L48 Glow Plug

[Booth]

Hello TBN'ers

It has been years since I have posted to the forum because I was without a tractor for a while (I had a B2150HST for a dozen years but it has been about 4 years since I owned a piece of land requiring a tractor). I have a new piece of land and have purchased a L48 from a guy who has owned it since new. It came with many extras and I could not pass it up. I have driven the machine, checked all of the regular functions and am heading out to get it on Friday. But .... the previous owner called me to say that as far as he knows it does not have any glow plug function. He knows no way to run glow plugs prior to starting it. I find this bizarre to be honest, how do you operate a tractor in New England winter without glow plugs? Anyhow, I want to figure this out ASAP. The L48 controls are somewhat different than the older B2150 from my assessment. With my B2150 I recall just rotating the key an extra 15 degrees clockwise and a red light indicating that the glowplugs were on. Can anyone that owns an L48 please let me know how the glowplugs are operated.


Thanks for any help.

Jeff

 

[gwdixon]

The glow plugs are automatically operated. There are a series of relays under the dash that control the process.

On a cold day, start the tractor and the glow plug indicator on the dash will illuminate for a few seconds. It remains glowing until the tractor reaches a pre-set temperature. Sounds strange, I know. You'd think the glow plugs should be warm BEFORE starting...but, not so.

My glow plug indicator would stay on and I had to replace two relays under the dash to get it to go out once everything was up to operating temperature. That is my experience with the L48 glow plugs anyway.

EDIT: Meant to mention that my M7040 works the same way. I've only seen the glow plug indicator once in the several years of ownership and that was for about one second. But it rarely gets below freezing here.

 

[Booth]

Does that mean that when you go to start the machine on a cold day it automatically delays the start and runs the glow plugs first? I guess that is not what your answer says ... hmmm, I am confused. Admittedly I am not a diesel expert but I would have thought it could not start until the glow plugs had warmed the air inside the cylinders.

And thank you for getting back to me.

 

[tungularafishcamp]

On our L48 we turn the key one click to the right, gloplug light comes on if motor is cold after a second or two glow plug clicks off and then you turn the key the rest of the way to start. This tractor is on the Oregon coast and doesn't experience cold weather, I would assume if it did the gloplug light would stay on longer. If motor is warm light doesn't come on.

 

[gwdixon]

I think Rick has it right.

After his post my curiosity got the best of me and, since it is 50° out, I tried the first click stop on the L48 key. The glow plug light came on for about half a second and went out. A blink would have missed it. So it appears that the glow plugs automatically decide when the cylinders are warm enough to start.

I'm not sure if the engine will start before the glow plug light goes out. You'd have to have really cold weather to find out the answer.

Admittedly, I usually use the L48 in warmer weather because of winter mud in these parts. Maybe that is why the glow plug light rarely is seen.

Since I was at the barn, the M7040 was also tested...no glow plug light. Must be programmed differently.

Now, the BX2200 does have a pre-start position where the glow plugs are manually activated. That is probably how your B2150 functioned.

 

[Booth]

Thanks for the replies and investigations, I will experiment with my machine and report back. I will to watch carefully on the dash for a glowplug indicator and see what happens.

Jeff

 

[rbargeron]

The L48 glow plugs work like other Grand L's. Turning the key to the first notch, an indicator lights up for a variable length of time, longer at lower temperature. The control makes an audible buzz as it turns off, indicating the glow plugs are hot enough for starting. If its warm out the indicator goes out soon.

 

[Booth]

The L48 glow plugs work like other Grand L's. Turning the key to the first notch, an indicator lights up for a variable length of time, longer at lower temperature. The control makes an audible buzz as it turns off, indicating the glow plugs are hot enough for starting. If its warm out the indicator goes out soon.

So, I took delivery of my tractor 5 days ago and it is really awesome .... way more power, weight and thus capability over my B2150, I have been hauling 18 inch diameter oak logs over 20 feet long all over the property and lifting them out of ditches, whacking them up with my chainsaw and so on, last night I dug up a 18" diameter stump that has been in my driveway since I purchased the place, awesome machine ........ my hilly piece of land has not had any pride of ownership for 30 years as the previous owner rented it out for that long, so there are a lot of things to address. Anyhow .....

Today was cold enough to see that the glow plug indicator lamp was not lighting up at the first notch and the tractor had significant difficulty starting. Has anyone had to fix this before on their tractor?

My guess is that the temperature sensor is not working. Does anyone know if it is a thermistor, thermocouple etc? Anyone know where it is located? I have never owned a L series and it is newer than my older tractor by 10 years ... so I am pretty unfamiliar with it. I assume that when the temperature sensor is low enough that glow plugs are required that the indicator light and relays that power the glow plugs both come on together and neither seems working, so (if the temp sensor is working) then either the relay powers both the glow plugs and the indicator light or they both are broken (which seems very unlikely). I suppose if the relay was a double pole it could fire the relays and the indicator light independently. Does anyone have a repair manual for the L48 that would be willing to look at the circuit for the glow plugs, I would love to look at the schematic to see how it all works.

Any help would be appreciated.

 

[KennyV]

Hello Jeff...
If you check this : http://www.tractorbynet.com/forums/...elp-needed.html?highlight=glow+plug+controler
you will find the schematics for the glow plugs...
Your problem is Most likely going to be the "Glow Plug Controller" it supplies ground to the glow plug relay coil... KennyV

PS... you can check for power At the glow plug relay, there should be 12 volts present, (the controller turns it on by applying ground to that relay's coil)... if there is no 12 volts check wiring & fuses...

 

[gwdixon]

There are two relays under the dash, on the right side, that control the glow plugs. I had to replace both of them because of the glow plugs NOT turning off after the engine was running. The light stayed lit.

I'm glad both were replaced because they were a bear to get to. This may not be your glow plug problem but it is a suspect.

Attached is full electrical PDF parts diagrams from Messick's. They have both relays in stock. There are two diagrams with the information...new B10202 (two glow relays) and old B10201 (controller and glow relay).

DARN...TBN won't upload the PDF file...must be too large (1.7 MB). Anyway, you can go to the Messick's website or call them to download the file for yourself.

Kubota L48 | Messick's Choose "Parts Diagrams" in the red box in the middle of the page then "Electrical". It will be sent to your email.

Meanwhile I'll try some other things to try to post the pages.

 

[Booth]

KennyV & GWDixon, you guys are the best!

I purchased the tractor from the original owner, he is not really what I would call mechanically inept, he built and operated 2 fishing boats each over 50 ft long ... the guy knows about diesels and heavy equipment and so on. He bought this machine when he sold his fishing boats and went into semi-retirement ... he has always thought that the machine did not come with glow plugs .... he lives on Cape Cod where the weather is warmer and he was able to always start it in the mild winters if he left a battery charger on it .... anyway ....

When I disassembled the dash I saw a component on the right and side that said Glow Plug Relay .... that seemed like a good place to start after reading the wiring diagrams, but it was inconvenient to test it with the multimeter installed on the tractor so I thought I would unbolt it so I could get it closer to my 50 year old eyes .... when I did as it turns out there were things bolted on the other side of this sheet metal ear protruding out from the under dash structure, I had not noticed that because it was the ear is nearly under the rest of hood or whatever you call the orange sheet metal above it .... and one of those things fell loosely down into the pile of tractor infrastructure below .... when I pulled it out it was a large black plastic block that said NKG sparkplugs .... and it was NOT connected to the wiring harness. So I took it inside and googled the longest number on it ( 164156661 ) and I got right back to another thread on TBN confirming this is the glow plug controller for the L3600 .... so you can imagine I was pretty pleased to find that the controller was simply not plugged in since the machine was built .... I took it downstairs and cleaned the six spade contacts with the wire brush on my Dremel and then I plugged and unplugged it a few times into the wiring harness, and then when I turned the key .... viola ... the glow plug indicating lamp came on for about 15 seconds, then went off and when I tried to start the tractor it fired up immediately! It is cold enough and I have had enough experience with this machine to know the glow plugs are now working, that is the best!

So .... problem solved, amazing to me that the tractor has been like this since new .... hopefully the oxidation on the terminals will not come back to haunt me, yeah I know I should apply some electrical conducing grease but I don't have any and now it is time to think about trying to figure out which is the leaking hose at the connecting manifold on the backhoe .... or maybe now it is time to go back down to the woodshop and make somethign cool .... Anyhow, thanks guys!

Question for L48 experts: I might not get to fixing the backhoe leak right away. Right now the backhoe is a convenient mass of metal giving me traction for pushing snow .... if I push the hydraulic knob on the tractor out of the backhoe position and leave the backhoe connected, will it allow me to stop leaking fluid and keep the hoe on there until I fix it?

Jeff

 

[KennyV]

Hey Jeff... Glad you found a simple fix.
When it is Very cold, Give it two or three cycles of glow plugs before you start, just turn key back to off then momentary at on, repeat a couple times... works great. KennyV

 

[gwdixon]

Good news is always great to hear!

Kudos to you for troubleshooting and digging into the dash to solve the problem. Well done!