I always keep my 100L diesel fuel tank full - except for the past 12 months on the hard stand when it has been nearly empty.
The fuel I drained today from the Raycor filter drain point and the fuel I drain from the fuel tank sump drain appear perfectly clear with no sediment. I did, however, notice a slight red tinge to the fuel I drained from the filter but again no sediment.
I'm concluding that I have no condensation in the tank, no "diesel bug" and intend to re fill the tank.
But first a couple of questions for diesel mechanics or other knowledgeable persons :
(1) what colour and texture is the "diesel bug" ?
(2) I rinsed the filter in petrol then methylated spirits. No sediment or other muck appeared so the filter seems fine. Is it acceptable practice for me to re use the filter (just in case the re fill process creates a problem so I won't wreck a new filter) ?
(3) the centrifugal disc in the Raycor filter has not moved since it was installed. I've always assumed this was because the filter was just too big for the 3 cylinder 27hp Yanmar engine and so I did not view this as a problem. It this a reasonable conclusion?
(By the way.... although on the hardstand I always run the engine for 15 minutes every couple of months. It will be on the hardstand for another 12 months).
Here's a photo of my Racor filter showing some brown sediment (only dirt I hope) on the turbine centrifuge (just looked up the correct term).
I'll be flushing it out tomorrow.
Thanks for the link HGO2. Those are some pretty grim photos.
The 15 minute run would be the main concern.
Nothing would get hot enough and there would not be enough load.
Be glazing up and the impurities in the oil would not burn off.
Sorry
I run my diesel e Friday or Sunday for one hour in gear or I chuck the lines and head to the islands. The trick is to keepthe tank full and change your filters. My nightmare is to suck water. From my tanks.
Select to expand quotelydia said..
The 15 minute run would be the main concern.
Nothing would get hot enough and there would not be enough load.
Be glazing up and the impurities in the oil would not burn off.
Sorry
You can avoid glazing by keeping the revs up - a bit under half should do it. I had a farm and earth moving and a bus and truck run so had more diesels than I can count. I glazed a D4 that had neither the load nor revs when it was driving an irrigation pump. Re-gearing to increase the revs cured the problem and really, diesels hate running slow even under load. Low revs and load equal carbon, low revs and no load equal glazing.
I had the diesel bug in an AEC bus and it was a major strip down of the whole fuel system at big cost, so it really makes sense to treat your fuel.
I agree with Lydia, 15 minutes every couple of months is too short a time to heat the engine to burn off products of condensation that accumulate on the cold internal surfaces.
Diesels are made to work. Used to run a fleet of trucks and as long as the thing was used every day all day, and serviced regularly, there were no major problems. When it got laid aside for whatever reason, seals started to harden, fuel, oils, filters deteriorate, start to leak and eventually die.
Regular use and regular service is the ducks guts.
Good sounds like everyone one in here changes there undies regularly 
The bugs a bit like a cold it can start at shipping and continue along right through the the fuel delivery system
When I buy diesel I always try to buy it from a high volume outlet
Select to expand quotezilla said..
I always keep my 100L diesel fuel tank full - except for the past 12 months on the hard stand when it has been nearly empty.
The fuel I drained today from the Raycor filter drain point and the fuel I drain from the fuel tank sump drain appear perfectly clear with no sediment. I did, however, notice a slight red tinge to the fuel I drained from the filter but again no sediment.
I'm concluding that I have no condensation in the tank, no "diesel bug" and intend to re fill the tank.
But first a couple of questions for diesel mechanics or other knowledgeable persons :
(1) what colour and texture is the "diesel bug" ?
(2) I rinsed the filter in petrol then methylated spirits. No sediment or other muck appeared so the filter seems fine. Is it acceptable practice for me to re use the filter (just in case the re fill process creates a problem so I won't wreck a new filter) ?
(3) the centrifugal disc in the Raycor filter has not moved since it was installed. I've always assumed this was because the filter was just too big for the 3 cylinder 27hp Yanmar engine and so I did not view this as a problem. It this a reasonable conclusion?
(By the way.... although on the hardstand I always run the engine for 15 minutes every couple of months. It will be on the hardstand for another 12 months).
For the price of a new filter you get peace of mind as well as an engine that will run as it should. There is nothing worse than having the engine stop dead at the most inopportune time, like entering the heads at Botany Bay with an incoming tide and 30 knots of southeasterly wind.
Those pics posted of the bug are what happens, oh how I wish I didn't know!
The cheapest place that I found raycor filter elements was Western Filters in Sydney, they also flog a fuel additive " Fuel Doctor " that I have been using and found to be good.
Hope this helps, cheers.
If you're only starting your engine every month or two add some Chemtech to your tank, will keep diesel good for many years.
www.supercheapauto.com.au/
Beware of running diesel engines unloaded. I saw a 500kw gen set drive engine distroyed because it was run under loaded. These Diesel engines run at 1500 rpm no matter what the load. But if you run them unloaded it will glaze the bores. The sealing rings on the piston are designed to expand under pressure. The pressure increases as the load on the drive shaft increases and has bigger all to do with the revs.
And just to clear up another furfy, the load from an alternator is not enough. A 120 amp alternator would require about (or less) 3kw of engine power.
And as usual, I could have it all wrong. But I'Ve worked with a lot of diesel fitters and the 500kw gen set saga was not a good way to learn this simple fact.
