L210 Glow Plug Resistor

[Dave_eng]

I'll have to beg to differ on that one Dave. It's possible a plug can be shorted to ground internally, and still have a circuit. In that case, if it were the first plug, then only it would operate, as no voltage would get to the second plug. Also it could be shorted internally and be open circuit, and in that case, when the connection was made originally to the bottom terminal, no current would flow in either plug, even if the second plug was OK, as it would go straight to ground, or if it was the second plug, then only the first plug would work. It's worth checking when you aren't at the location.

I guess the internal short is possible but i have never seen one experience that condition when it is the visible electric element type.

What do the GP's of the newer style cost?

Dave M7040

 

[jwage]

Ok I tested each of them individually on the tractor wiring out of the block, they both smoked for a second and I started to see it get red after 10 seconds and I stopped.


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[Dave_eng]

Ok wired it up like this on both of them and I got .3 and .5

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Trying to find spec's but not having much success on the internet.

Calling this NGK web site using the posted number at the right time of day may get you someone with either a replacement of the same design or a replacement of newer design.

Calling Messicks for a replacement of newer design may be a big saving. A GP for a 1980's B7100 is $11.00 compared to over $100 for the original L210 type of GP

Sorry I cannot do more for you tonight. Its midnight here and I must get up early.

Dave M7040



https://www.ngk.com/product.aspx?zpid=16109

 

[100 td]

6 BPD or 8USD plus postage, no idea if they post, but worth a shot.
If not, it appears 2 x OEM landrover plugs are available at 34USD delivered
or 4 x 12 volt plugs for $49USD delivered

 

[100 td]

http://www.ebay.com/itm/302231183457
http://www.ebay.com/itm/221573257129
You would have to confirm size and thread to be sure.

 

[100 td]

Ok I tested each of them individually on the tractor wiring out of the block, they both smoked for a second and I started to see it get red after 10 seconds and I stopped.

Looks like you may not need new ones at this stage............ They do need to get very red, and it appears they will, I expect standard warmup is 30 seconds for your tractor, check your manual.

 

[jwage]

As far as I can tell, they seem to work. I guess I should replace that aluminum metal wire connecting the two glow plugs with a better copper version and try to see if they work again and it starts easier.

 

[100 td]

The aluminium will work for now, if its clean, sand the connection points down so they are nice and shiny. You will also be able to check if it's aluminium or not.

 

[100 td]

You dash glowplug indicator should also glow red

 

[jwage]

Success! First I tested each one independently with my scrap copper wire connecting to the wiring on the tractor, and each one worked by itself. Then I tested them one at a time again except with the aluminum wire running to the ground. This also worked. So I put it all back together connecting both glow plugs with the aluminum wire (still not in the engine block) and it worked. I took it a part to install in the engine block, mounted all the wires, no dice. So I loosened the top nut and pulled the ring terminal tight up against the threaded bolt and tightened the nut and it worked, dash indicator got hot, I turned it over and it started right up in about 3 seconds. Now I sleep. Thanks again for the help guys!

 

[100 td]

Gr8! Dave_eng to the rescue with great pics.

 

[Dave_eng]

I re read the WSM for the L210.

Each GP sees a voltage drop of 1.5 volts while 40 amps passes through it.

Therefore using the formula Power in watts = Voltage drop x amps, the glow plugs each put out 60 watts of power.

Using the formula Power = (Voltage x voltage)/resistance

60 watts= 1.5volts x 1.5 volts/Resistance in Ohms

Ohms are = 0.0375 ohms for each glow plug

Since they are now working which is great news, the above is just something to save for the future.

jwage. You are to be commended for sticking to a problem until there is a solution. Many would have given up!

Dave M7040

 

[D2Cat]

jwage, sounds like you got that problem whipped. You got some good help and by the pictures were able to communicate. Good work--thanks to Dave_eng and 100 td! Persistence always wins.

 

[jwage]

Thanks everyone! It was very fun. I work on systems and software engineering for my day job, not exactly the same thing, but many similarities in how you problem solve and troubleshoot complex systems with many different parts. Persistence, process of elimination, lots of reading, reading more, double and triple checking things, etc. are all the same in my day job.



I feel like at a high level I understand the principles/physics of electrical, etc. but I am still learning all the lingo and how to communicate and interpret things. The more I know, the more I'm willing to mess with comfortably. You'll probably see more from me once I decide what I am going to try and fix next.

Edit: gave it another start this morning and it started even better this time. Took about 1 second before it was running. Woohoo!

 

[100 td]

Just a note on the glow plug circuit design for others following. Whilst Kubota call their key switch/dash glow indicator circuit a "glow controller", it's a very basic one at that, but it does the job. The circuit provides power through the key switch, then through the dash indicator(resistor), then the ballast resistor (voltage dropping or current controlling resistor), then through each glow plug in series. The total (additive) resistance of that circuit controls the current flowing through it.
When turning the key to heat, the same current flows through all components, which heats up the glow indicator on the dash, the resistor and the glow plugs. If any of these components has a bad connection or is open circuit, the entire circuit fails.
Therefore, if your dash indicator does not become red, then both your glow plugs are not working.
When the key is turned to start, the dash indicator(resistor) is bypassed, and current flows through the ballast resistor and both glow plugs. The reason this is done is so when you are cranking the engine with the starter motor, it draws a heavy current and reduces the available voltage from the battery to the glow plug circuit. So now a lower voltage is available to the glow plug circuit. So by removing the dash indicator(resistor), there is less resistance in the circuit, and even though the battery voltage will be less, the glow plug current will be similar due to less resistance in the circuit and still function correctly.

 

[D2Cat]

100 td, in your example above, if the last glow plug in the circuit was not functioning (burn out) would the glow plug circuit still function as normal, just not getting heat to one cyl, since it was the last one?

 

[100 td]

100 td, in your example above, if the last glow plug in the circuit was not functioning (burn out) would the glow plug circuit still function as normal, just not getting heat to one cyl, since it was the last one?

No, as this particular circuit is a SERIES circuit, all items are in a continuous string, break any part of that string and it all fails.
(Excepting in the case if the first plug outgoing connection was damaged or shorted to ground, or the second plug incoming terminal shorted to ground when it burnt out. Not a very common scenario, but a possibility. Installation of extra washers and terminals that are too big on the glow plugs can also short to ground.)

Heat selected on switch
Battery - Key switch - Dash indicator - Ballast Resistor - Glowplug - Glowplug - Ground connection

Start selected on switch
Battery - Key switch - Ballast Resistor - Glowplug - Glowplug - Ground connection

On a later model PARALLEL circuit, one glowplug can fail and the others keep working as supply is connected to each glow plug individually and each plug goes to ground
BAT - Key switch - indicator >
|-GP- Ground connection
|-GP- Ground connection
|-GP- Ground connection

As an additive, many people come across glowplugs in different machines, and there are many different ways of controlling them. You may find engines with ballast resistors in circuit supplying parallel glowplug circuits, the glowplugs may be rated at 7 volts. An electronic glowplug controller will switch the glowplugs on with 12 volts for a short time, determined by a temp sensor in the coolant, then it will switch the power through the ballast resistor for a remaining time interval, so the plugs don't burn out. This achieves a quicker heat up time. Also the plugs will remain on after the engine has fired for a predetermined time to help smooth the engine when cold etc. In this particular case the ballast resistor is located in the inlet manifold.

Later model direct injection engines use "toasters" (heaters) in the inlet manifold to heat the air after start to reduce emissions and make a smoother engine when cold. My landcruiser toaster draws ~150 amps.

 

[Dave_eng]

jwage

A lot of your work on your tractor has involved cleaning up electrical connections.

I was thinking the bolts, washers, lock washers and nuts associated with your resistor for the GP's would be much more durable if they were stainless steel instead of the plated fasteners you used.

As you have seen, there is a lot of heat built up in the resistor and this will break down the plating over time and you could have a poor electrical connection some time in the future.

Dave M7040

 

[jwage]

Thanks Dave. I will do that. Sounds like a good idea


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[bigbull15]

So after much searching and trying to make the resistor and trying to find a glow plug, I decided to convert to pencil style glow plugs and run them with a Ford Solenoid. I have to say that was a chore, but it worked great! It pops off a heck of a lot easier. I know it's not original but I had to get it going.

Birddog25, any chance you could give the info on the pencil type glow plugs you ended up using? For that matter, any other helpful information on updating your GP system would be great appreciated.

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