Komatsu PC75uu-2 Starter Problem

[Smedlow]

1. My 1994 PC75UU-2, Serial number 8310, Engine Model # 4D95L-1, was getting harder to start. I replaced the batteries but still turned over slow. Had a friend try and start while I watched and fire/smoke came out of the rear of the starter motor. Now it won't turn over at all. I suspect the armature is dragging on the field coils. I need to remove the starter and don't have the service manual.

Do I have to take the counterweight off to access the starter, or can I remove enough linkage and manifold parts to get it out through the top?

2. Update: I hooked two batteries up in series and applied 24v. to the starter solenoid and then to the starter motor and then the solenoid after tapping on the starter housing. The solenoid engaged normally, but the starter motor contact arced a little but didn't move. After several tries, I guess I jolted something loose, because it started, turning over at normal speed. It remains to be seen whether it will start tomorrow, but there is clearly a problem. I was desperate to get it started because I wanted to get it somewhere I could work on it and put it in the right orientation.

3. Finally, the oil level is increasing. I can only imagine that somehow diesel is getting into the crankcase and mixing with the oil. Maybe the diaphragm in the fuel lift pump, as has been suggested elsewhere. So...where is the fuel lift pump?

4. I have a parts manual in Japanese and and operation and maintenance manual. Anyone have a service manual?

 

[Randy88]

I'd have to look again, but mine is a -3 but I think the engine is the same. As for the starter, its easier to remove if you take the counterweight off, and also a lot faster compared to doing it through the hole from the bottom of the engine compartment, you can have the counterweight off and starter changed and the counterweight back on faster than one or two people trying to do with the counterweight still on the machine.

If your having starter issues, take it off and have it rebuilt if possible, or else buy a new starter, check for voltage drop at the starter BEFORE you install a new starter and fry the contacts in the solenoid and need to remove it again. I'd put new cables and batteries in along with the starter if it were mine.

Its been a few years, but the lift pump being electric rings a bell, but once the counterweight is off, everything is clearly visible and most of your questions will answer themselves.

Just by chance does the engine have a slight miss at idle?? or smoke blue at start up??

That excavator should be 24 volt and if your trying to start it on 12volts you will have issues, major issues.

Send in an oil sample to see if your having a fuel dilution issue or exactly what is in the oil to increase volume in the crankcase, compared to guessing, the cost is cheap for the oil analysis. Best of luck

 

[Smedlow]

Thanks for your reply, Randy88. The darn thing is starting now since I hotwired the starter. I know that is likely a temporary condition, but I haven't had time to tear it down yet. I am sending in an oil sample for analysis. Great suggestions!

 

[Randy88]

I looked the other day the fuel pump is mechanical attached just below the injection pump. If it is fuel dilution, you have plenty of places it could be coming from, but the oil sample will tell you for sure if that is what it is causing an elevated oil level.