The throttle is the standard Hynautic brand hydraulic control system which uses diluted anti-freeze for fluid. The fluid is pressured to about 80 lbs in the system. Any foreign matter, such as metal shavings, will not mix with the fluid and clogs the jets in the control box, jamming the lever. In our case at lowest throttle. Attempts to bleed off some fluid in hopes of un-jamming the system were futile.
This morning, Thursday, Alex pulled the traps with the tender and harvested a dozen large prawns, quite happy the commercial prawn season hasn't yet opened. We decided to repair the throttle at our next stop Shearwater, which has a boatyard. It would be slow going at 4 knots, so we jury rigged an engine room "string" throttle. Pat and Alex each donned the Toys R Us headphone walkie-talkies. When Pat at the wheel barked "cruising speed please", Alex in the engine room pulled the string. The throttled was advanced until Pat yelled "1300 RPM". Alex tied a knot and the Wild Blue was up to its 8.5 knot cruising speed. Of course to slow, someone needed to untie the knot on the string throttle.
We were happily motoring west in Lama Passage when one of those awful siren sounds started. The screaming source was clear: the engine panel siren. The manifold temp was at 170F, too high. We watched as the temp dropped below 170F and the siren stopped. This happened three more times and then the manifold temp settled at 167F. Obviously this engine issue needed to be addressed before continuing on to Ketchikan.
|Manifold temperature is 167F just 3 degrees below the siren sound.|
The overheated engine manifold was different. For the Cummins QSL9 engine, the absolute best mechanical mind on the Pacific Coast is Tony Athens of SB Marine in Oxnard, California. He's outspoken about all things Cummins, both good and bad, and serves as the Cummins engine moderator on the boatdiesel.com forum. He is the go to guy, and so Alex did, after reviewing all the relevant technical articles and how-to videos on http://www.sbmar.com. On the phone Tony was blunt: if the strainer is clean, the raw water impeller good, then an overheated manifold can only mean one thing: your aftercooler is full of "green guacamole". "You slow RPM trawler guys get more green guacamole in your aftercoolers than all other mariners! The air can't get cooled before it enters the engine because the aftercooler core is clogged. You have once choice: clean the aftercooler. Read my article. It's easy!"
We stayed a 2nd day in Shearwater and on Friday enlisted Loren's help again. Alex had the after cooler off the engine and on the dock. It took the boatyard's mechanical press to push out the core. And yes it was full of green guacamole as one can see from the photos. Per Tony's detailed website instructions, Alex was able to clean the aftercooler core by boiling it in a Simple Green solution. By the end of the day Friday we reassembled the aftercooler and re-installed on the main engine.
|Aftercooler core covered in "green guacamole". This sludge is created when the engine is run continuously at medium and slow RPM, the speeds at which trawlers run.|
|Boiling the core clean in a Simple Green solution. Nobody asked if we also had some crabs in there too!|