Hello I’m trying to troubleshoot shoot a problem on my 1999 416C Cat backhoe. When it is cold (winter in Canada cold) I can plug it in overnight and it’ll fire right up in the morning like it always has but once it warms up and I’ve been running it for a while if I shut it off and try to start it up it won’t start. It will crank over but it sounds like the battery’s are week when I try. The battery’s are only a year old tho and I’ve taken them off and load tested them and they are good. They were both at 13 volts when I took them off as well so seems like they are charging properly too. If I hook a charger/booster to it it will start up but still struggles. I’m guessing it’s the starter but it’s only 2 years old and the machine doesn't get that much use anymore so this starter doesn’t have many starts on it. Seems odd to me that the starter would be fine when it’s cold but be failing warm. Any ideas how I would test the starter? I’m not excited about getting another one to try. Or any ideas on what else it could be or what I should check? Thanks in advance
It sounds like a cranking issue rather than a fuel issue. What condition are the cables in and are all connections and grounds clean and tight? Could there be corrosion inside the insulation on the cables? Is the 13 volts with the engine running? If so that's too low. Needs to be 13.6 volts min. and preferably a little over 14 volts. I've never heard of a bare battery having more than 12.8 volts. Have you done a voltage test while cranking at the batteries and at the starter? If I had to guess I'd suspect the alternator or voltage regulator not putting out enough volts/amps especially if you're running the heater, lights, a radio etc. With accessories on the batteries are barely keeping up and actually draining a little bit.
How warm is it when you shut it off? Any hydraulic valves possible not closing on center. When it’s trying to start is it just turning over slow like cold or maybe a drag on hydraulics.
I would measure the voltage across the battery terminals when cranking. If under 10 volts your batteries are the issue. New does not equal good. It just means they are new. Always test. If not, measure the voltage drop on the positive and the ground. If you don't know how to do this read this Document. If you are of the I rather watch than read generation I am sure you can Google a video. Three measurements will get you a diagnosis.