Diesel Engines

Salt and water conspire to reduce our boats, our pride and joys, to pitted and unreliable money pits. Weve investigated corrosion of wiring (see PS July 2010 online), gasoline (see PS August 2012 online), diesel (see PS August 2013 online), and winterizing fluids (see PS September 2014 online), uncovering additives and practices that dramatically reduce deterioration and increase reliability. Engine cooling systems have similar vulnerabilities, and fortunately for us, the automotive engine manufacturers have invested millions in finding those solutions. However, the marketing materials don't always make the differences clear, and its hard to know which product is the best for your engine.

Samples were tested for corrosion protection following the ASTM D1384 Corrosion in Glassware method (www.astm.org). Samples were diluted to 33-percent glycol, dosed with ASTM synthetic corrosive water (similar to 2-percent seawater), continuously aerated, and heated to 190 degrees for two weeks. As a laboratory control, a reference coolant (ASTM D 3585) was also exposed to provide a baseline.

Protecting marine water systems from freeze damage is a deceptively simple goal. The terminology and various product claims can be confusing, and what seems like a good common-sense decision can lead to trouble. We tend to think that all water systems are the same; that boats as well as RVs can be protected by the same pink antifreeze without any further thought. However, many of the problems we associate with age, or normal wear and tear-stiff impellers, cracked pipes, ruined joker valves, and foul-tasting tap water-can often be attributed to errors during winterization.

We tested each product for glycol content using a refractometer and either the ethylene glycol or propylene glycol scale, as appropriate. In the case of Camcos Arctic Ban and Sudburys Winter Stor, some portion of the freeze protection is provided by ethanol, and such mixtures cannot be easily evaluated by any field method (test tape, gravity, refractometer) unless the exact proportion is known, which we find troublesome.

Winterizing agents should never be used in freshwater tanks or hot-water tanks. Doing so will greatly increase the chances of biological growth, which can result in foul-smelling, bad-tasting water. If your boats water system does not have bypass fittings that allow you to add glycol to waterlines, install them. The addition of a few simple fittings can reduce the annual process from hours to minutes for the cost of a few jugs of glycol.

What matters most, our testing confirms, is not so much which brand of pink stuff you choose, but how you use it. Even the best product, mixed with too much water left in the line, results in a blend with unknown and perhaps unsatisfactory performance. While this may not be critical in North Carolina, sailors in Wisconsin need to get it right.

Through lab tests and years of field testing, weve found that silica-gel vent filters reduce tank corrosion and improve gasoline stability. But is the same true for diesel fuel and tanks? Thats what this test sought to find out. Testers put two silica-gel diesel tank vent filters through their paces: Pindell Engineerings AVD2 (for tanks up to 60 gallons) and AVD3 (for tanks up to 200 gallons). The results were compared to setups with a free vent and those with a sealed tank.

The Coast Guard and the American Boat and Yacht Council (ABYC) have worked together to develop general installation guidelines for the carbon canisters required under the EPA's evaporative emission regulations. While the standards (AYBC H-24) don't specifically apply to the H2Out AVD unit when installed in diesel fuel systems, they represent good basic commonsense and should be followed with any fuel tank vent adsorbent product. We have added a few tips and precautions learned during our testing.

Dont look to tank vent filters and fuel additives to solve real fuel-system problems. They are only ancillaries to regular fuel system-management and maintenance, improving reliability even further. Here are some fuel-system management best practices that we recommend.

The Environmental Protection Agency (EPA) and the American Yacht and Boat Council (AYBC) are requiring devices that prevent foam and splash during fueling and operation from reaching the carbon canister. If sea water did reach the fuel filter, it could destroy filter effectiveness and compromise venting capacity.