April 2002 — By Capt. Patrick Sciacca
Fuel Tank Failure
|Part 2: Your fuel tanks’ fate is not sealed.|
The situation may seem hopeless, but your fuel tanks’ fate is not sealed. There are ways to maintain, improve, and extend their quality of life. Before you head out to the deep blue this and every season, look for warning signs of fuel tank contamination, which may hint at the presence of corrosion. Appelt identifies several key factors, including sludgy fuel filters, the necessity of frequent filter changes, inability of engines to hit their full rated rpm, dark exhaust smoke, soot on the transom, water in fuel-water separators, and engine stoppage. A less-obvious sign of tank corrosion is hard deposits on diesel injectors. This is something that would most likely only be found by your engine technician during a spring tune-up, unless you do a lot of engine work yourself. Fuel in the bilge also can be, but is not always, an indicator that your tanks have been compromised.
If you suspect you have a leaking tank, you’ll want to have it pressure-tested. Since this requires that all vents, inlets, and outlets be covered, it’s best to leave the job to a professional. He’ll typically place a pressure gauge on the tank while applying about 3 psi of air pressure. If the tank maintains that pressure for six to eight hours, it passes muster. If not, it’s on to a tank survey, which entails a visual inspection by an expert to determine the degree of the external and internal corrosion.
Fortunately, tanks can be repaired if they’re corroded from the outside. (Appelt advises replacing a tank corroded from the inside.) Sometimes the job can be done in place, but this is not recommended. Aluminum tanks can be repaired by applying a patch. The damage is first cleaned by sandblasting or wire brushing, then a patch of heavy fiberglass cloth and epoxy resin is bonded to the tank. Appelt noted that monel tanks could be repaired in the same fashion. However, if the leak is on a weld, the whole area will have to be welded–no spot welding. Any suspicious spot left unattended will ensure another trip to the welder.
If your aluminum or monel tank appears to be a bit rusty on the inside but is otherwise in good condition, look for a company like Quality Yacht Service in your own area that specializes in draining and cleaning marine fuel tanks. Don’t try to do the work yourself, however. This is not a small maintenance job, so you’re better off having a reputable professional tackle the problem.
When it comes to repairing a fiberglass tank, unless you’re familiar with fiberglass repair and know how the tank was constructed (including what kind of coring may have been used), it’s best to leave the work to a specialist. Even the simple cleaning of a fiberglass tank presents challenges if the interior isn’t gelcoated, since debris will cling to a rough surface. Even with professional cleaning it may still stick to the tank sides.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.