKing]

Wow, so glad I asked this question, it's like a snowball, I started it off, and now so many replies. I had NO idea that you could start a warm engine without even using the glow plugs. If a warm day in the summer, really no need either. The things you learn on this forum. I'm so thankful I joined. Love the conversation ! It's here you get REAL-LIFE experiences... and that to me is what counts. Thanks to those who have chimed in, awesome stuff !!

 

[85Hokie]

Wow, so glad I asked this question, it's like a snowball, I started it off, and now so many replies. I had NO idea that you could start a warm engine without even using the glow plugs. If a warm day in the summer, really no need either. The things you learn on this forum. I'm so thankful I joined. Love the conversation ! It's here you get REAL-LIFE experiences... and that to me is what counts. Thanks to those who have chimed in, awesome stuff !!

You will find a ton of info here - a lot of very talented people who have been there and done that - whatever that may be!

You will also find that a newer tractor may not need the glow as much as an older one. Some things get better with time, some need a little warming up before it works well!

 

[SidecarFlip]

You will also find that a newer tractor may not need the glow as much as an older one. Some things get better with time, some need a little warming up before it works well!

That not only applies to tractors, it applies to me. The older I get, the more 'warm up time' I require......

 

[Lil Foot]

That not only applies to tractors, it applies to me. The older I get, the more 'warm up time' I require......

I hear that!