My boat has a marinized Kubota diesel hooked up to a new 12 V cranking battery. Until recently, this battery was starting this engine without issue. Now, when I turn the ignition key to the start position a single “tick” sound can be heard as everything hooked up to the cranking battery through the isolator switch goes dark. After this happens, the voltage reading of the battery is ~12.6 V while the voltage reading at any point after the isolator switch is ~5 V. As an example, I have a USB socket with a voltmeter on it which is wired to the distribution panel, and a handheld multimeter connected directly to the battery. The multimeter will show 12.6 while the voltmeter will initially display around 5 V. Over time the voltage after the isolator switch will slowly creep back up to match the voltage of the battery. This takes more than 15 minutes. Once it gets there, everything connected to the battery through the switch is once again powered and the process can be repeated. I have a limited understanding of electricity and find this very puzzling.
The issue first appeared when I attempted to restart the engine after it cut out when I idled the throttle too quickly. This was after motoring for more than 2 hours. The first time I attempted restarting, it sounded like the starter *very* briefly tried to turn the engine. Like it turned a tiny fraction of a full turn before the power abruptly cut. That one time the sound was more of a metallic thud or a clang. I don’t think the “tick” I’m hearing now is the solenoid, but I’m not absolutely certain. To me, it sounds like an arc pop, which makes me think there is a short somewhere.
Things that I’ve tried:
* Removing the solenoid and powering the starter motor directly from the battery using jumper cables. It works and turns the engine over just fine when I the pinion gear is manually engaged.
* Replacing the solenoid with a brand new one. Same issue persisted.
* Tested the voltage at the B and S terminals of the solenoid. Both showed 12.6 V.
I suspect something is wrong with the starter, but I’m not sure because the starter seems to work fine when connected directly to the battery, i.e., a lead going from the battery's + terminal to the motor strap on the starter, and a lead going from the engine block to the battery's - terminal.
All advice, ideas, suggestions, warnings welcome.
The issue first appeared when I attempted to restart the engine after it cut out when I idled the throttle too quickly. This was after motoring for more than 2 hours. The first time I attempted restarting, it sounded like the starter *very* briefly tried to turn the engine. Like it turned a tiny fraction of a full turn before the power abruptly cut. That one time the sound was more of a metallic thud or a clang. I don’t think the “tick” I’m hearing now is the solenoid, but I’m not absolutely certain. To me, it sounds like an arc pop, which makes me think there is a short somewhere.
Things that I’ve tried:
* Removing the solenoid and powering the starter motor directly from the battery using jumper cables. It works and turns the engine over just fine when I the pinion gear is manually engaged.
* Replacing the solenoid with a brand new one. Same issue persisted.
* Tested the voltage at the B and S terminals of the solenoid. Both showed 12.6 V.
I suspect something is wrong with the starter, but I’m not sure because the starter seems to work fine when connected directly to the battery, i.e., a lead going from the battery's + terminal to the motor strap on the starter, and a lead going from the engine block to the battery's - terminal.
All advice, ideas, suggestions, warnings welcome.
