Not sure why, but I got thinking about sodium-filled exhaust valves. I know that they were common in large aircraft engines during WWII as a way to cool exhaust valves, the valve stem was hollow and filled approx 50% with sodium, and as sodium becomes liquid at 208F, its presence inside the valve stem aided in transfer of heat from the valve head when it became hot by basically sloshing back and forth within the valve stem and transferring heat away from the valve head.
I was wondering if sodium-filled valves were still used, and a quick search on the internet brought up, no surprise, an article by KC on just this matter!
https://www.cycleworld.com/story/bikes/some-facts-about-sodium-filled-valves/Many years ago, about 52 years ago to be approximately precise
(I know, an oxymoron) a buddy and I learned through the local grapevine that an excavation crew working on an oil pipeline in the North Sea off the east coast of England had uncovered an old aircraft engine. They put it to one side on the muddy flats of the shoreline and continued with their laying of pipeline. The grapevine information was that it was a Rolls Royce Merlin engine from a Hawker Hurricane, or possibly an early Supermarine Spitfire.
This was before the days when such things had sky-high dollar value, restoration of such things was a thing of the future, and an aluminum
(aluminium?) engine like this that had lain buried in the salt water mud for 30 years would probably be of little interest to anyone anyway. We waited several weeks, maybe even a month or two, and having not heard of any specific organization or authority having shown any interest in the engine my buddy and I decided to drive out to the area and see if we could find it. I'm not sure what we intended to do with it, I think we maybe thought we would load it into our vehicle and bring it home!!!!
Having learned the approximate location of the item from local lore, we drove the 20 or 30 miles out there and did eventually spot the engine. The coast in that part of the world slopes extremely gradually and tides are as much as 35 ft and go several miles out.......meaning the difference between high tide and low tide can be 2, 3 or even 4 miles. We arrived at low tide and using binoculars the engine was quite obvious, it stuck out like a sore thumb as a dot in the distance on the muddy flats of the recently sea-covered shore.
We had purposely borrowed a 4-wheel-drive Landrover with thoughts that we may be able to drive right up to the engine and somehow haul it into the back of the vehicle
(A 27 liter V12 Merlin weighs nearly 1,700lbs.....the naivety of youth is just amazing!) but it was quite obvious that where it was located we had no chance of driving up to it anyway, and it would take considerable effort, equipment and determination to get direct vehicle access to it.
So, we drove as close as we dared in the Landrover, and then walked the extra 1/2 mile or so to the engine. It was relatively "complete", we assumed the structure of the aircraft had been so fragile and decomposed that the engine was the only solid item the pipeline crew thought worth salvaging as they moved it out of their way and placed it on the sand/mud flats.
The remnants of a two-bladed wooden propeller stub was still there indicating it was an early model as three-bladed propellers were not fitted until after 1939, and metal, constant-variable ones even later. At first glance the engine looked in remarkably good condition considering its location and history, but our thoughts of salvaging the motor complete were dashed when we realized that despite the high quality metal parts being in relatively good condition, the basic aluminum structure of the engine had been compromised by years of exposure to salt water.
I was a little surprised at the size of the engine, the valves and valve springs were exposed as the aluminum valve covers had long since been eaten away, and the valve springs were rusty, but the valve stems were still shiny bright!. Once we realized the extent of the salt deterioration there didn't seem to be much that would be salvageable , but I did wonder if I could remove some of the 48 valves complete with springs......... I had a wild idea that they would make great chess pieces! I tugged on a valve spring and it came away in my hand, complete with collets and valve, I repeated this for several others, some gave way easily, others resisted. It was cold, the wind was blowing, we were getting tired and disappointed that we weren't going to go home with a complete V12 Merlin engine in the back of our Landrover, so I tugged about 4 or 5 of the valves which offered the least resistance and we left with some complete valves and valve spring units.
Those valves made for interesting talking points for many years, they were made of Cobalt and were as shiny as the day they were made despite all those years in salt water.
Anyway, a rambling story which started off about sodium-filled exhaust valves.
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