I think you might be right Nigel with the external fouling. Something that crossed my mind. The boat was moored in Hiroshima, Japan at a marina where it seems the growth is excessive ( there’s a huge oyster industry here). Next time I go to Japan, I’ll dive and clean the bottom, especially along the keel cooler pipe. Many thanks. Steve

We went out again today and didn’t get the sulphur smell this time. I don’t know what that was. AGM due to the 14.5V alternator? It was intermittent.
Anyway, were were running engine tests that I think I got from this course, and we got white smoke out of both engines when at 2850rpm, one of the engine coolant temps rose to 204degF, but the exhaust elbow overtemp did not alarm. This engine has the water heater in the circuit. and has 590h. the other engine has 2871h.
I didn’t check cylinder head temps until we throttled back to 1200rom, but they were all about equal in the areas next to each injector.
These are Volvo D2-40s

Daniel,

Yes, plug in the shorepower cord to the dockside pedestal and the boat. As noted, this test is for simple shorepower-only AC circuits (no isolation transformer, inverter or generator). It requires the circuit to be powered up because otherwise there will be a 2-pole circuit breaker which breaks the neutral connection. And because the circuit is powered up, as also noted in the text, you must check with a voltmeter to ensure you have the neutral and grounding terminals when testing before switching to the ohms mode.

When plugged in you should have a low resistance between the neutral and ground (likely ~1 ohm, but it may vary a little), and then when unplugged this should go to a very high resistance/OL, which tells us the neutral to ground connection was on the dock. If there is still a low resistance connection, it is on the boat and needs to be tracked down and broken.

It gets a bit more complicated with onboard power sources. Depending on your inverter and how the generator is wired, you almost certainly either have a shore/generator selector switch, or the shorepower and generator are wired to an input on the inverter (e.g., a Victron Quattro), or maybe a combination of these. You may or may not have an isolation transformer on the shorepower inlet. So, potentially quite a few different possible combinations.

In the absence of an isolation transformer, if the boat is properly wired, when you are not plugged into shorepower, the generator is isolated, and the inverter is turned off, you should see no neutral to ground connection. When the generator is brought online, you should see the neutral to ground connection. The same for the inverter.

If you have an isolation transformer, regardless of the power source (shorepower via the transformer, inverter, or generator) you should see a low resistance connection neutral to ground connection. In this case it is not so easy to see if you have more than one and it gets a bit more involved than I can cover here.

Nigel

Daniel,

You understand it correctly! Thanks for the additional clarification!!

Nigel

Steve,

Do you think your keel cooler could be externally fouled with marine growth, restricting its heat transfer properties at higher engine loads?

Because of the coincidence with changing the antifreeze, I would drain a sample and check for deposits. If present, you likely have internal fouling.

Other possibilities include engine overloading, but it would have to be significant to kick in at 2100 rpm, and pump wear or thermostats not fully opening, but the latter two are uncommon.

Nigel

Rich,

Not sure what to suggest! Need more clues!!

Nigel

Rich,

You could look at a Sterling alternator-to-battery charger. Much more expensive than a diode but a lot more sophisticated!

Put the A2B between the alternator and the AGM batteries and keep the XS12/12 between the AGMs and the li-ion.

Nigel

Am I correct in understanding that in this case we MUST disconnect any other connection between AC ground and the grounding bus (hopefully there is just one)? Regardless of whether I am on shore or generator power, with or without the inverter providing its own or synchronized additional power, the case ground on the inverter/charger will remain as my mandated single AC ground to grounding bus connection?

Is there a way to drop the alternator voltage to the AGM? A diode? At least that drops it to 13.9V.
The Victron DC converter is programmed for the house bank, and it would also see this reduced alternator voltage.