Cold weather start, with glow plugs and block heater. Why does my tractor not start at minus 20 C?

[Egon]

All the block heaters that I have installed are just pure resistive heating elements,
no control whats so ever. Easiest way to ruin one is run it with no water surrounding it.
Less then 5 minutes to element burnout.

They look like that but they are temperature regulated by the way the element is made. The element has to properly oriented when installing for it to work.

 

[lpakiz]

I still doubt that.
Procure a block heater and immerse it in a small container of water (a soup can, small cooking pan) and plug it in. Pretty sure it will boil the water, and boil it hard, until it evaporates enough water to expose some part of the element, then the element will burn out.

 

[Egon]

I still doubt that.
Procure a block heater and immerse it in a small container of water (a soup can, small cooking pan) and plug it in. Pretty sure it will boil the water, and boil it hard, until it evaporates enough water to expose some part of the element, then the element will burn out.

I still doubt that.
Procure a block heater and immerse it in a small container of water (a soup can, small cooking pan) and plug it in. Pretty sure it will boil the water, and boil it hard, until it evaporates enough water to expose some part of the element, then the element will burn out.

Give that a try and let us know what happened. Make sure the heater is immersed in the proper orientation.

There are many misconceptions on how a block heater works including non transfer of heat to the oil in the oil tank.

 

[lpakiz]

I tried to edit to add another paragraph and lost the whole thing!
I wanted to add that the element position has more to do with hot water rising (element loop should not face down) and especially, the element cannot touch any metal engine parts. That's why there are dozens of element shapes-to clear internal engine parts.
I still stand by the "full on or full off" part of my previous post. If there is added resistance when the water gets hot, a clamp-on ammeter on one of the supply legs would indicate less amps.

And if that were the case, an electric water heater wouldn't need a thermostat-just design the element to kick out at 130 degrees. They don't. When the thermostat fails "ON", the water gets so hot the pressure relief valve starts to emit steam.
Now, the block heater will never get so hot as to boil, because the heater is probably 800 watts or so for a big one. (I was shop foreman for a trucking company and we used 1500 watt heaters in our 855 CID Cummins. In Wisconsin).
The element in a very well insulated water heater tank is 4500 watts, if I remember correctly. Not much heat escapes, so the water heater boils if not shut off by the thermostat or the increasing resistance of a heated element.
The blocks on our tractors loose heat much faster, so fast that it's doubtful if the exterior of the block gets warmer than 100 degrees, more than a few inches from the location of the heater. But even 80 degrees around the cylinders equates to a warm summer day, when my tractor starts very well without heat.

 

[LouNY]

Heaters by Kat's
No place in their literature will you find any information on self regulating block heaters.
You can find thermo cubes which are temperature switches, you can find timers, but no mention of regulated.
Block heaters are on/off.

 

[lpakiz]

I do believe there are some models of TANK heaters that incorporate an internal thermostatic switch which will turn the element ON or OFF, but it doesn't regulate (vary) the current flow.

 

[Egon]

Well, tell me how a self regulating heat tape works.

 

[Mattsy Fergy]

 

[CalG]

Just to add a couple of deviations to the "Cold starting" issue.

Firstly

The Kubota B7200 has a compression release that is sometimes described as an aid to cold starting.
Presumably the benefit is getting the pistons all moving at a good clip prior to a need to do the real work of compressing air and making heat.
My own experience hasn't drawn conclusions on this idea. The engine is a hard starter when cold without the glow plugs, starts right up with glow, and the battery condition is key . Either way! ;-)

Second

Injected fuel is cold, with any vaporizing fuel chilling the intake charge even more. Countering the heat produced via compression.

Cranking the cold engine while holding the fuel cut off closed may offer some "accumulated" chamber wall heating that could benefit the combustion once fuel is allowed to be injected.

desperate times take desperate measures ;-)

 

[Mattsy Fergy]

With a block heater, if the temp gets above the motors thermostat setting, it will open and allow the hotter water to go to the radiator, pulling cooler water into the block thus cooling it. So the coolant will never go above whatever the thermostat setting is.
This is not likely to happen since the mass of cast iron will bleed heat off faster than the block heater can heat it.