L4240 White Smoke and Stumbling Idle on Cold Start

[Member]

Hi,

Recently my L4240 started producing about a half minute of white smoke with a stumbling idle on a cold start. See below for a video.

This has happened consistently on the last four or five starts. I turn the key and the glow plug relay makes a nice snap. I wait until the glow plug light goes out before cranking it over. It always starts on the first try. The outside temperature has ranged from 8 to 32 degrees Fahrenheit. The tractor is about a year old and has 50 hours on it. It is always parked inside an unheated building. I have owned it since new. I fill it with diesel from yellow 5 gallon cans. The fuel I'm using has been in there for several months. I don't use any diesel additive.

This is new behavior and something it has never done until the last four or five starts. Any ideas?

Thanks,

--
Dan

 

[Little Red Tractor]

Best first guess is bad/contaminated/moisture fuel. First thing would be to try some fuel conditioner. Might be a worth it to change your fuel filter. Always try the simple things first.

 

[avc8130]

My L45 sounds and acts like that when it is cold also. I did some searching on the web because my L39 never sounded like that. It seems to be that the 4cyl Kubota's are just like that in the cold from what I have found. Rumor was that Kubota adjusted injector timing for max power while still meeting the emissions and it is a bit too aggressive for cold smooth starts.

ac

 

[TripleR]

Looks just like my L5740 when cold. It makes more noise and puts out more smoke than my old L5030.

 

[lew61]

I have a new (less than 20 hours) L4240 and it's been starting fine in our winter temps (8-32 degrees). From past experience, I'd suggest taking Little Red Tractor's advice. White exhaust means water to me.

 

[kuboman]

If this just started then I would suspect the glow plugs are not up to snuff. Although my 5740 does that at 50*. If it is new for your machine then something has changed. Either the GP"s or fuel.

 

[crashz]

I suspect the fuel. Try a conditioner and check the water / fuel separator.

 

[nybirdman]

Yes,summer fuel and no additives.Add Powerservice or Howes.I use Powerservice year-round in my fuel for my L4240,always starts fine.I do have a block heater I use when real cold.

 

[art]

Try some power service it is what we use!

 

[Chilly807]

Try some fresh fuel as soon as you get the chance. If the fuel is several months old it will be summer fuel without the winter additive package. Adding an additive directly to the tank probably isn't a good idea as it's hard to mix it properly in the tank. It acts like it's missing on a cylinder or two until the heat builds up in the cylinders.
It may just be the nature of the beast, although you did say this is new behaviour. If it's just old/summer fuel it won't hurt much, other than running rough until it warms up a little. It works ok once the engine warms up? If you're getting some snow, it shouldn't take long to get rid of the tankful of fuel in it now.

Sean

 

[Ken45101]

My M5040 acts like that. The other equipment doesn't. (Well the 12 year old Kubotas put out black smoke for a bit.) This has been going on ever since I got the 5040. I suspect it's the design/timing and nothing to worry about.

 

[PhilY]

White smoke means water.
Black smoke means too much fuel.
Smoke with a Blue tinge is engine oil.

 

[PhilY]

My M5040 acts like that. The other equipment doesn't. (Well the 12 year old Kubotas put out black smoke for a bit.) This has been going on ever since I got the 5040. I suspect it's the design/timing and nothing to worry about.

The engine cranks a couple of times before it fires up. While this is going on, fuel is being delivered, and therefore has too much fuel once it comes to life. This and the fact that the cylinders aren't warmed up and able to consume all the fuel would be why I would think there's black smoke on start up.

 

[avc8130]

White smoke means water.
Black smoke means too much fuel.
Smoke with a Blue tinge is engine oil.

That is true in gas engines.

White some in a diesel at startup is indicative of cold cylinders generally.

ac

 

[PhilY]

That is true in gas engines.

White some in a diesel at startup is indicative of cold cylinders generally.

ac

Learned something new...thanks! I looked it up and it appears to happen when diesel comes through the exhaust intact and unburned. The exhaust will also have a slight diesel smell. Here's a link I found on smoke coloration and the story it can tell.

Diesel Smoke tells YOU a Story…

Edit: However, I bet the increased diesel smell will be all that much more notable over the normal smell of exhaust.

 

[jpaeye]

My 2012 L5740 does the same thing. Above about 50-55 it starts right up with minimal smoke. Below about 45-50 it fires, but spots and sputters for 10-15 seconds until it smooths over, blowing white smoke all the while. I believe your situation is normal. I have read that this behavior is due to the retarded ignition timing which is retarded to better meet emission standards.

 

[allen in texas]

My 2010 L5740 does it too. Has since it was new. I spoke to the dealer about it and he said they all do it. On really cold days 20 and below, I cycle the glow plugs 2 or 3 times. Seems to help a lot.
My dad forgets to do the glow plugs, just fires it up. Sounds like the pistons and crankshaft are going to be on the ground in a few seconds but she finally cleans up and runs. The only sputtering after that is the argument going on between me and my dad (82) about him not using the glow plugs. "boy we never had glow plugs back in '43 we just dosed 'em up with a can of ether".
"Dad, this ain't 1943, use the frickin' frackin' glow plugs!" lol
My 05 L3240 did NOT do this.

 

[Member]

Thanks very much to everyone who replied.

It looks like my local Farm and Fleet carries Power Service. I'll try some of that and see what happens.

Thanks!

--
Dan