Water in Diesel

[Scorcher IV]

Hi,
Started the engine this weekend, it ran for 90 seconds then cut out. After running through all the possibilities I found that I had water contamination throughout the diesel system. I removed the tank sender and using a vacuum pump sucked out water from the bottom of the tank, replaced both filters and bled the system and eventually the engine started and ran as it always has. This was a bit of a wake up call as I had no idea there was any water in there at all. I have had some steam/mist in the exhaust recently but put it down to cold water temperatures however now I wonder if i was picking up small amounts of water from the tank and this is how it was showing itself.

I now want to fit a tube in to the lowest corner of the tank with a fuel valve at the top so that I can periodically draw off from the bottom of the tank, has anyone fitted a pipe into a Bavaria plastic tank and what type did you use? I also intend to change the primary filter body to one with a glass bowl, mine is metal at the moment so no visibility. No idea how the water has got in as I always fill up when back in after a sail and the seal looks good.

[IslandAlchemy]

First thing to do now is get some Marine 16 into the tank, as the water that was there can now cause diesel bug.

Next thing to do is to find out where the water has come from, and I would bet that it's the filler cap/seal.

[SorinCT]

Usually it is the filler cap, either from rain or somebody makes a mistake while filling up fresh water. Can be also tank more then half-way empty and moisture in the air condenses inside the tank and slowly accumulates.
Make sure you prevent bacteria growth because it can lead to a lot of trouble down the line.

[Scorcher IV]

Thanks for the advice, I always treat the diesel every time I fill the tank. The cap seal seems the only way in other than condensation or water in the fuel from the supplier, should have measured while on the boat but does anyone know if the  filler cap is 38mm or 50mm diameter as I will order a new cap seal. I am looking for an easy way to periodically drain from the bottom of the tank without removing the fuel sender which is the only way in at present.

[Fenders]

We had this problem a couple of years ago and ended up extracting nearly 3 litres of water.
As mentioned by Island Alchemy, you need to check where the water ingress is.

On our boat the filler cap is on the aft starboard deck in alignment of the winch. Probably the worst place to put the fuel filler cap. All the deck water flows over the cap as it exits to the rear.
On examination of the cap, the breather hole was clear but the cap when tight is only a mm or 2 above the deck surface. This allowed water to enter the tank.
After changing the filters and cleaning the tank and lines we fitted a plastic filler cap collar made by Perko. This collar raises the cap about 15mm above the deck which prevents water ingress. Very easy to fit and cost about a tenner.
After several years we've had no further issues.
We also use Marine 16.

Fenders

[Yngmar]

Depending on where you fill up, fuel quality is often dubious. Roadside petrol stations have mandatory quality monitoring in the EU, with compliance over 90% except in Greece where it's under 90% compliance. Marine fuel stations are much worse - less monitoring (if any), proximity to water, irregular use (often the fuel sits all winter in a poorly maintained tank) and operator errors. Unlike fuel stations, they're also often independent and thus try to save money by buying cheap fuel from dubious sources themselves.

Fuel delivery trucks (common in small Greek harbours) are totally random - look for ones operated by a big oil company (truck painted in livery, not just a logo stuck on), small independent suppliers are more prone to dodgy fuel. You also sometimes get cheated on the meter

Some people pour all their fuel through a filter with water separator, but as that takes ages, it's usually frowned upon at most refilling docks. It's fine if you fill into cans first and then pour it in the tank on your own time though.

We mostly haul jerrycans because roadside fuel is 30 cent less per litre in Sicily and of reliable quality - and there's not many fuel docks anyways. In Greece we ordered the occasional tanker and learnt a lot about them (like when the guy claims you bought more fuel than fits in your tank, or drags an old rubber hose over your deck, leaving black marks everywhere).

For maintenance, I pump up the dregs from the bottom of the tank by way of a copper tube stuffed down one of the spare fuel take-offs on the tank. Gets in the corners and slurps up the dirt and water. Oh, and the O-Ring on the Roca filler cap gets the occasional bit of silicone grease and replaced when it goes stiff.

We've only had some dirt and never any water since doing the above, but it only takes one dodgy fuel dock or trying to fill up while it's raining

[marioxp]

I am looking for an easy way to periodically drain from the bottom of the tank without removing the fuel sender which is the only way in at present.

I am also thinking to insert tube, through spare fuel take-offs on the tank, all the way to the deepest part of the tank, and keep it. Occasionally connect big syringe and take out water from bottom of tank, until I get diesel.

[Scorcher IV]

Hi Marioxp,

Thats just what I want to do just not sure of the best way to go about it, I am thinking of fitting an additional fuel pick up that drops into the lowest corner, attaching a fuel valve to it and drawing off from the bottom of the tank using a big syringe type thing until I pull out diesel.

Has anyone fitted an extra pick up and what kit did you use?

[tiger79]

I look for water in the fuel tank in the early spring, usually after the boat has been stationary for a while.  I use a rubber priming bulb (as sold for outboards, etc) with a rigid piece of pipe which can reach the bottom corners of the tank.  My tank has a screw-on inspection hatch, and I gain access that way.  I usually pump around a litre of fuel out into an empty 2 litre plastic water bottle, then let the fuel settle for 24 hours.  I can then see if there's any water or contaminants in it (usually, there's nothing).

[Odysseus]

Made my own polishing kit, plus one for every time I put fuel in.

Odysseus
Bav 38

[Mirror45184]

I employ a completely different tactic. As I only do short day trips, mostly return to home marina and prefer to sail or drift than run the motor. So I keep a minimal amount of fuel in the tank. Not more than about 30 liters. During the short period of motoring in and out of the marina the recirculated fuel heats the small quantity in the tank which helps to keep moisture out of the fuel.