Cat 3126b smoke, grid heaters, and more lessons learned

[Mariner]

I figured I'd share my experience here in the hopes that it would help other owners.

I've been fighting an issue of worsening smoke coming from the engine exhaust for several years now. Compounding the problem has been the general lack of availability of certified Cat-certified marine mechanics with access to the Cat proprietary diagnostic system. Don't get me started on that....still haven't found one who will actually come out. But I did find a FORMER Cat certified marine mechanic WITHOUT access to the Cat propriety diagnostic system. Consequently, he was not able to evaluate the injectors, but he did tear apart the aftercooler and clean it up, which is a common problem on these engines. Unfortunately, the excessive smoke on startup persisted. He came back and suggested that we might have failed intake air heater (aka "grid heater") and that I should test it (But he didn't have time). So, I got down there with a multimeter and IR thermometer to see what was going on. Sure enough, it wasn't coming on. Common cause is a bad solenoid (the heaters themselves are very robust and almost never fail), but I wasn't even getting voltage TO the solenoid. I spent a lot of time trying to track that down until I finally figured out there is a little (blue, in my case) push-button circuit breaker mounted beneath the aftercooler, which had been tripped. I reset it and all of a sudden I had voltage at the solenoid, and what's better, there was voltage at the heater post itself, so the the solenoid was working properly. However, there wasn't MUCH voltage. I noticed, in fact, that it was quite low at just 12 volts flat, while the engine was warming up. Normally, I'd expect to see quite a bit more, as the alternator is charging the batteries at that point. But this heater appeared to be cycling on and off, and when it was on, it was really beating up the battery. So, I put a clamp ammeter on it, and it turns out that thing draws 80 amps. I did a little digging and discovered that my alternator is only 50 amps. So, for the first 13 minutes of running, the heater is drawing all available power from the alternator, and pulling the rest from the battery. I did a little research and found out that this is actually completely normal. I've been considering replacing the alternator with a higher-output one, but as the smoke at idle seems to have largely gone away, meaning I can comfortably idle in the slip to warm it up, I haven't done anything yet.

There's not really a question I have to ask other than perhaps to know if anyone has experienced this, or has upgraded their alternator. Mainly I just wanted to share. The takeaway for me was that I have purchased a set of Xantrex LinkLite battery monitors, which will allow me to monitor the overall charge state of the batteries, as well as monitor the amperage flow in and out of each, to give me a better understanding of where I'm at, so I'm less likely to find myself stranded with a dead battery, or one low enough not to be able to maintain that grid heater while the engine warms up.