It’s called rust Usually near the sealing ring in the base of the block.
Sorry, if I sound thick, but this is because lack of antifreeze causes ice to form within the engine, which distorts the block in some way, allowing moisture to enter and rust to form...?
The problem is that water always has some dissolved oxygen, this reacts with the iron in steel to form rust (iron oxide), to prevent freezing you add antifreeze to the water, but ethylene glycol doesn't on its own stop this process (it does lower the melting point) as was discovered a good time before Major's were around. This was solved by adding corrosion inhibitor, now you have the coolant that you will find in any engine, there are many types but they all use water, an antifreeze and a corrosion inhibitor.
The o-ring slot gets corroded from above, eventually this gets through to the o-ring, allowing it to expand and stop sealing. This then means the liners need changing and the block needs work to make the new o-rings seal.
Sandy
The o-ring slot gets corroded from above, eventually this gets through to the o-ring, allowing it to expand and stop sealing. This then means the liners need changing and the block needs work to make the new o-rings seal.
Thank you Hywel and Sandy.
Not been a good day for spannering. Decided to be sensible and tighten the screws holding the exhaust onto my chainsaw to the proper settings with a torque wrench. Head of screw sheared off and now I have to get the shank out. Going to be one of those weeks I think.
That's a great visual explanation of cylinder liner cavitation. My suspicion that this was going to be one of those weeks was only strengthened by the shock arrestor next to the hot water cylinder in my house spontaneously developing a high-pressure pinhole leak, resulting in a mini flood. I wonder if the mechanism by which it occurred is similar to that driving cylinder liner cavitation.
So the focus has moved from Fords to Fordsons. Not much in the market at the moment, it seems.