Apparently molasses works really well in fuel tanks, not just for rust but also just for breaking down general gunk buildup.
 

I might try something like kero as I'm a bit worried about using a chemical based degreaser because I cannot get inside the tank to scrub it clean afterwards and not all of them list what nasty ingredients they use on the label. Molasses is a good one too, seen that stuff work magic before, will be my backup, back yard plan :D

Then, to finish off, air blast to get the bulk of the water.  Finish with a litre or so of methylated spirits to absorb what remains . . .

G'day Knightrous,
 
I used molasses and hot water to clean the tank of my blue adub, which was horribly rusty. I let it sit for about a week and then rinsed out, swished around some metho etc. Did a pretty good job too, just depends on how bad your tank is to begin with. After seeing the blue one, I pulled the tank from my white one, which thankfully was completely clean.

Interested in seeing how this goes. your ideas are abit out there but are good ones.

O-ring is in the planning, need it to seal the oil from the water channels anyway :)
 

5SGTE
Er I actually have one of these sitting in my shed doing sweet FA I could've sold you for less than 400-600...  BTW from my experience with it, your not going to need a thermostat but think mine was ~300mm so your about 30% larger.

Just buying one wouldn't be any fun and certainly wouldn't make me utilize the tools I have. Why buy fish if you live on a trawler! :D
 
I've gone the thermostatic plate for two reasons.
 
1. The stock AW11 oil cooler is a by pass cooler. This basically bypasses excess oil pressure into the oil cooler before delivering it back into the sump. Effectively it's not actively cooling the oil entering the block.
2. Another AW11 owner installed the a laminova based oil cooler into his car and found that it was working too effective and the oil temps were only just getting to required temps.
 
So I happened to come across the thermostatic plates cheap on Ebay ($110!) and grabbed a pair in a flash.
 
Anyway, another session on the lathe.
 
Turned down the water inlet to 36mm, will turn it down further once I double check the size of the radiator hoses (34mm..?)

 
Then I turned the inside steps to suit. The first step is where the inlet presses over/up against the tubing, the 2nd step is where the O-ring will go, this is still to be machined to final size (~39.5mm). The third step is where the core inlet butts against and the final one all the way down the bottom is only there because my live center is only 20mm in diameter and if I bore it out, I wouldn't be able to recenter the job in the lathe again.

 
Everything press fits with just a gentle love tap of the knockometer.

 
And the core sits flush at the other end!

 
 
Now back to another project, I dropped my C60 gearbox in today to the local mechanic to pull the 5th & 6th gear clusters apart due to my gear puller being weak sissy fail! When that comes back, I can finally finish off my 6 speed gearbox + LSD project!