Pre-heating w/ glow plugs

[SinNH]

I don't know about any other series, but on my L series the glow plugs are " automatic timing" on the on position of the key, which means they shut off when the CPU thinks the time is enough. Mine, stay on, regardless of outside temp for about four seconds. This morning it was 5* F when I started the machine, I cycled the glow plugs cycle three times and probably could have used a couple more. Is this the way the pre-heat system is supposed to work?
No block heater on the Bota, stock heater on the JD.
It just not seem correct, to me, that the "auto" pre heat cycle is four seconds when it it 55* and four seconds when it is 5* F.

On my other tractor when the temp is around zero, I pre heat for 25 seconds and could probably go more at times.

Thanks!

 

[retired farmer]

I don't know about any other series, but on my L series the glow plugs are " automatic timing" on the on position of the key, which means they shut off when the CPU thinks the time is enough. Mine, stay on, regardless of outside temp for about four seconds. This morning it was 5* F when I started the machine, I cycled the glow plugs cycle three times and probably could have used a couple more. Is this the way the pre-heat system is supposed to work?

On my other tractor when the temp is around zero, I pre heat for 25 seconds and could probably go more at times.

Thanks!

That is the same way my L3301 works, and the other tractor you have operates like my old Ford operated.

 

[je1279]

I don't know about any other series, but on my L series the glow plugs are " automatic timing" on the on position of the key, which means they shut off when the CPU thinks the time is enough. Mine, stay on, regardless of outside temp for about four seconds. This morning it was 5* F when I started the machine, I cycled the glow plugs cycle three times and probably could have used a couple more. Is this the way the pre-heat system is supposed to work?

On my other tractor when the temp is around zero, I pre heat for 25 seconds and could probably go more at times.

Thanks!

On my LX you need to manually hold the key in the on position for as long as you want the glow plugs to operate. The manual has times ranging from 0 seconds to 10 seconds depending on the temperature. If the L series has some type of smart function for the glow plugs, I would just wait for the light to go off and start it up.

 

[greg86z28]

I typically run the glow plugs for the prescribed time (5-10 seconds), then crank it over. I don't recall cranking time, but 5-10 seconds. My B2601 always starts right away. If for some reason it wouldn't start, I would repeat the process (glow plugs, then cranking).

I'm also a fan of block heaters. I know modern diesels start great in colder weather, but when I can, I use a block heater just to make the process easier. With that being said, if it wasn't plugged in because I forgot or whatever other reason, I wouldn't be afraid to start it anyways. But I do like having that block heater assistance when I can.

 

[Dave_eng]

I typically run the glow plugs for the prescribed time (5-10 seconds), then crank it over. I don't recall cranking time, but 5-10 seconds. My B2601 always starts right away. If for some reason it wouldn't start, I would repeat the process (glow plugs, then cranking).

I'm also a fan of block heaters. I know modern diesels start great in colder weather, but when I can, I use a block heater just to make the process easier. With that being said, if it wasn't plugged in because I forgot or whatever other reason, I wouldn't be afraid to start it anyways. But I do like having that block heater assistance when I can.

Depending upon the model and year of your Kubota the following info can be a big help especially if you use a block heater.

In very cold weather, with the block heater plugged in, the glow plug sensor (which is looking at coolant/block temperature) will lock out the glow plugs or greatly reduce their on time as it senses a warm engine.

However, starting, in these circumstances can be rough and worrisome as the engine is still inhaling very cold air.

The trick is to put the shuttle shift lever in forward and turn the key to the start position.

You will hear a relay click on. I count to 10, put the shuttle back into the neutral position and start the engine.

Makes an amazing difference.

On newer models, M7060 perhaps, Kubota realized the problem and provided software which would allow the dealer to set which sensor decided the GP on time. When owners of the M series tractors install their own block heater, they won’t get the software change and need to use the manual way to control the GP’s. The software change has the GP's sensing air temp.

I know there are GP work around on other Kubota models but I was only interested in M7040’s at the time.

I learned of this undocumented feature from a Kubota mechanic who was moving around many machines for snow clearing. It was very cold and the fact that he had no trouble getting them to fire caught my eye.

Dave

 

[PoTreeBoy]

I don't know about any other series, but on my L series the glow plugs are " automatic timing" on the on position of the key, which means they shut off when the CPU thinks the time is enough. Mine, stay on, regardless of outside temp for about four seconds. This morning it was 5* F when I started the machine, I cycled the glow plugs cycle three times and probably could have used a couple more. Is this the way the pre-heat system is supposed to work?

On my other tractor when the temp is around zero, I pre heat for 25 seconds and could probably go more at times.

Thanks!

According to the WSM, your CPU reads the coolant temperature and adjusts the preheat time accordingly. If you have a block heater, it could be fooling your CPU.
Edit: Dave explained it better.

 

[chim]

The L4240 has a self-timer that starts when the key is twisted. When the light goes out the tractor sounds like the engine cranks two revs and it starts.

The Ford 1210 has glowplugs that are manually controlled and an indicator on the dash that looks like a little resistive cigarette lighter element. As the key is held, the element begins to glow. As it gets hotter the color goes from red to orangeish. Usually starts after a few revs but not as fast as the Kubota.