On November 16th, I decided it was about time I had my radiator out; and have an apparent leak repaired.
It had me fooled from the very start, I observed a considerable rusty water stain on the back of the radiator core, to the right-hand side, and some water had accumulated nearby. However, the core itself turned out to be just fine!
After taking my radiator to Taree Radiators for repair, it turns out, the overflow pipe (which runs down the back of the radiator core) had a hidden hole, which was leaking rusty water onto the radiator core, which then tracked across to the opposite side of the radiator, and it really looked like the core itself was leaking! The bad section of pipe was cut out, and replaced with rubber overflow hose, it's hard to tell the difference, it's all black!
Thankfully, the copper core itself is in perfect condition. The brass tanks top and bottom were also in perfect condition, except for a small crack which had appeared on the top of the top tank, so I had that soldered.
I gave all the cast portions of the radiator a good coat of bitumen paint inside and out, the can says it's good for rusty surfaces and protects against further corrosion, so it should help with longevity.
Iím going to be trialling a glycol-free corrosion inhibitor in my radiator, one which does not affect the water boiling point, which would upset the Model Tís thermosiphon cooling and cause overheating Ė not a good idea!
Does glycol antifreeze affect cooling? Apparently so. Does it affect cooling enough to be a problem with a good radiator? Nope.
It should be noted that the coolant in a properly working thermo syphon system does not boil. The liquid is warmed by the engine, and circulates as needed. Cooler liquid replaces the warmer liquid as it moves from the engine to the radiator. Warm liquid rises, cooler liquid is in the bottom of the radiator and engine inlet pipe.
A lot of people mistakenly think that boiling is a requirement of thermo syphon. This is not the case. Like Steve says, make it easy on yourself, use a good brand of ethylene glycol for best results.
In a thermosyphon system cooler liquid does not replace the warmer liquid as it rises.
Rather the cooler liquid is heavier, and gravity causes the cooler liquid to displace the warmer liquid.
Warmer water does not rise on its own.
Cooler water falls on its own owing to the force of gravity.