L175 When Using Glow Plugs Burning Smell

[Diesel N8]

Here's another thread for my L175, so I think something is horribly wrong with the wiring for my kubota since it does not have working lights anymore and this weird glow plug smell and also the key I put in and click 4 times to the right now only goes 2 clicks.... this was for my lights to work and they now dont ... will also update on that.

Anyways for the switch when I turn right to start it has no issues but I don't want to bump the starter for too long either to cause problems since its the oem starter, when turning this switch to the left to activate the glow plus I believe the light on the tach works and after a few seconds a putrid smell starts coming with smoke if I remember correctly...... reason being is that sometimes when its cold and I dont use the plugs it will not start quickly and I have to hold the starter but when I use the glow plugs (with that burning smell) afterwards it then starts with a cloud of black smoke and then idles normally.

 

[Roadworthy]

Did the tractor have a prior owner? My Mitsubishi did and that owner did some rewiring in the glow plug circuit. There is a voltage dropping resistance wire in my glow plug circuit. The prior owner bypassed it putting twelve volts directly to the glow plugs. Many glow plugs are intended to run on 10.5 volts - mine were. If left energized too long in cold weather the wires would begin to smoke. I bought new glow plugs, a new glow indicator, and all is well. If your glow indicator has been bypassed you will soon burn out your glow position on your ignition switch. The switch is not cheap. I just wired a separate switch for the glow plugs.

 

[Diesel N8]

Did the tractor have a prior owner? My Mitsubishi did and that owner did some rewiring in the glow plug circuit. There is a voltage dropping resistance wire in my glow plug circuit. The prior owner bypassed it putting twelve volts directly to the glow plugs. Many glow plugs are intended to run on 10.5 volts - mine were. If left energized too long in cold weather the wires would begin to smoke. I bought new glow plugs, a new glow indicator, and all is well. If your glow indicator has been bypassed you will soon burn out your glow position on your ignition switch. The switch is not cheap. I just wired a separate switch for the glow plugs.

Yes it did have a PO it has 1700+ hours I believe, and I can see some shady things done to it such as some red rtv type seals around the tranny and brake parts and also steering box.... I am not very good with wiring but if I provide some pics maybe that can help determine the issue?

 

[Oil pan 4]

If you get a funny smell while glow plugging it just about always means you're melting a wire somewhere for some reason.
Usually the wire is worn through some where and your are short circuited to ground when you hit the glows.

 

[GeoHorn]

Not a Kubota... But my previously-owned JD-powered compactor also emitted a burning smell and smoke when I first-time attempted to use the glow-plugs this winter.
Later on, I was checking out the reason the low-oil-pressure “beeper” (sonalert) never sounded with the key “on” but the engine not running, nor the hour-meter working. (They share a ground wire which was broken.). So I replaced the ground wire.
When I next checked under the hood...that new ground wire’s insulation was “bubbled” and burnt. A-Ha! The smell and the smoke source! Pressing the glow-plug switch would cause that ground wire to become incandescent!

Turns out some previous owner had mis-wired the system to bay-pass the glow-plug relay/solenoid. By scrutinizing the electrical schematic I was able to correct the system to original status, which required me to replace (again) the ground wire and to install a replacement glow-plug relay/solenoid and wire it properly.
Now all works correctly, oil press-warning works, hour meter works, and glow-plugs work without burning smells or smoke.

Be wary of previously owned equipment modified by ignoramus’s.

 

[Dave_eng]

L series of that era have two different wiring schematics for their GP's

L185 and L210 have GP's wired in series.

L175, L225 & L260 have GP's wired in parallel.

It is not uncommon for an owner to connect the GP's incorrectly.

GP's themselves would not smell.

Electrical wiring would smell if overloaded.

Dave

 

[Russell King]

I also believe that the glow plugs are powered while the switch is in the start position. I know that on my l185 they are and NIW has commented that fact on other threads.

Which then brings into doubt that the glow plug indicator is always in the circuit. Which means they see 12 volts in the start position?

If someone that understands the schematic or wiring can comment on that I would appreciate the clarification on how the circuit works. I may be able to post a schematic if needed.

Anyway you can disable the starter by not pushing the clutch down and see if the burning smell occurs in the start position also, as I understand the circuit.


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[Oil pan 4]

I also believe that the glow plugs are powered while the switch is in the start position. I know that on my l185 they are and NIW has commented that fact on other threads.

Which then brings into doubt that the glow plug indicator is always in the circuit. Which means they see 12 volts in the start position?

If someone that understands the schematic or wiring can comment on that I would appreciate the clarification on how the circuit works. I may be able to post a schematic if needed.

Anyway you can disable the starter by not pushing the clutch down and see if the burning smell occurs in the start position also, as I understand the circuit.


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Yes I was looking at that on mine today, looks like the old tractors run the glow plugs through the "glow plug cigarette lighter" during glow plug warm up and it runs full power straight to the glow plugs when cranking.

Also the glow plugs are ran in parallel, through 1 wire. I may rewire mine to run a 12 gauge wire to each plug, looks like they are both fed by a single 12 gauge wire from the factory.
The glow plugs do run in series with the "glow plug cigarette lighter" when warming up the glow plugs.

 

[Dave_eng]

I also believe that the glow plugs are powered while the switch is in the start position. I know that on my l185 they are and NIW has commented that fact on other threads.

Which then brings into doubt that the glow plug indicator is always in the circuit. Which means they see 12 volts in the start position?

If someone that understands the schematic or wiring can comment on that I would appreciate the clarification on how the circuit works. I may be able to post a schematic if needed.

I can answer your questions regarding the GP wiring and logic.

The key to how the GP's work in various key positions lies in terminal 17 on the key switch. You find two wires connected to that terminal. One wire from the output of the glow indicator and a second wire going directly to the GP's.

The main power supply to the key switch comes in on Terminal 30.

When the key is turned to preheat, power flows from terminal 30 to terminal 19 which feeds the GP indicator. Power flows out of the GP indicator back to terminal 17 on the key switch. At this point terminal 17 is only serving to connect two wires together. Power out of the GP indicator and power out to the GP's. In this preheat position, all power seen by the GP's flows through the GP indicator which is a form of resistor.

When the key switch is turned to start, power flow from terminal 30 to terminal 50 which is the starter solenoid and the engine begins to crank.

Power also flows from terminal 30 to terminal 17 which is the terminal feeding the GP's. Now the GP's are receiving power that does not flow through the GP indicator.

One's first reaction is that the GP's are now receiving 12 volts. Sort of true until you accept that the cranking starter has drawn down the battery voltage so in reality the GP's actually see the usual 10.5 to 11 volts.

Hope this makes sense. Please ask questions if needed.

Dave

 

[Russell King]

Ok that makes sense about the voltage drop reducing the apparent voltage to the glow plugs. But to be argumentative then if you don’t push the clutch pedal down and the safety switch won’t let the starter draw voltage then the glow plugs will see a full 12 volts.

So I assume it is bad to do that. I guess I will use a volt meter to see exactly what voltage shows up in both situations. I have only seen the indicator glow one time when it was really dark. Otherwise I can not see it even with a brand new indicator installed.

Thanks for the through explanation of the circuit.


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[Dave_eng]

Ok that makes sense about the voltage drop reducing the apparent voltage to the glow plugs. But to be argumentative then if you don’t push the clutch pedal down and the safety switch won’t let the starter draw voltage then the glow plugs will see a full 12 volts.

So I assume it is bad to do that. I guess I will use a volt meter to see exactly what voltage shows up in both situations. I have only seen the indicator glow one time when it was really dark. Otherwise I can not see it even with a brand new indicator installed.

Thanks for the through explanation of the circuit.


Sent from my iPad using Tapatalk

Seeing you have a L185, let me remind you that your GP wiring at the tractor is different than the norm. This results in a different reaction with the glow indicator as the GP's warm up

From one of my earlier posts:

L series of that era have two different wiring schematics for their GP's

L185 and L210 have GP's wired in series.

L175, L225 & L260 have GP's wired in parallel.

Some series wired models ( not certain if L series is included) have an additional resistor in a metal box near the base of the steering column.

Plse post a photo of your tractor's GP wiring at the engine. Expect to see one of the GP's with a ground wire attached to the block.

Dave

 

[GeoHorn]

Ok that makes sense about the voltage drop reducing the apparent voltage to the glow plugs. But to be argumentative then if you don’t push the clutch pedal down and the safety switch won’t let the starter draw voltage then the glow plugs will see a full 12 volts.

So I assume it is bad to do that. I guess I will use a volt meter to see exactly what voltage shows up in both situations. I have only seen the indicator glow one time when it was really dark. Otherwise I can not see it even with a brand new indicator installed.

Thanks for the through explanation of the circuit.


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When you do that.... you’ll notice that when you activate the glow plugs that THEY will draw down the voltage also.
My JD machine has a GP that is provided a full 12v but placing a voltmeter on the GP terminal when the switch is activated only indicates 6.5 volts due to the GP drawdown. Disconnecting the wire from the GP and it will indicate 12v.

 

[Diesel N8]

So I definitely know the wiring is messed up.... I will update with as many pics possible soon... I got the bolts off the tach one time and that shifts some wires behind it and it causes for the oil light and the other light to turn on even without the key in.
Also I tryed to start the tractor but it wouldnt turn unless I messed with the whole tach assembly and the wires would move somehow and cause this clicking noise. Anyways I will send pics your way soon

 

[Oil pan 4]

Wired melted all to hell?
Mine were.

 

[AmusingLisa]

Yes it did have a PO it has 1700+ hours I believe, and I can see some shady things done to it such as some red rtv type seals around the tranny and brake parts and also steering box.... I am not very good with wiring but if I provide some pics maybe that can help determine the issue?

Hey Diesel - I am not too far from you! Hoping you might have a parts source. I need a new or replacement glow plug switch. I would sure appreciate any resource you might know

 

[Russell King]

The dealer should be able to get the switch