I would like to share some experience with the Yanmar 1GM10 diesel engine. Since I’ve been sailing a Westsail 32 engineless for over four years now, coming into a boat like the FC (#27) with a Yanmar 1GM10 opened up the shallow bays along the Gulf of Mexico I could never reach in the previous boat. Mind you, I know nothing about diesel engines!
Our first real use of the engine was in 4 foot following waves and 20 kt winds for 10 nm. The tank was 1/2 full (28 gallon Costa Mesa CA SS below engine). RPM 2800 maximum, with occasional drop to 2000.
I topped the tank off with new fuel - adding about 15 gallons.
The next real use was in similar conditions, with similar performance.
The next outing we completed a 35 nm sail in calm to moderate conditions and started the engine for lack of wind. RPM 2600 for perhaps 3 nm. Stalled. It woudl restart after sitting for 10 minutes but stall again after 15 minutes. RPM 900.
I changed a fouled fuel filter and it now runs like before, RPM 2800.
I changed the oil, using T6 synthetic. I added StarTron fuel treatment.
A few outings, RPM 2600 under load but no stalling.
I bought a laser tachometer, measuring the RPM against the tachometer. The tachometer reads low. RPM 3700 no load. Tachometer reads 3500. RPM 2600 under load. 6" propeller and prop shaft turns freely by hand.
I thought this was as good as it was going to get and I was pleased anyway and enjoying the little engine.
Next, wanting to calculate cruising range with 28 gallons, and wanting to burn out all the old fuel, tied her to the dock and ran the engine full throttle under load. She ran for 50 hours straight. > 300 nm @ 5kts estimated range full tank.
I put a wooden rod into the filler port and found an oily brown residue with 1/4" fuel. I checked the fuel filter - spotless and like new.
I put in 5 gallons new diesel, added Startron.
Engine starts instantly, and now by hand using the crank and decompression lever, and without batteries.
RPM under cruising load 3200 (not tied to a dock) with less than 5 gallons fuel after 20 nm sail in 5 to 30kt wind 2 foot seas. Still starts by hand and intantly. Fuel filter remains clean.
I’ve had opportunities to visit with several diesel experts. The comment that sticks was “Sounds like you cleaned out your injector with the 50 hour run and Startron.” I am of the mind if there is no water/fuel interface for organic growth, there will be no growth at all, so I am hoping the sludge will eventually burn out. This option is much better than a new fuel tank, tank washing or fuel polishing in my opinion.