Komatsu PC28uu starts intermitently

[MikeMilaca]

Hi all - looking for some help before I start tearing down the machine.

Machine sometimes will fire right up. It goes through the starting sequence - two beeps with all four indicator lights, then just the oil pressure and battery light, then turn it to start, and boom - start.

Sometimes (everything the same up until the turn) and it’s just makes a “dink” sound and does not start.

Few hours later or the next day, and suddenly decides to start. I’ve checked this with operator presence lever in the correct position, and making sure the bucket is not in an alarm position.

I don’t know if I have a bad safety switch that’s cutting off the power to the starter, bad relay, bad solenoid. It doesn’t seem to be the starter because it’s never made any bad noises, or try to turn over when this happens. I just get the “dink”.

Any help would be hugely appreciated!

Thanks - Mike

 

[John C.]

I can only guess about the noise you are hearing. Usually a click sound would be the battery disconnect closing. Komatsu excavators are usually set up so the oil pressure light doesn't come on unless the engine is running and there isn't enough pressure to close the switch. Your machine is likely a gray market unit with that UU in the model number. Does your machine have three wires doing to the back of the alternator?

 

[MikeMilaca]

Thanks for the response. It is gray market.

The light has always come on like that … long before this problem ever happened. I think it just lights as part of the startup sequence. I know the oil and hydraulic fluid are topped and good, and have never had it come on while running.

I’ll see if I can record a short video of the start-up sequence and sound.

I’ll check the wires to the alternator. It’s a bitch to get to though. I think I need to pull the radiator.

Hopefully I get some other ideas in the meantime.

 

[John C.]

Some machines have a panel in the wall just forward of the engine.