Quote:
Originally Posted by Gladrags1
I think I may have a small fuel leak. When manually pumping the bilge, I get a bit of a sheen of diesel fuel. Granted that it could be from a previous owner's spill as a tablespoon of diesel will create a large rainbow but I would like to make sure that my aluminum tank that sits in the bilge is not leaking. I understand that a method of testing for leaks is to pump 3 psi into the tank and let sit for about 4 hours to see if there is any loss of pressure. I would like some advice upon the best tools to buy for this job. Or should I turn this job over to my diesel mechanic? Which will cost more - the tool or the mechanic? I have a shop air compressor. What else is needed?
Tod
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Tod - what are the dimensions of your tank?
What are the materials of the tank?
Pressure hold testing: A few psi hand pumped into an empty tank, monitored by a large scale semi-accurate gauge, etc. should be fine to ascertain a leak-down or 'pressure hold' test for pin holes, etc. You will of course need to totally block (cap) the fill port and vent and check all the 'capped nozzles' with soapy water. Such pressure hold testing is NOT the realm of diesel mechanics .... and will cost you diesel mechanic prices for something that they do not ordinarily do ... .
Most metal boat tanks will develop pin hole leaks in the bottom (sump) along welds and sharp bends of the sheet metal. These areas are usually impossible to visualize - unless you have a 'bore-scope' that can fit through the limberholes under the tank.
An easier solution is to lay-down paper towels at the exit of the limberholes under the tank, and simply occasionally check for the paper to 'take-up'/absorb any emitting diesel oil .... much less hassle than doing a pressure hold test.
The good news for any metal tank is that you can (cut) open the tank, apply epoxy/cloth to suspect areas; then, 'reline' the tank with a 'lining' epoxy to seal any pin holes, etc. .... so you dont need to 'replace' a leaky metal tank. Lining epoxies are specially formulated to be rolled-on. A good source for small quantities of 'lining epoxies' is:
Progressive Epoxy Polymers and Resins - Home Page Pittsfield, NH (a 'crappy' website but good products, including epoxies for lining potable water tanks, etc.)