THE WATERY SAGA

Could I disassemble it? What would I find inside? Was it worth the effort? What a challenge! Yes, as any red-blooded engineer would do, I decided to test the mettle, so to speak. First attack was with a stiff wire brush to remove the barnacles, mud and aluminum oxide. Eventually I got to bare metal in places and saw the pock marked surfaces. Not looking good! With a fine metal brush I worked around the heads of the well-rusted bolts - here would be the main event. After a fair bit of prodding and poking I was able to clean (reasonably) the hexagon cavities in the bolts. I then tapped in a straight Allen key that is made of high-speed steel (same material as a high quality drill bit if you’re not familiar with metals) that has the hexagon section machine ground on the end - very precise fits. By heating the surrounding aluminum alloy, tapping the key as I applied turning pressure, I could sense some success. Eventually I was able to remove the two rocker box bolts. All in all, I removed all but one head bolt and it snapped off due to the alloy and steel corrosion locking it firmly in place. (I dealt with this later as I will explain). The rear cover and the cam case cover bolts were not too obliging but a bit of heat and a small pair of vice grips put them in order. As all the case joints were well corroded together I did not want to force the issue so I dunked the engine in some white vinegar (4% acidity - sold as ‘salad vinegar’- about 30p per litre) and left it for about 24 hours. Cleaned it off in some warm soapy water (neutralizes the acid - soap is alkaline) and tested the grip of the case covers. Both the rocker cover and the back cover came away good as gold and.... poured water into my lap in an embarrassing spot. (“A little accident, dear?”) All cavities inside the engine were full of water and that had me thinking. These engines are totally sealed with sealed bearings and the breather connected to the intake. Okay, think a bit. Water went up the intake, down the breather tube into the crankcase. A chance in a million that both valves would be closed when the engine stopped so one valve (or both on the overlap) was open allowing water on top of the piston and air out. Over the period of immersion the water would slowly seep up the valve guides and fill the rocker chamber which would complete the picture - every cavity full and now soaking into an unmentionable section of my lap. My first examination was the rocker area - all the steel bits immersed in water for 11 years. What a picture!

THE WET 120

I rang Tim (the owner) and asked if his memory was good enough to remember the advice I had given him before he gave the then new engine its first run. “Err, umm, argh...YES - I do remember! You told me something serious would befall my person if I used anything other than Cool Power in the engine. Why do you ask?” I told him that the rocker equipment, valves, springs, push rods and such were as good as new and still coated with oil. In fact the oil from the fuel was in a layer in the two tanks (main and hopper) separated from the methanol and nitro due to the rather excess amount of water absorption. The blue color had now changed to a weak yellow which is typical of this oil when left in water (tests I have done in experiments with water in fuel). As I progressed with dismantling the engine I found the same story throughout. Even the ball bearings were totally free of corrosion. All I found was a slightly moth eaten area around the little end of the conrod and this was due to electrolysis action. Here we have aluminum alloy (a mix of several different metals), bronze alloy (another mix) and steel (again, a mixture) in a watery soup creating an electrical current and so setting up a galvanic action. This resulted in a few moth eaten cavities in the little end. All in all I ended up with a seized carby (all aluminum alloy subjected to constant water flow), a prop driver that looked like it had advanced tooth decay, reshaped (by corrosion) prop nut and washer and a load of reasonably useless caphead bolts. The rest of the internal parts were just as they were when new. As Tim did not have a need for the gear pump in the backplate (it still works perfectly) and that a new carby was needed I fitted an E carby (non pump), manifold and backplate, new conrod, prop drive, nut and washer and a complete set of new bolts. Using a slot drill I bored down where the head bolt shank was still locked in with corrosion in the barrel fins, re-tapped the hole 5 mm, screwed in and chemically welded a 5 mm stud then drilled down into this and tapped it for the head bolt. Although a bit ...err...shall we say...err... untidy on the outside, thanks to O.S. for the high grade machining, fine surfaces, first class materials and to Morgan’s Cool Power oil for protecting them I now had an engine assembled and ready to run. On the bench, (my) normal starting procedure for a four stroke, one flick and away it went as if nothing had changed from a moment before it took the deep dive. I must say it even gave me a little joyous pride to see it running so sweetly considering what it looked like when Tim found it on the bank of the dam.
While I certainly don’t recommend it, if you have this strange passion to leave an engine under pond (or other) water for several years, you have a better chance of bringing it back to life if it is an O.S. and you use Morgan’s Cool Power oil in the fuel.