Go BottomTractor Burning Out Glow Plugs
 | Moore
Join Date: Posts: 1 
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2001-10-06 32252
My tractor wouldn't start last. Replaced battery but still wouldn't start. Checked injectors, which were fine. Checked glow plugs, which indicated bad. I replaced all three glow plugs and it started fine. Next day went out and it wouldn't start. Checked glow plugs and they are bad again. Does anyone know what would cause the tractor to be burning out glow plugs? Thanks for your help!
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| Richard Harburn
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2001-10-06 32255
See if there is a glow plug relay that is keeping voltage on the glow plugs after the tractor has started. The relay would provide voltage to heat the glow plugs and then automatically cut off when the engine starts. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2001-10-07 32257
I'm guessing that the tractor is a reasonably modern one that was built with a 12V system rather than one converted from a 6V system. Anyway, if the glow plugs stayed on they would certainly burn out. They probably also would run down the battery and may damage the pre-combustion chambers as well. I'm curious how the plugs were determined to be bad. My repair manual gives some resistance values that can be used for tests. I believe it's also common to remove a plug and hold the base against the engine block while the pre-heat is on. If it's good, it will glow. As I understand, glow plugs don't get weak, they either work or they don't. I suppose there is a possibility that a very poorly running engine could carbon up the plugs, which would prevent them from working. However, I’d expect that operating the plugs would keep any carbon deposits burned away. Maybe somebody else has experience here. Anyway, it's really good to have a repair manual so a wiring diagram is available and proper tests are described. I would find out if a relay is present and also what the proper resistance values are, and then test the system with an ohmmeter. There's a possibility that some systems could have a resister in series with the plugs that might be shorted. In such a case, the plugs would be getting too much voltage.
I checked the wiring diagram for my Ford 1710. There is no relay for the glow plugs, but shorted contacts in the starter switch would do it. However, I believe the indicator light would function and remain lit even with the starter switch off. At any rate, if there's any doubt, I'd disconnect the battery ground cable and put an ammeter across it to check for battery drain with the starter switch off. Any reading greater than a few 10's of mill-amps indicates something that could use some attention. Mine measures 1.2ma. Glow plugs probably draw in the 10's of amps range.
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| Brent Pepper
Join Date: Feb 2002 Posts: 58 Athens Alabama
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2001-10-07 32270
I had the same problem with a Hinomoto E202(cousin to he Massey 1020). The key switch was bad. I replaced the switch and the problem went away. What kind of tractor do you have?
Brent
http://pages.prodigy.net/3peppers/index.html ....
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| Moore
Join Date: Posts: 1
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2001-10-07 32271
The tractor is a Kubota B1750. I don't think it's the switch because when you turn it to warm up the glow plugs, the indicator light lights, and when you release it and when it was started, the light goes out. So, don't believe that it's engaging them all the time. ....
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| Brent Pepper
Join Date: Feb 2002 Posts: 58 Athens Alabama
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2001-10-07 32273
Mine did exactly the same thing. On my tractor when you turned the switch to the "ON" position it automatically lit the glow plugs(a light would come on) for a certain amount of time and then turn them off(light went out). The light worked like normal but the plugs were shot. I called the local Massey dealer and disribed the problem and he told me without hesitation it was the switch. Yours could be a different problem. It is kind of hard to experinment your way to solution when when the outcome is 3 burnt out glow plugs each time you are wrong. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2001-10-08 32274
On my 1710, the glow-plug indicator doesn't light until the plugs come up to temperature--after around 15-30 seconds of pre-heat. As near as I can figure, the indicator light is hooked in parallel with the plugs. The resistance of a filament starts out low and increases as it heats. I’m guessing the way it works is that the parallel plugs/light network doesn't drop enough voltage to light the indicator until the resistance of the plugs increases with heating. At any rate, the indicator light connections do not run through the starter switch, and the indicator should function irrespective of the switch condition and light whenever the glow plugs are getting current and are heated. Of course, an indicator light circuit could be designed in other ways, and that's why it's good to have wiring diagrams. In my case, if the glow plug contacts in the starter switch were shorted, I believe the indicator light would remain on even with the tractor completely shutdown. ....
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| Bird Senter
Join Date: Jun 1999 Posts: 962 
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2001-10-08 32277
You're right, Tom, they're wired differently on different tractors. On my Kubota, turning the key "On" doesn't heat the glow plugs. You have to turn it a little further and hold it (spring loaded switch), the light comes on immediately and you just turn it further to "Start" when you think the glow plugs have heated enough (about 4 seconds if the engine is cold). ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2001-10-09 32312
Yes, I think the pre-heats on these new tractors are faster than my mid-80's Ford, although in Bird's case it may be Texas sunshine compared to my northern gloom. On my Ford, the switch is turned to the left and held until the indicator light glows and then is turned past centre to the right to start. The design on Bird's Kubota seems a bit more reliable than my Ford, even if it doesn't tell you when the plugs come up to temperature. On the other hand, with the short pre-heat required, I guess such a feature wouldn't be very helpful. However, in both cases it sounds like the indicator light would come on when ever the plugs are getting voltage, which should be a decent test if there's the possibility the plugs may be continuously on. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2001-10-09 32318
All thats needed is to check to see if the glow plugs still have power to them after starting the engine. Yes your switch could be bad. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2001-10-10 32333
Yes Art--at least I've been puttering with this subject. I'm still curious if all the plugs that were replaced were burnt open and had no electrical continuity, or if something else was wrong. I guess I'm also curious if there are any indicator light designs where the light goes out when the plugs come up to temperature. Such a design may not identify a circuit where the switch contacts are shorted and the plugs powered all the time. But as you say, the best way to check to see if something remains on is to see if it has power. Most indicator lights would do a pretty good job of that. Simple tests with a VOM would be certain if an indicator light trusted for some reason. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2001-10-10 32335
There have been many types of indicators for glow plugs used in the past. Older diesels used a resister type wire that glowed from the load to a bright red when they were at there peak. Today many use a lite on the dash that is turned on with the switch which gives you no indication of readiness of the glow plugs. These are normally faster glow plugs and only require about ten to thirty seconds versus the older style which normally took far longer to do there job. Another style doesn't go into the head at all but go in the intake manifold to preheat the air going into the engine. Those are the three most common in this field. ....
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