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Diesel bug


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Flush and drain with fresh diesel as much as possible, get a good diesel bug additive and use it from now on, but the main bit:

Install a good glass bowl diesel water seperator (filter), and if having your engine running is mission critical, install 2 with valves so if one fouls up, you can switch to the other with the flick of 2 valves.

A good filter should be about $150, but all the fittings to put in 2 can add up quick. You may also want to be able to bleed your engine super quick and easy. I've installed an outboard motor fuel priming bulb. Cost about $15 and super quick to pump diesel through, 10x faster than the little engine fuel pump...

We've had the bug, it is a major pain in the arse. We pulled the tank out for a thorough clean. You will need to learn to live with it, hence the need for 2 filters (I think), the biocide, and as much flushing as possible.

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Drain and flush,install water trap/filters, as Fish Said outboard bulb works well,Buy fuel where there is big turn over and use a biocide and where possible leave tanks full.

Leave it and it will get in to your pump injectors etc

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My other tank can access the top. So like to cut for a inspection hatch.No mains power.Have 18v Ryobi grinder(but thats sounds a nono)Buy a Ryobi jigsaw?Are they good for cutting stainless?

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15 hours ago, harrytom said:

Tank should be removable in most cases as they do get pin holes now and again,really should remove and flush.

I'll agree with that. Developed pin holes in the fuel tank on my Cav 32. Had to remove the engine to get the fuel tank out. Had the same happen in my present boat, tank is in under saloon seat. 

Undo the hold down fixings and lift out. Couldn't be easier.

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25 minutes ago, chariot said:

I'll agree with that. Developed pin holes in the fuel tank on my Cav 32. Had to remove the engine to get the fuel tank out. Had the same happen in my present boat, tank is in under saloon seat. 

Undo the hold down fixings and lift out. Couldn't be easier.

No idea why designers/builders put tanks n things in unaccessable places,cav 26 fuel tank under rear of cockpit and could slide out via quarter berth same for water

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1 hour ago, lateral said:

My boat always smelt slightly of diesel until l glassed over the ss tanks with flexible epoxy. Made them removable at same time. Hoping never to have to go back there....

where do you guys vent tank to? I went to under coaming  in cockpit. Need a a fitting though.

Live in fear of bug.

Vent at aft end of cockpit halfway down to cockpit sole and only about 40mm out from the front of the cockpit seat so you bash your knees of calfs on it. Only about 400mm up from cockpit sole.

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1 hour ago, lateral said:

My boat always smelt slightly of diesel until l glassed over the ss tanks with flexible epoxy. Made them removable at same time. Hoping never to have to go back there....

where do you guys vent tank to? I went to under coaming  in cockpit. Need a a fitting though.

Live in fear of bug.

Aft end of cockpit about 400mm up from cockpit sole and about 40mm out from the front of the cockpit seat so you can't skin your knees or calfs

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Diesel bug requires water to survive. SS tanks are the worst,  as they condensate on a cold day when warm diesel is returned from the engine. These days, most production boats use plastic tanks, which helps. Better still, is built in fibreglass tanks - the box section can add structural integrity to the boat, where as strapped down tanks reduce it.

Best place for a breather is central and high up on the transom - fumes go overboard, less chance of water ingress.

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2 hours ago, chariot said:

If i have 400mm of water in my cockpit with 2X50 drain holes the last thing I am going to be worried about is water ingress into a fuel breather. 

A single wave can do that. Ever been pooped?

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2 hours ago, harrytom said:

solution easier than you think,use the boat and keep tank full,

Exactly what I do. Top tank up after every outing.

 

1 hour ago, Island Time said:

A single wave can do that. Ever been pooped?

No, never been pooped, but never been offshore. Done sh---t loads of coastal but never have that volume in the cockpit.

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I my view, in nearly every tank installation, there is a design flaw. The Fuel line does not come from or go down to the very bottom of the tank. The idea is that it then does not pick up water. That is just fine and dandy if there is another way to empty the tank of water on the bottom.
As said in above posts, the Water is actually where the Bug lives. The Bug can be either Algae or Bacteria or both even. Both live in the water. Algae does not need Diesel to live on. Bacteria feeds on the Fuel. Very simply, remove water and keep it out and you will never have a problem. (unless you introduce dirty fuel from a contaminated supply).
The best idea if it can be done, is to have a part of the bottom of the tank that is lower and water will eventually run to and accumulate. A drain tap fitted to that low point then allows removal of water. Then next best is to have the Fuel line run to the bottom and have a really good Fuel/water separator. Good ones like Racor are very expensive. You could be spending in the realms of $300 and much more depending on size. The filter elements are not expensive and are high quality and you can now get elements that are hydrophobic, so water will not pass through at all.
You need to keep regular inspections to ensure water does not accumulate in the filter. Racor also has a bowl that will send a signal to a light or alarm if water fills the bowl.

The simple fact to remember is, No Water, No Bug.

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Agree Wheels. Another option if you have a tank with no drain at the base is to have a bung inserted directly above the low point, o. The top. Then, if there is any water in your separator glass bowl, clent it, then remove the bung, put in the tube from a vacuum oil extractor,  right to the bottom of the tank.  Suck it out until only clean diesel comes out. 

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