Strange blown fuse while digging stumps

[CalG]

I've spent the past few days removing a couple of stumps that have been a PIA for some number of years since the trees were felled. The exposed stumps of both appeared to be well decomposed, but that turned out to be an illusion. The little Hurlimann 435 had it's work cut out! (But both stumps are now out back on the "stump pile" ;-)

To the point,
Though most of the real digging was done in the lowest of the 12X12 gear box, In effort to speed soil burden relocation, 3rd gear would be selected for travel to and from the nearby dump pile. Late in the afternoon, I went into the stump diggings in that same 3rd gear and promptly stalled the engine. No issue said I, a simple restart, and back out. But NO! The turn of the starter key did nothing! Nadda, Not even a panel light. What the heck!??
Blinkers? OK, Work lights? OK, Headlights? OK, Flashers? OK. But no starter or engine heater indicator lamp.
Suspecting a loose wire at the starter switch, I removed the instrument cowl , which requires removal of the steering wheel! Jeesh! Who designed that? All connectors good.
But a 30 Amp fuse was blown.

Hmm... What would blow the starting system fuse ?
Fortunately, I had a spare in my stock of things. But now I'm worried ...
Was it a freak coincidence of glow heaters turned on while the starter motor was engaged?
I usually wait until the glow light times out to activate the starter. But in this incident, I reached for the key only moments after the engine bogged.

Any ideas?

I'm going to purchase a couple more fuses (30amp) to have on hand...;-)

 

[Williy]

Maybe a shorted wire? I would check all wires going
to and from that 30 amp fuse

willy

 

[rScotty]

I've spent the past few days removing a couple of stumps that have been a PIA for some number of years since the trees were felled. The exposed stumps of both appeared to be well decomposed, but that turned out to be an illusion. The little Hurlimann 435 had it's work cut out! (But both stumps are now out back on the "stump pile" ;-)

To the point,
Though most of the real digging was done in the lowest of the 12X12 gear box, In effort to speed soil burden relocation, 3rd gear would be selected for travel to and from the nearby dump pile. Late in the afternoon, I went into the stump diggings in that same 3rd gear and promptly stalled the engine. No issue said I, a simple restart, and back out. But NO! The turn of the starter key did nothing! Nadda, Not even a panel light. What the heck!??
Blinkers? OK, Work lights? OK, Headlights? OK, Flashers? OK. But no starter or engine heater indicator lamp.
Suspecting a loose wire at the starter switch, I removed the instrument cowl , which requires removal of the steering wheel! Jeesh! Who designed that? All connectors good.
But a 30 Amp fuse was blown.

Hmm... What would blow the starting system fuse ?
Fortunately, I had a spare in my stock of things. But now I'm worried ...
Was it a freak coincidence of glow heaters turned on while the starter motor was engaged?
I usually wait until the glow light times out to activate the starter. But in this incident, I reached for the key only moments after the engine bogged.

Any ideas?

I'm going to purchase a couple more fuses (30amp) to have on hand...;-)

Cal, there is no mystery there. If you add up the amps for the glow plugs and starter it makes perfect sense that it would easily blow a 30 amp fuse. It would only be a problem if it didn't do that.

So no foul and no harm done. It's just your tractor doing what it should do to protect itself when you hit the starter before the glow plugs finished their cycle.

rScotty

 

[Gregster613]

Cal, there is no mystery there. If you add up the amps for the glow plugs and starter it makes perfect sense that it would easily blow a 30 amp fuse. It would only be a problem if it didn't do that.

So no foul and no harm done. It's just your tractor doing what it should do to protect itself when you hit the starter before the glow plugs finished their cycle.

rScotty

Scotty, Not to disagree at all - but if his engine was running previously and was already warmed up - why would he have used his glow plugs again for a restart? I always use my glow plugs for a "pre-start" but never need them after I've been running. I think something else must have occurred. JMO

 

[thclimer]

Scotty, Not to disagree at all - but if his engine was running previously and was already warmed up - why would he have used his glow plugs again for a restart? I always use my glow plugs for a "pre-start" but never need them after I've been running. I think something else must have occurred. JMO

On my TC33D I don't have a choice to use or not use the glow plugs, they are built into the starting cycle. There is a timer which controls how long they are on. The first turn of the key activates this timer, the next turn engages the stater.

When the tractor is warm I have gone right to the start position while the glow plug light is still illuminated without a fuse blowing. I believe this is also the situation on my 1736.

Could a low voltage battery contributed to the fuse failing?

 

[rScotty]

Scotty, Not to disagree at all - but if his engine was running previously and was already warmed up - why would he have used his glow plugs again for a restart? I always use my glow plugs for a "pre-start" but never need them after I've been running. I think something else must have occurred. JMO

You might be right, I'm just judging from my own diesel equipment combined with a mechanical repair tendency to always go for the simplest explanation first.

The older diesels used to have the manual switch option of turning on the glow plugs or not - and of course that could blow a fuse if the starter was used at the same time.

My newer diesels are more automatic, but the same demand for too much current can happen by ignoring the dash warning to wait, and simply rushing the starting.
And that is exactly what the OP said he did...he did say he had rushed the starting:

"I usually wait until the glow light times out to activate the starter. But in this incident, I reached for the key only moments after the engine bogged."

That would cause the fuse to blow. As you say, it might not be the reason.
But right now I think it fits the "simplest explanation".

rScotty

 

[CalG]

Thanks for all the great considerations.

Just a note: After putting in the new fuse, and before reassembly of the cowl and steering wheel. I wanted to test to see if the fuse would blow again right away, Turned the key without waiting on the heaters, engine (Mitsu S4L) started right up!
The heaters are on an automated timer that is supposed to take into account engine temp.

 

[rScotty]

Thanks for all the great considerations.

Just a note: After putting in the new fuse, and before reassembly of the cowl and steering wheel. I wanted to test to see if the fuse would blow again right away, Turned the key without waiting on the heaters, engine (Mitsu S4L) started right up!
The heaters are on an automated timer that is supposed to take into account engine temp.

That's how I understand it too. But the software (or relay) that should prevent both circuits from drawing power at once is only as good as the designer's ability to cover all the possibilities. With so much eletronic control becoming popular in the last 30 years, covering all the possibilities can be difficult.

When the OP suddenly stalled it in 3rd gear, he may have gottne bitten by one of those unforseen coincidences in the circuit logic.

The big step in diagnosing a mechanical problem is finding a way to get it to repeat. Once we do that, how to fix it is usually obvious. I'm betting that is what will happen here, and wouldn't do anything until the OP figures out how to make the problem repeat.

rScotty

 

[Fladogman]

Sounds like a loose wire shorting out during vibration by heavy work and frame flexing

 

[CalG]

Sounds like a loose wire shorting out during vibration by heavy work and frame flexing

That is my thinking also. It is crowded with wires and connectors under the steering nacelle. Rodents are real ;-) I looked, but wanted to finish up with digging out that stump. If it repeats, hopefully I'll get it back to the shop for a good look.