Today's Engine Oddity (Universal 5432)

[Christian Williams]

I mashed the glow plug button in preparation to start and the ignition turned off.

Shore power was off. I plugged it in and the engine started normally. Unplugged again. (No idea if actions are related.)

After the ignition turned itself off a few more times when glow plugs were engaged by their separate solenoid, the starter motor burped once.

Next try, the engine started normally. After warming up, it started numerous times without incident. The cockpit panel wiring is in good shape, all grounds firm. The batteries are at 100 percent. This has never happened before.

Why would the glow plug button turn the ignition off at the panel?

 

[Pete the Cat]

I mashed the glow plug button in preparation to start and the ignition turned off.

Shore power was off. I plugged it in and the engine started normally. Unplugged again. (No idea if actions are related.)

After the ignition turned itself off a few more times when glow plugs were engaged by their separate solenoid, the starter motor burped once.

Next try, the engine started normally. After warming up, it started numerous times without incident. The cockpit panel wiring is in good shape, all grounds firm. The batteries are at 100 percent. This has never happened before.

Why would the glow plug button turn the ignition off at the panel?

I would look at the grounds again. I would follow Nigel Calder's excellent checklist for non start. Check the voltage drop on the main ground to the block and work backwards on grounds to the shared ground of glow and ignition. Grounds can look just fine to the naked eye and still not be conducting adequately. Follow the grounds. If the batteries are 100% (as measured by what?? )voltage is not a reliable measure as I am sure you know. Even battery monitors that measure amps in and out cannot keep track of actual storage capacity--you can only confirm this with amp test instrument. But I would strongly suspect a ground in the system that is not fully grounding. Could also be the mess of positives on the starter solenoid which is a positive trouble point. These get stacked and corrode in between them. I assume you have gotten rid of the trailer hitch connection for the engine wiring. This is something everyone should do ASAP on any Kubota installation. Let us know how it comes out.

 

[Kenneth K]

I mashed the glow plug button in preparation to start and the ignition turned off.

Not sure what you mean by "ignition," as there is really no ignition system on a diesel. What specifically was "turning itself off" when you energized the glow plugs?

 

[G Kiba]

I believe he means the key (ignition). Just a thought. Maybe the key did not turn off and the low oil pressure buzzer quit for a short moment (possible ground issue there). The lack of buzzer sounded like the ignition was off.

 

[Christian Williams]

The cockpit panel is energized by a push-pull switch. Buzzer sounds, gauges come alive.

Pushing the glow plug button shut the cockpit panel off.

Felt like a short, happened several times, however after that the engine started normally and I couldn't reproduce the issue.

 

[Kenneth K]

It does sound like a short. Are the glow plugs and starter motor on the same or separate circuits? I could see how engaging the starter motor (but maybe with not quite enough juice to get it turning) might replicate a non-repeatable short. Can't see how that happens with just the glow plug relay though.

 

[Christian Williams]

Ran fine last few days. Can't find a short or reproduce the problem. That is, as everybody knows, worse than having a real problem.

 

[Pete the Cat]

Ran fine last few days. Can't find a short or reproduce the problem. That is, as everybody knows, worse than having a real problem.

This is where my OCD kicks in.

 

[Kevin]

Kind of a long shot, but I have had one of those sierra ignition/key/on switches fail after only a year. In my case it actually stayed on when switched off, I suspect some salt water got in there. Perhaps if it happens again you can try a new switch. Worst case scenario you at least have a spare.