EGT Gauge in a T800

[Hammerhead]

(09-23-2017 )Rawze Wrote:  

(09-23-2017 )Hammerhead Wrote:  ...
I'm boroscoping my cylinders trying to find why it appears I've sunk a valve in the last 6 months, and sending the pics to Rawze and discussing my findings on mumble with him
...

I think you were worried about this scenario ...

Reference post... http://rawze.com/forums/showthread.php?t...66#pid9466


But your boroscope video revealed this ...



I remember that. I suggested that it was more likely a rocker shaft out of adjustment than 3 sunk valves. The boroscope also revealed that the contact surface area of each valve looked good too, and that none of them looked like thay had actually sunk. - How did that turn out btw?

Your first pic is exactly what I was afraid of.
What did you use to overlay the outlines of my (or is that one of yours) boroscope pics?
That is frickin AWESOME!

As discussed at the time, and I have no idea how it could have happened other than a bizarre sequence in the heating and cooling cycles, the front valve rocker shaft had a torsional twist in it.
During disassembly and countless measurements, every valve measured within thousands of each other, which was easily within tolerances of the measuring devices being used. We agreed after close inspection of my boroscope pics and vids that the valves and seats looked great as best we could see. So I reassembled the front shaft assemblies and ran the overhead, and all three front cyl Jake dial indicator measurements were within a couple of thou and back to normal.
So the only conclusion was the rocker shaft was torsional twisted, because the change after reassembly was greater from rear to front, and torsional rotation is the only way that can happen.
I've popped the rocker cover after the very next two loads, and dial indicator measurements have not changed.
THAT is a new one on me for sure!

Since I'm sitting around killing time anyhow, I should do a write up on that whole situation so others have a reference...