Diesel deterioration

pugwash

pugwash

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Friend has a boat ashore in Malta and has to leave it for a whole year. Tank is full of fuel. Can he leave the diesel in situ and expect it to work okay when he's in the water again? What steps should he take? Tank is full enough to discourage condensation.
 
Bearing in mind there is probably some water/muck in already I would suggest, on return drawing some fuel through and swapping the filter before going anywhere.
 
Re: Diesel deterioration - no problem .....

just make sure vents are "meshed" to prevent ingress of wee timorous beasties !!

As to "Don't try this with unleaded tho' " ...... only difference is that it would be better to drain off into sealable containers and store in cool dark place. Other than that .... no problem.

The only time I would suggest caution really is when a boat is filled up with diesel in summer and then lifted out onto hard for winter ... when possible temps drop to -5C or lower - then you get CFPP / Cloud Pt problems ... If boat stays in water ... generally the sea-water temp around boat keeps temp up enough to not be a problem.
 
Re: Diesel deterioration - no problem .....

[ QUOTE ]
......... lifted out onto hard for winter ... when possible temps drop to -5C or lower - then you get CFPP / Cloud Pt problems ...

[/ QUOTE ]

Definitely won't be a problem for Pugwash's friend. The boat is in Malta. For us down here +5C would be terribly cold! /forums/images/graemlins/smile.gif
 
I know ...

I thought I'd add the comment for benefit of our more Northern friends ....

Think about my boat ... nicely snug on her mooring in UK ... will be lifted along with Prime Solent Barnacles ... trucked to Latvia and stood through winter ... some days dropping to -30C ..... poor old Red Diesel on board .....

Will have to add some of my jungle juice from work !! Along with the frost protect heater on board ... (bet that'll really make a difference !!!!)

Bet the old Barnies will sit up and take note !!!!
 
Re: Diesel deterioration - no problem .....

Could you expand on this? My normal practice is to fill the tank in the autumn, finally topping it fully up from bottles after winterising the engine and changing fuel filters once ashore. I'm on the west coast of Scotland, so not very cold, but there is the odd low temperature excursion. So far I've experienced no problems, but am I missing something?
 
Re: I know ...

I have a 12 gallon diesel tank on my boat which has about 7 gallons in it. I was going to top it up but should I add, say, 1/2 gallon of petrol to save it going cloudy? The boat is out of the water until 1st April.
 
Re: Diesel deterioration - no problem .....

It's a phenomenon known as 'waxing'. At temperatures below about -5C, as sbc says, waxes tend to drop out of diesel fuel, when they can block the fuel filter and severely hamper engine operation. Once the temperature recovers to something more amenable, the wax redissolves in the diesel and no harm is done.

The traditional method overcoming this, used by truck drivers all over the world, is to include a small amount of petrol in each tank of diesel. Fuel sold in UK and much of western europe is graded as 'summer' or 'winter', the latter having a solvent in it to delay the onset of waxing.
 
Cold weather properties ...

Normal Red Diesel and summer quality road ... is about -6C ... -8C CFPP .... (CFPP = Cold Filter Plugging Point). It's the point that crystals start to form in the fuel as parafins and other components start to drop out.
If the fuel is in such low temp for reasonable time ... then it may have sufficient crystals formed to block your filters and cause engine to not run.

The normal remedy is to have the fuel "doped" for this characterstic before it reaches the "supplier" ..... that's the stage that my company acts ... We inject additives to 000's tons of diesel before it hits market. You can check this with ref. EN 590 by Google ... which details the quality specs for different climate conditions / markets etc.

The spec for UK market EN 590 for winter use is -15C and occasionally / dependent on location could be -20C or lower ...

Reason I mentioned it - is that a boat sitting in water or temperate area would not normally suffer unduly ... short spell of cold and then warm up again is usually OK ... Given reasonable warming the parafins etc. would disperse into the fuel over time so as you found - you have no visible problem. But a boat that is lifted out onto an exposed hard could be subject to lower temps than where water is surrounding and "keeping boat temp up" - then it is possible that this CFPP point happens ... if the engine was then run and not cleared ... the filters could then be blocked ... etc.

You can in fact visually check this by taking a sample and placing in a clear sealed bottle ... leave it outside and when temp drops to about -5C or lower - the Cloud Point will act .. where the fuel will "cloud up" to a milky off-white ... and as it goes lower deposits will form in bottom of the bottle.

Ok ??
 
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