Ask Sail: Soot or Something Else? - Sail Magazine

Ask Sail: Soot or Something Else?

There is a soot-like buildup on the face of the alternator on my diesel engine. I have not noticed any fumes or exhaust leakage in the engine compartment.
Author:
Publish date:

SOOT, OR SOMETHING ELSE?

There is a soot-like buildup on the face of the alternator on my diesel engine. I have not noticed any fumes or exhaust leakage in the engine compartment. What are your thoughts or comments on what it might be?
Mike Asbury, Dandridge, TN

Nigel Calder is an author and expert on boat systems and diesel engines

Nigel Calder is an author and expert on boat systems and diesel engines

Nigel Calder Replies

This is most likely very fine belt dust from accelerated belt wear. There are three likely causes: the belt is a little loose and is slipping under load (mostly right after the engine starts when the alternator goes to full power); the pulleys are worn so the belt is bottoming out in the pulley grooves (belt loads should be transmitted through the sides of a belt, not through its base); or the pulleys are misaligned. If your pulleys are rusty, this will also accelerate wear. The most likely cause is that the belt is a little loose and is slipping when the alternator is at high levels of output. This will cause the belt to get hot and become hard and “glazed” over time. If you look closely you will see hairline cracks running from the center of the belt toward its perimeter. Quite often, a slipping belt will also squeal, sometimes just momentarily after the engine is cranked. When checking belt tension you should not be able to depress the longest stretch of belt more than 3/8 to 1/2in with quite a bit of finger pressure.

Related

Sunset-Tyrrel-Bay

Charter: Glorious Grenada

In the wake of the hurricanes that devastated the Virgin Islands last year many charterers ended up going farther south to Grenada and the Grenadines where they found the sailing excellent and the vibe just fine“God must have been a sailor when he created the Caribbean,” a friend ...read more

WaterLinesNov

Waterlines: Tangled Up in Pots

I learned to sail on the Maine coast as a boy, and one of the things my elders taught me was to respect fishing gear. If you got caught up with a lobster pot, you did everything you could to get clear without cutting the pot warp. It represented a family’s livelihood and thus was ...read more

7353

Harken’s Reflex 3 top-down Furler

Furl PowerAre you afraid of flying—spinnakers, that is? Harken’s new Reflex 3 top-down furler will tame A-sails on monohulls from 44-58ft and multis from 39-55ft, and Code 0’s on 39-54ft monos and 36-50ft multis. All you do is heave on the furling line and the sail will roll up ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell.Got a tip? Send it to sailmail@sailmagazine.comDitch the stress Owners of high-freeboard yachts best boarded via the stern sugar-scoop like to back them into a slip, but the process can be fraught on a windy day or when there’s a current running, ...read more

Sun-Odyssey-490-Bertrand_DUQUENNE-aft

Boat Review: Jeanneau Sun Odyssey 490

True innovation in monohull sailboat design can be a bit elusive these days. That’s not to say that there are no more new ideas, but it does seem that many new tweaks and introductions are a bit incremental: let’s say evolutionary rather than revolutionary. Just when it seems ...read more