No, I don't think it has been in a flood. No other signs of any water damage. No rust, no mud in hidden crevices, no water marks on anything.
I also wonder about the algae. I always thought algae needed sunlight to grow although I am taking all comments into consideration. What kind of algaecide do you put in the hydraulic fluid that would be compatible?.
You are correct, algae does need sunlight to grow... unfortunately many in the tractor/diesel community refer to a diesel
biological growth as "algae". It's inaccurate, but there you go.
A biological growth in the diesel tank (plus fuel system/fuel bowl) feeds on a layer of water, which is on the bottom of the fuel tank as water is heavier. If you were to put an inspection camera down into the fuel tank (which I recommend that you do), a biological growth will look like fairy-floss (cotton candy) mixed with phlegm. You will need to dose the tank with a
diesel biocide, which is readily available at any auto-parts shop/store.
Then you'll need to drain the entire tank and wipe out the dead biological growth using a 'grabber' (auto shop again) and many CHUX (J-Cloths). The dead biological growth will be stringy and brown.
I'd also wipe out the entire fuel bowl assembly. Only then would I add fresh diesel to the tank (+ this "seafoam" additive) and fire up the engine.
I have no idea what has contaminated your hydraulic filter.
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Oh, and by the way Mate; g'day and welcome to TBN from Downunder.
Enjoy the site.
