Yanmar 3GM30Fe low power when cold

[phantomracer]

Originally Posted by skipperpete

I was actually the guy NOT advising injector removal, the Mackboring students suggested that and I only responded with thermostat advice because of your suggestion that” smoke is because a malfunctioning thermostat is cooling the intake manifold”. I have no doubt that a failed thermostat WILL cause smoke but it’ll be the paint on the engine smoking from the overheat. I still maintain that the OP’s smoke and loss of power is due to a combination of the Balmar reg setting and a lightly fouled propeller, I might be wrong and I often am…..I hope he lets us know how and if he fixes the problem

catching up on this topic...

when the boat was pulled, the prop had 'hairy' growth on it and some slime, very minor hard fouling. prop has pettit zinc paint on it, prop is a maxprop. (see attachment)

Bottom looked great, other than some slime. Picture shows boat as soon as it came out of the water. Looks pretty good for 2 seasons on West Marine CPP paint!

When the dark smoke comes, it smells of unburned diesel, and only comes for a moment when throttle is pushed further than the boat wants to go. the smoke does not last 10-15 minutes. maybe 1-5 seconds max and only when throttle is pushed hard. idle and low throttle, no smoke.

Happened whether the outside temp was hot or cold. engine starts flawlessly. always.

Best way to describe it is it feels like I am dragging a heavy weight behind the boat. 10-15 minutes later, it is fine.

engine has never over heated. Once warmed up, runs flawlessly.

I think the strongest contender is the regulator offering a lot of resistance, and likely the moderate growth on the prop. perhaps the prop was 'backwards', and not giving the best thrust..

Will probably hold off on doing anything on the injectors.

Will adjust the belt settings on the regulator, and try that out for a season.

[skipperpete]

Thanks for the update and photo Phantomracer. The prop is a bit over the “lightly fouled” condition
happy motoring!!

[DirtPete]

Very much appreciate the photo, agree with skipperpete.

[phantomracer]

yea, never seen hairy growth before. Usually it is just slimy and a couple pieces of hard growth (comes off easily). The hair came off easily too, but I am sure it did not help the situation!

[AA3JY]

Originally Posted by phantomracer

catching up on this topic...

when the boat was pulled, the prop had 'hairy' growth on it and some slime, very minor hard fouling. prop has pettit zinc paint on it, prop is a maxprop. (see attachment)

Bottom looked great, other than some slime. Picture shows boat as soon as it came out of the water. Looks pretty good for 2 seasons on West Marine CPP paint!

When the dark smoke comes, it smells of unburned diesel, and only comes for a moment when throttle is pushed further than the boat wants to go. the smoke does not last 10-15 minutes. maybe 1-5 seconds max and only when throttle is pushed hard. idle and low throttle, no smoke.

Happened whether the outside temp was hot or cold. engine starts flawlessly. always.

Best way to describe it is it feels like I am dragging a heavy weight behind the boat. 10-15 minutes later, it is fine.

engine has never over heated. Once warmed up, runs flawlessly.

I think the strongest contender is the regulator offering a lot of resistance, and likely the moderate growth on the prop. perhaps the prop was 'backwards', and not giving the best thrust..

Will probably hold off on doing anything on the injectors.

Will adjust the belt settings on the regulator, and try that out for a season.

Is that a Max Prop?

[phantomracer]

Originally Posted by AA3JY

Is that a Max Prop?

yes, it is a maxprop

[bil56]

seriously, with a propeller in such a state, are you surprised to have an engine that smokes black?

./.

[AA3JY]

Originally Posted by phantomracer

yes, it is a maxprop

New info that wasn’t in the original post

[skipperpete]

Originally Posted by phantomracer

yes, it is a maxprop

Hey Phantomracer, you might not need to change the regulator setting , judging by the way you describe the smoke clearing, the propeller and alternator relationship sounds about right if the maxprop is clean.

[phantomracer]

Originally Posted by bil56

seriously, with a propeller in such a state, are you surprised to have an engine that smokes black?

./.

I didn't know until the boat came out of the water. Also this is the first time in 15 years I ever saw that kind of string/fur fouling. Usually it is just slime at worst

[phantomracer]

Originally Posted by skipperpete

Hey Phantomracer, you might not need to change the regulator setting , judging by the way you describe the smoke clearing, the propeller and alternator relationship sounds about right if the maxprop is clean.

could be. First time this kind of fouling has ever happened. Usually it is pretty clear other than slime.

I reaaaaly feel the alternator when it is in bulk mode! when it is in float, feels a lot more powerful!

attachment is usually what it looks like fresh out of the water after a season