Has anybody cut through the head of an old Q4 exhaust valve with a hack saw?
What I am trying to determine is if these valves are sodium cooled or not. The exhaust valves from a TS engine is not and is solid.
The head of a sodium cooled valve is hollow. In the hollow is strings of what look like lead. When the valve heats up to a certain temperature the lead-like sodium pieces change from a solid to a fluid, it may even a a later stage turn to a gas. But by changing form/state(langauge) the sodium use some heat energy and this energy is then not available to heat the valve further.
On a sodium cooled valve care must be taken in the way the valve is modified. You can easily weaken the valve and have the head break off during operation.
Mere interest, put some of the sodium bits in a glas of water and see it bubble.
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