Damn, leaking fuel tank.

[Nauti Fox]

I suppose as they're nearly forty years old it had to happen at some time.
It was that horrible smell of diesel that made me have a look and sure enough, there it was. Unfortunately the leak isn't in this corner but somewhere under the tank which is mounted on a plinth and totally inaccessible.

The tanks are of course outboard of the engines.

While I figure out a way of solving this, and I do have a couple of ideas, as I really don't want to try and get the engine out (we live aboard). I need to route a return from the starboard engine to the port tank (which I had the pleasure of transferring 170 litres of diesel to yesterday) and luckily enough I already have a feed to both engines from the port tank.
So there we have it, nice list on at the moment, but might fill the starboard tank with water to level things out as the leak is very small and will take weeks (or months) to empty and I just hate the boat listing!

Next week I'll take off both return lines and get them made up to return to the port tank, I was going to do it yesterday but after four hours moving the fuel about I'm lucky I can walk!

The top of the tank

Which lurks behind here

 

[Tranona]

Feel for you having just spent many happy hours removing the leaking forward water tank of my boat. Rarely used it, and when I did it leaked halfway across the Med and deposited its conents through the gear stored in the locker behind it!. Failed weld that will cost next to nothing to repair.

 

[Trundlebug]

Your installation with its restricted access looks remarkably similar to mine. Except I have a sound proofing bulkhead between the engine and the fuel tank, making tank access even more difficult.

Although I have stainless tanks, there's no drain that I'm aware of and I really need to remove any sediment that must be lurking in there.

This winter I need to find out if there is a drain, and if not get access to the top of the tank where the fuel filler hose goes in through a 90 degree elbow, then poke a tube down to the bottom to suck out the grot.

With similar overhead clearance to you, i.e. inches, it's not a job I'm looking forward to. I've been putting it off for 4 years...

Good luck with your plan to get at it without removing the engine; I'm intrigued

 

[oldgit]

Any chance of grinding/cutting off one end/side/top and dropping slightly smaller tank "inside"
When one of my water tanks failed( yes it was outboard and under under side decks) hacked off the only accessable end and had a plastic one made up via firm on Ebay.
Although rigid plastic there was enough give to persaude it past several bits and pieces and locate itself inside body of old tank.

 

[Divemaster1]

I'll check with my friend who has a Laguna 11.5M .... Know that he had tank problems a while back ..... will ask him how he resolved the issue...

 

[Assassin]

I would suggest the following if you don't know where the leak is, obtain a product called "drain stain" which is a powdered stain for finding leaks in drains, and available in a range of colours. This is obtained from builders merchants and plumbing suppliers and simply mixed with water, it is biodegradeable and can simply be pumped overboard when you find the leak.

Clean the inside of the tank thoroughly and partially fill with water, pour in half the pot of drain stain and add more water and mix well, leave for a few hours/days as necessary, and see where on the tank or boat is stained. From this you can track back to the source of the leak on the tank by following the stained area.

Once you have located the leak you have two options for a cheap and permanent repair.

Option one is to obtain a product called "Plastic Padding Chemical Metal" which is a polyester based, but fuel resistant, repair paste very similar to car body filler. If you can reach the externally leaking portion of the tank you simply clean, abrade, and apply a couple of coats to build it up to 4mm thick, and it goes off very quickly, about 5-10 minutes at 20 degrees.

If the leak is on the bottom of the tank, and not accessible, i would advocate an epoxy resin based liquid repair system for fuel tanks. You simply clean the tank thoroughly, mix the two component parts pour them in the tank, let them fully harden for 24 hours and the repair is complete.

This saves considerable work in removing the tank unnecessarily.

Drain stain costs about £7 from reputable suppliers, and Chemical Metal is currently available from Cromwell Tools for just under £13 for a large tub; epoxy based systems vary in price and size.

It just may save you a lot of work and expense.

 

[Nauti Fox]

Thanks for the ideas, although I fear that as the tank is so old it would be prudent to get a bit more radical and that I would be forever chasing/worrying/looking for leaks and not enjoying "the boating experience".

 

[Elessar]

It was that horrible smell of diesel

smell remover enzime for tomcat spray from a pet shop needs to be on your shopping list.

neat on the very deisely bits, diluted around the whole area.

fix the leak first though!

 

[jfm]

If the leak is on the bottom of the tank, and not accessible, i would advocate an epoxy resin based liquid repair system for fuel tanks. You simply clean the tank thoroughly, mix the two component parts pour them in the tank, let them fully harden for 24 hours and the repair is complete.

That sounds a great idea to me Assassin. At least, it could defer the huge new-tank project a few years. I didn't know such projects were available

 

[Nauti Fox]

Forgot I had this photo, taken when I was changing the turbo.
There's actually more room than I thought, especially if the hinged hatch is removed (top right).

I'll have to check to see how easily the floor may come up outboard of the hatch, which will probably be difficult, floor is third from right from when I fitted the Eber.

 

[DAKA]

Thanks for the ideas, although I fear that as the tank is so old it would be prudent to get a bit more radical and that I would be forever chasing/worrying/looking for leaks and not enjoying "the boating experience".

I have replaced 4 tanks, alright 3 on the same 8loody boat and I would be very tempted to take advice on here and find the leak.

If its just a bolt head/screw that the tank has rubbed against then fixing the hole should be permanent.

Now on to the tale.............

Bayliner sports boat, aluminium tank 4 years old

leaked, repairable but I thought like you best to replace , the professional tank fabricator made a balls up and the new one leaked, and the second one until I got one flown in from USA as I lost faith in UK tank builders.

I would have saved 100 hours of balls ache if I had repaired the original tank.

My current boat had a holding tank seep, I was stupid enough to do the same again, took out a perfectly fitting tank that was easily repairable but chose to replace with plastic, horrid job as the new pipes/fittings just didnt want to re attach.

Best to find the leak and repair, even if you have to remove the tank it will save time as the old repaired tank with new base/side is sure to fit back where it came from along with the pipes/fittings.

Cleaning the area with bilge cleaner/detergent/water drying with a fan heater (diesel only) and then dusting with baby talc will also help trace the leak.

 

[Divemaster1]

Piece of cake

Forgot I had this photo, taken when I was changing the turbo.
There's actually more room than I thought, especially if the hinged hatch is removed (top right).

I'll have to check to see how easily the floor may come up outboard of the hatch, which will probably be difficult, ......

How wide is the tank ??

If floor is removed, could you cut tank out,then manufacture the new one in two (or more pieces) and interlink (don't forget the vent for each) for easier montage in limited space?

 

[Nauti Fox]

I've been looking into it since Assassin mentioned it and it does seem that there are some coatings about that I knew nothing of, like these for instance.
http://www.kbs-coatings.com/tank-sealer-directions.html

The problem I have is that these tanks are nearly forty years old and will not come out in one piece (450 litres) unless the engine comes out first.
I'd need to remove them to ensure a good even coating and if I did go to the trouble of removing the engine then I really would replace them as that seems better than refurbishing the old tank, your experiences noted!

My thoughts at the moment are to cut the top off the existing tank and fit whatever err..fits inside it, I've even looked into fitting bladder tanks inside.
http://www.turtlepac.com/en/products/super-deck-tanks.html

I'm waiting to hear from the insurance company at the moment but would probably opt for a more conventional tank anyway.

Everyone's thoughts are gratefully received, please keep them coming.

 

[Nauti Fox]

How wide is the tank ??

No idea Alf, never been able to get in far enough to see, lost my racing snake build a couple of years ago and can now manage to wedge myself into some fairly large spaces

I'm going to have a better look this weekend as I've got to take the return hoses off anyway, expect I'll be upside down leaving lots of skin on anything sticking out!

 

[capsco]

One problem with fitting bladder tanks is removal of baffles in old tank, you can't really leave any sharp edges for obvious reasons.

 

[Nauti Fox]

I've got a small friend who's good with a grinder!
Seriously though, until I can see how much access there is I really don't know what I'm going to do, this weekend though I'll remove the returns so I can get a new set made up running to the port tank so at least I can still use the boat.

 

[Assassin]

One possible solution is to cut your tank up in situ with a decent jigsaw with metal cutting blade fitted, this way you can cut it into manageable sections without the heat created by an angle grinder, and associated fire risk.

On a friends boat with a similar problem, i did the following:

Tanks were made up in smaller sections as whole tanks, the bottom was drilled for all the required fittings and also fitted with two large flanged pipes on top, the next sections were made in the same way but with flanged sections top and bottom. The base tank was installed in one piece and the next tank gasketed and bolted on top, this essentially formed a series of tanks stacked on top of each other, and as seperate tanks they needed no baffles. Due to the design it made them very easy to install as smaller units, and much easier to work on as they were simply unbolted as sections, and they could ne manhandled by one person into position without removing the engine, and no welding or other hot work inside the boat.

 

[Nauti Fox]

You are indeed wise and know much that is hidden.
Would you still have details on who made the tank for you?

 

[Assassin]

JFM:

These products have been around for many years, particularly the PP Chemical Metal, and i always carry a couple of tubs as it can repair most things such as leaks or damage to castings, and is a good temporary adhesive or gasket.

What and where is the issue with your tank/s?

If its just old age and deterioration you can line it with one of the liquid epoxy fuel tank leakage systems, and if you have reasonable access to your tank you insert a large, soft sweeping brush and coat the sides of the tank with it. If you use multiple applications you can actually build up the thickness of the sides and bottom to form a decent lining as strong as the tank itself.

 

[Trundlebug]

Alternative coating

A few years ago I used this internal coating system from frost
http://www.frost.co.uk/automotive-tanks-products/por15-car-tank-repair-kit.html
when the effects of hygroscopic unleaded petrol took their toll on the 40 year old fuel tank in my Mini Moke in just 18 months after it had been fine on good ol' 4 star for so long

It has worked a treat, although the extensive pre-cleaning and sloshing around was a lot easier with the tank removed and held in my hands, not something that's quite as easy for a boat tank

Good product though.