Testing the diesel tank

14 May

Yesterday was more puttering around working on a handful of projects. I started out with the diesel tanks that I pulled out a while ago. They’ve been sitting around the shop and I’ve been fervently hoping that they don’t have any holes in them. To find out I put together a little pressure testing rig out of a couple pipe fittings and a bike pump:

That’s plugs in two of the holes and the third is just a threaded fitting with a bike tube clamped to it, like so:

Tying off the other end of the tube makes the whole system airtight, at least enough to get a couple pounds of pressure in there. Then I rubbed everything down with soapy water and looked for bubbles.

Unfortunately, there were plenty of them!
A vigorous cleaning revealed serious pitting and this 1cm hole:
I’m not sure what I’m going to do about this one. I haven’t tested the second tank yet but I expect it will be in the same shape. I really don’t want to replace the tanks as they fit perfectly and would be expensive to have remade but a leak in a diesel tank is serious business. If I do a poor repair job I might end up pumping leaked diesel over the side with the bilge water, which would be a disaster. So this is one repair that needs to be done right. I have a friend who welds aluminum and is confident that she could plug the holes but we’re worried about the potential for explosion as even very carefully cleaned tanks can have dangerous residual fumes. Plus it’s quite likely that more holes will appear before too long if it’s already this corroded. Another idea I’ve been tossing around is coating the tanks in thickened epoxy and then laying up fiberglass around them, in effect making a tank inside a tank. I think this might be the best option but I need to do a bit more research. If anyone has successfully done this before, I would love to hear from you!

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder


Leave a Reply

Your email address will not be published. Required fields are marked*. Comments are moderated and generally will be posted if they are on-topic and not abusive. For more information, please see our Comments Policy.

More from the AIM Marine Group