Glow Plug Use

[john lalleman]

Maybe this is an old topic, but I have searched, and while there is some glow plug discussion, I found nothing either serious or in depth.

When using glow plugs to preheat for cold starts, does anyone have any better information or knowledge about what is the proper/correct amount of time to preheat before trying to start a diesel engine?

The reason I ask is this. After having had my B7300 for over 23 years, I had my first cold start issue this past week. In the past, it seems, I really have not had the need to start my engine in really cold weather. However recently, we had a couple small snow storms, nothing enough to warrant clearing the yard and drive, but freezing rain was in the forecast, and following that a much colder freeze. I decided to clear up what was down and around before the rain and freezing rain made a mess, and the forecast deeper freeze turning everything into a rutted skating rink.

As it was about 15F at that time, I put everything in neutral, depressed the clutch, moved the key to preheat, and held it there for 10 seconds, basically what the manual said, and has worked in the past, but I cannot attest to what the temps were when I did those cold starts. However, this time, the engine did not fire on the first try. So, I waited about 1 minute, and repeated the process, and once again, it did not start. So, I repeated it for a third time, and the engine started. I did my clean up and put the tractor away, but I got to thinking about this, as winter here is basically just getting started. I reread my user manual, and confirmed what I had done was what was prescribed.

The next day it was much colder, 7F, and I decided to do a test. I went out and began the cold start procedure, but this time I held the key in the preheat position for 20 seconds, and it started right up. I am now wondering if the user manual is being a bit cautious with the preheat time? Or if maybe there is a more widely used or accepted thought/theory/procedure ?

BTW, Happy New Year 2026 to all!

View attachment 4673726

on a kubota turn the ign switch on till the glow plugs click off.....then turn the switch off and turn on again 2 more times... then switch off again then crank the engine over and then it will smart on 1/2 of a revolution---works every time

 

[lectro88]

I don’t have a kabota, but here’s my input.
The first thing I have noticed with cold starts.
When the battery weakens in the slightest during startup, it’s usually over. Cold is hard on batteries too as we already know.
Also the other thing is the older some engines get the more cold natured they can get.

My 06 JD4720 has an intake grid heater. Can’t say I know it works but this unit starts every time even in single digits.

My 05 Takeuchi excavator has a 3 cyl. yanmar and it is the one that the battery has to be right to start in cold conditions.
Only gives me trouble when it gets close to battery replacement time.

Cheers

 

[kneedeep]

Check battery fluid level.
I checked the golfcart yesterday and spent rest of the day filling batteries with distilled water and charging them. Got 5 more to check and charge today!
They start and heat better with a hot battery .

 

[neilpaku]

I have a garden tractor, JD 430 with a 3TNA72UJ and that will not start without glowplugs in winter unless the block has been pre-heated for at least 6 hours. My Cat D2 takes a good couple of minutes of glowplug in sub-30 temps. My '26 F350 6.7 will start immediately even if I don't wait for the glowplugs. It's so fast that I don't hold the key to the start position - I just flick it to start and back to run and it starts every time. Only other engine I've encountered like that is an E9 Mack

 

[walnutman]

Do what it takes is the theme here. You won't hurt anything if you try too soon.

I don't know if my 2022 Yanmar YT359C even has glow plugs.
I'm in East Texas so it would be a rare occasion to even think about it.
But these new High Pressure Common Rail engines have the distinct advantage of being able to start easily in cold temps due to the atomization of the injector spray. Also increases power, efficiency and noise levels.

My 2004 Dodge Cummins is HPCR.
It does not have glow plugs. It uses a ribbon heating element in the intake stream to warm the incoming air.

Used to live in PA where we did get single digits and zero's in the winter. Tested it in the really cold and it would start in single digits without waiting but it did crank longer.

 

[chorsken]

I have a 25 year old JD 990, awesome tractor. Make sure everything is in neutral, then I turn the key to the glow plug position and count slowly to 20, then start it full throttle, as per the manual, quickly back off the throttle when it starts, been doing it every winter in NH, minus temps, does not matter always starts.

 

[MHarryE]

I moved to France in 1997. In France, at that time, 80% of the cars were diesel (better fuel economy, lower price for diesel). In the big box stores where we woud find stacks of spark plugs in the old days when we in America would get 10,000 miles or less from a set of plugs, they had glow plugs. When using every day, glow plugs were a weekend service item. What I'm getting at is its not out of the ordinary to need replacing glow plugs on diesels as they age. I have 2 older diesels needing the operator to control glow plug timing. My newer ones are controlled by the engine computer and are programmed for a certain time depending on engine temp when you turn the switch on. But when we have temperatures well below zero, I will cycle them a couple times before trying to start even when having the block heater plugged in as the block heater doesn't do much for heating incoming air although it helps cranking speed. Common rail systems usually wont inject fuel until crankng speed is above a certain level to prevent unburned fuel from washing down the cylinder walls.

 

[tassmannn]

I had to figure out last winter how to use the Glow plugs in my Kubota RTVX 1100C. While all my other diesels are all automatic, that one is a little tricky. You have the start turning the key to the start position, but not go all the way there, like half way before starter kicks in. Then it only takes a few seconds to get warm enough, and that was at 22 degrees.

 

[tassmannn]

I have a 25 year old JD 990, awesome tractor. Make sure everything is in neutral, then I turn the key to the glow plug position and count slowly to 20, then start it full throttle, as per the manual, quickly back off the throttle when it starts, been doing it every winter in NH, minus temps, does not matter always starts.

WOW that's a blast from the past. I use to own one years ago, and you are right, that's a nice machine. Wish I would have kept it, but have plenty to maintain as it is

 

[Bigmuddyriver]

I’ve found that it helps to start by having the throttle about a third of the way up from the idle position after the glow plug extinguishes.