Hard-to-Find Mercedes Parts – Knotmeter Fouling

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Hard-to-Find Mercedes Parts

I have a 190 DC diesel auxiliary. I desperately need to find a good exhaust manifold for it. It has a heat exchanger, and I have marinized an old manifold, but surely there must be someone who has a better way.

Given the number of Mercedes diesels you see on the highway, its amazingly difficult to find parts for the marinized versions of these engines.

Part of the difficulty is the origin of the marine versions of the various Mercedes engines. Mercedes, like several other engine manufacturers, doesn’t make marine diesels. They do, however, license other companies to do marine conversions using their engine blocks.

The company currently marinizing Mercedes marine diesels is Nannidiesel Corporation www.nannidiesel.com.

Since there are two very different Mercedes diesel engine designs – one a pushrod engine, the other an overhead cam engine – you must know which type you have before ordering parts.

Yanmar Diesel Clinic

My new boat has a Yanmar diesel. Although the instruction manual is pretty good, this is my first diesel engine, and Id like to do a good job of taking care of it. Does anyone offer courses in basic engine care that would be helpful to the average all-thumbs boatowner?

Mack Boring www.mackboring.com has courses for owners of Perkins and Yanmar diesels. These courses are specifically designed for the inexperienced diesel owner, and cover the basics of maintenance and operation.

There is no charge for the course, although there is a registration fee required, which is returned to you when you show up. The course is usually booked months in advance, so don’t expect to just walk in the door.

Hard-to-Find Mercedes Parts – Knotmeter Fouling

Mack Boring is a major distributor of marine diesels.

We arent aware of any other manufacturers or distributors who offer similar courses, although there is a real need, since diesel engines have slightly different needs than the gasoline engines most car and boat owners are familiar with.

Knotmeter Fouling

My boat is moored in a tidal river with a constant current of one to three knots. Although I clean the knotmeter turbine thoroughly when the boat is launched, it is usually inoperative after about a week from grass growing on it. Is there a freer moving impeller I can use that will stay cleaner?

Is the problem really grass growing on the impeller, or is the impeller simply catching debris? We suspect that the problem is not growth, but the amount of junk carried by the river.

You may have other problems besides a fouling transducer, however. If the impeller turbine is constantly turning, you will greatly accelerate the wear on the turbine bearing, reducing the life of the transducer. With three knots of current running 24 hours a day, youre putting 500 miles a week on the impeller bearings without moving off the mooring.

If you have a removable impeller, you should take it out anytime the boat is left on the mooring for more than a few days. Youll not only keep the impeller turbine from fouling, youll increase the life of the unit.

If you don’t have a removable impeller, youre probably stuck. We don’t know of any other transducer that would particularly relieve the problem. If a knotmeter is important to you, it is probably worth springing for a new one that comes with a removable impeller and a dummy plug.

Incidentally, if you have a knotmeter with a removable impeller, its best to practice the procedure before you launch the boat, as the first time you pull the impeller out once the boat is in the water can be an unnerving experience if you don’t know exactly how to do it.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him by email at practicalsailor@belvoir.com.