Block Heater Surprise

[npalen]

I left the block heater plugged in the other day while working on my B9200 Kubota. I was working on the hydraulics in the shop at 55-60 degrees (F) and wanted to avoid using the glow plugs each time starting the engine. I do have a large exhaust fan but the block heater seems to minimize the smoke at startup as well as the wait time for glow plugs. (it's a 30 year old tractor so likes the heat)
What surprised me is, after having not started the engine for a while, how warm everything was. The engine valve cover was too hot to touch for more than a second. This is with a 430 watt block heater. Just surprised me how hot it was given all the area in which the coolant could give up heat.

 

[Dave M7040]

My tractor, a M7040 is larger and its glow plugs operate differently than yours but let me tell you of my experiences with block heaters and glow plugs.

My tractor sits in a shed without a door so it is as cold as outdoors which can go to as much as -40F.

The shed is 300 feet from my home so a came up with a way to turn on the block heater from inside my home.
Originally, I tried the wireless devices advertised for such jobs but found they do not work below a moderately cold temp. Very cold and they don't work. The companies admit this and if read carefully their literature says so as well.

I installed a contactor, really a relay for 120 volt circuits with a 24 volt AC coil to engage the contacts. This contactor turns on the power for the receptacle for the block heater. Also plugged into this receptacle is a blue outdoor spot light which is pointed at my home.

I got a 120 to 24 volt control transformer for approx $20. The contactor was $22.

For years I had a two conductor wire lying in the long grass running from my home to the tractor shed.

This year I buried a black poly water line and fished a 14 2 house wire in the pipe to carry my 24 volt AC control signal to my home. This wire was actually the cheapest and had minimal voltage loss when powering the contactor.

I can either flip a switch or turn a spring wound timer to activate the contactor and hence the block heater. Seeing the blue spot light come on lets me know the heater is working.

After an hour or 1.5 hours of block heater, the tractor is ready to go. However, because the engine block is warm, the electronic sensor which activates the glow plugs, thinks it is warm outside and the glow plugs do not come on. As the engine cranks, and it does so easily because the oil etc is warm, it is inhaling -40F air and it does not fire up easily.

The dealer mechanic told me of an undocumented work around where if you put the shuttle shift in forward and turn the key to start position. The glow plugs are heating although there is no indication on the dash. I count to ten, put the shuttle in neutral and the tractor fires instantly.

Dave M7040

 

[npalen]

That's interesting. Wonder how many folks could use this workaround? Looks like it would be an easy fix if the electrical engineers considered this scenario.

 

[Gordon Gould]

My tractor, a M7040 is larger and its glow plugs operate differently than yours but let me tell you of my experiences with block heaters and glow plugs.


After an hour or 1.5 hours of block heater, the tractor is ready to go. However, because the engine block is warm, the electronic sensor which activates the glow plugs, thinks it is warm outside and the glow plugs do not come on. As the engine cranks, and it does so easily because the oil etc is warm, it is inhaling -40F air and it does not fire up easily.

The dealer mechanic told me of an undocumented work around where if you put the shuttle shift in forward and turn the key to start position. The glow plugs are heating although there is no indication on the dash. I count to ten, put the shuttle in neutral and the tractor fires instantly.

Dave M7040

My L3010 is the same way. It actually starts much easier (quicker really) but runs a little rough for a while w/o the block heater but of course this is tougher on the motor with the cold oil and rough start up. But with the block heater the starter has to crank a looooong time before it starts so I worry about the starter. I always wondered if there was a way to make the glow plugs run when the motor was warmed by a block heater.

Can't wait to try your suggestion - thank you very much.

gg

 

[npalen]

Awesome!

 

[Thomas]

If you have mice you may want to check engine area and air filter.

 

[Gordon Gould]

If you have mice you may want to check engine area and air filter.

What are you trying to say Thomas - You think mice could cause this ?? Can you explain a little to help me understand.

In my case w/o the block heater at say -5* F the automatic glow plug timer goes on for 10 seconds or so and the motor catches and starts roughly on the first or second crank.

If I use the block heater to warm things up first the automatic glow plug timer only goes on for a second or less. It cranks over easy but takes a long time before it starts. When it does start it is smooth.

gg

 

[rScotty]

The dealer mechanic told me of an undocumented work around where if you put the shuttle shift in forward and turn the key to start position. The glow plugs are heating although there is no indication on the dash. I count to ten, put the shuttle in neutral and the tractor fires instantly.
Dave M7040

So how does that work? It sounds like there is a workaround way to bypass the the sensor that keeps the glow plugs from being turned on even for starting whenever the temperature is high enough that glowplugs aren't needed. But if the circuit can turn on the glowplugs with the key on and the tranny in forward......and without any indication on the dash .......then does that mean that the glow plugs are normally on all the time the engine is running? Or if not, what turns them off?
rScotty

 

[Rocky J]

I do not have one of the tractors but would guess it is a feedback, maybe the back up alarm searching for a ground and found it through the glow plug circuit, once the engine starts the DC current reverses and stops coming out of the battery and back into the battery stopping the current from feeding the glow plugs when it is running , a diode somewhere would explain the theory. When I was a child we would play in the family Ford Galaxy and if we turned on the four way flashers and step down on the brake we could listen to the radio with out the keys.

 

[npalen]

When I was a child we would play in the family Ford Galaxy and if we turned on the four way flashers and step down on the brake we could listen to the radio with out the keys.

That's hilarious!

 

[Rustyiron]

But with the block heater the starter has to crank a looooong time before it starts so I worry about the starter.
gg

This is a little diesel trick that I've used, not on a tractor, but I've pointed a heat gun (hair dryer would work) into the air cleaner (while cranking) and it was the difference between starting or not.

 

[CobyRupert]

So how does that work? It sounds like there is a workaround way to bypass the the sensor that keeps the glow plugs from being turned on even for starting whenever the temperature is high enough that glowplugs aren't needed. But if the circuit can turn on the glowplugs with the key on and the tranny in forward......and without any indication on the dash .......then does that mean that the glow plugs are normally on all the time the engine is running? Or if not, what turns them off?
rScotty

I'm interested to see what the feedback is.

Not that the "undocumented work around" doesn't exist or is impossible, it just seems highly unlikely that any sane designer would design something that way.
Especially putting extra secret features on a system that is lacking features to begin with.

Why would a glow plug circuit operate off the shuttle shift position?
Why would somebody circuit the glow plug indication lights so they don't indicate if they're operating?
(Think about the extra work it would take so that your turn signal indication lights don't work...but only under certain conditions)

 

[Gordon Gould]

This is a little diesel trick that I've used, not on a tractor, but I've pointed a heat gun (hair dryer would work) into the air cleaner (while cranking) and it was the difference between starting or not.

I have heard that but I have never tried it because it always eventually starts. But you got me thinking and maybe it would be a good thing to do. I do have a heat gun.

gg

 

[Gordon Gould]

I'm interested to see what the feedback is.

Not that the "undocumented work around" doesn't exist or is impossible, it just seems highly unlikely that any sane designer would design something that way.
Especially putting extra secret features on a system that is lacking features to begin with.

Why would a glow plug circuit operate off the shuttle shift position?
Why would somebody circuit the glow plug indication lights so they don't indicate if they're operating?
(Think about the extra work it would take so that your turn signal indication lights don't work...but only under certain conditions)

I will try it the next cold morning we have and let you know what happens.

I agree that it is doubtful that it is a designed in feature. More likely some kind of back-feed situation missed by the engineers. There must be a fail-safe mechanism to make sure the glow plugs are unpowered if the starter engages. The shuttle shift also has a safety switch on it so the starter won't crank if it is not in neutral. It is a stretch but a common link maybe ??????????

The thing I wonder about is this: the glow plugs must take a fair bit of currant being heaters. If enough currant is flowing to heat them in an unintentional circuit path it may not be healthy for those components to carry that much currant. Assuming this trick is a design flaw rather than a design feature.

gg

 

[CobyRupert]

How about this for a scenario: Electronic temp sensor disables glow plugs during pre-start when warm, but when key goes to start position the temp sensor is bypassed so that glow plugs are energized to counteract cold air and fuel entering cylinder for as long as it takes to start (when key in start position).
Thus by putting shuttle shift out of neutral you are bypassing the temp sensor, energizing the glow plugs, but not allowing it to start, thus getting a sustained glow plug application.

...but this would mean glow plugs momentarily come on every time you start the tractor (key in start position), even in summer? Could this be?

 

[Dave M7040]

So how does that work? It sounds like there is a workaround way to bypass the the sensor that keeps the glow plugs from being turned on even for starting whenever the temperature is high enough that glowplugs aren't needed. But if the circuit can turn on the glowplugs with the key on and the tranny in forward......and without any indication on the dash .......then does that mean that the glow plugs are normally on all the time the engine is running? Or if not, what turns them off?
rScotty

Scotty

What I observed was my local Kubota dealer with lots of machines parked outside when it was very cold was starting them and moving them for snow clearing.

The machines were firing immediately which seemed unbelievable good luck and then I questioned the mechanic and learned the work around. Sometimes they will do the work around a second time.

The Shuttle shift has to be in forward and the key turned to the START position not to ON. Then the glow plugs activate with no dash indication.

I cannot think of another time when you would have the shuttle in forward and the key turned to start.

I don't profess to understand how it works but for certain I experience it working.

Dave M7040

 

[npalen]

Is there a similar procedure on the hydrostat tractors?

 

[Dave M7040]

Is there a similar procedure on the hydrostat tractors?

I dont have the model knowledge to understand the tractors you are referring to.

What year and model are you talking about?

I was just looking further and it appears that your glow plugs are not part of an electronic logic box which determines their operation.
You should have the best of both worlds in that you can run the GP's when and for how long you want.

Dave M7040

 

[npalen]

I was just wondering, if this is something that was actually intended by the designer, whether there was something similar on the hydrostat models. Yes, I knew that my antique is "electronically challenged" but just wondering about the newer hydrostat tractors.
The hazard flasher is about the only electronics on my '87 Kubota. Well maybe the voltage regulator also. lol

 

[RoyJackson]

If you have mice you may want to check engine area and air filter.

Very true...happened to me. The surprising thing is the mice didn't get into the tractor's air cleaner...they built their nest into my daily driver truck air cleaner. That nest caused the truck to shut down on a trip to Connecticut (about 70 miles from home).