Glow plug operation

[rnbrn21]

I own a BX24 and I think there is something wrong with the glow plug operation. I want to start by saying that the tractor starts and runs fine, but I don't think the glow plugs are operating correctly. I started it yesterday at about 25 Deg.F and when I turn the key switch to the first setting I get the clicking but the glow light indicator does not come on. When I turn over the engine the glow plug indicator light comes on while I'm cranking and until I release the key switch after it starts. It takes about 15 seconds for it to start and there is black smoke for a short time after it starts. I've owned this tractor for about 2 years now and I distinctly remember the glow plug indicator light coming on as long as I had the switch in the prestart position. Any input would be appreciated.

Ron Brown
Rochester, NY

 

[uglyboywith11fingers]

Ron, if you hold the keyswitch about half-way between ON and START, the glow plugs operate... you'll notice the indicator on.
In very cold weather, I usually hold my BX24 there for about 10 seconds or so, then turn further to engage the starter. It always starts right away, with just a little puff of black smoke.
There really is no 'prestart' detent, at least not on my BX24.

Pete

 

[timswi]

Ron, if you hold the keyswitch about half-way between ON and START, the glow plugs operate... you'll notice the indicator on.
In very cold weather, I usually hold my BX24 there for about 10 seconds or so, then turn further to engage the starter. It always starts right away, with just a little puff of black smoke.
There really is no 'prestart' detent, at least not on my BX24.Pete

Exactly. My BX23 has no detent either, just turn the key until you feel the start position coming on and hold..My glow plugs come on every time even after 10 years. You'll get a small belch of black smoke but shouldn't be excessive.

 

[rnbrn21]

I have to Thank You for your responces. I reread both responses and realized what you were saying. I could have sworn that the glow plug indicator came on with the key switch in the on position. I just went out and tried moving the switch between on and start and behold the glow plug indicator came on. I'm glad to be wrong because it means there is nothing wrong with my tractor. I also learned by watching a YouTube video that if after starting your tractor if it is running really rough you can move the key switch back to the glow plug on point to give the engine a little more warmth to smooth it out. I haven't tried it though.

 

[handymantim]

My B26 owner's manual has the following guidelines for holding the switch in the glow plug position (between ON and START, glow plug light lit up) prior to start:

2-3 seconds when over 32F
5 seconds for 23F to 32F
10 seconds for 5F to 23F

Since it doesn't have additional guidance past 10 seconds, I'm guessing past 10 seconds either doesn't get the glow plugs any hotter OR gets them too hot and is therefore bad for them.

 

[wrooster]

I also learned by watching a YouTube video that if after starting your tractor if it is running really rough you can move the key switch back to the glow plug on point to give the engine a little more warmth to smooth it out. I haven't tried it though.

There is no reason to ever do this.

wrooster

 

[Toyboy]

There is no reason to ever do this.

wrooster

Why? I find it starts faster that way.

 

[PILOON]

Cycling twice B4 starting is not a problem but while running could cost you a glow plug or two.
Glowing while running will add additional heat to the plug filament all while vibrating.
Think light bulbs; much more fragile when hot.

 

[MHarryE]

Not sure of the durability of the glow plugs Kubota uses but the very good glow plugs used in diesel autos and at least some tractors are pre, start, and post heating. The computer on those engines controls heating until the engine is running smoothly. Remember the glow plug in a combustion chamber is not an air heater. It instead provides a hot point that will start the combustion burn before compression only gets it to that temperature. If it was heating air, that air is gone the first exhaust stroke. So when you crank over the engine the glow plugs trigger combustion, but without power they quickly cool but by that time, the designers hope the engine is running. BERU glow plugs heat up to 180 seconds post heat.

 

[David Devuono]

My 1986 or so B4200 calls for 15 seconds on the Glow plug above freezing and 30 seconds below freezing. It may take two to three 30 second shots before it will run in winter. So for 25+ year old Glow plugs, they are pretty robust.