T Mack 1 - FSO wrote on 01/04/08 at 10:31:50:On the seat face???? Carbon build up, two reasons, too much gas or trying to burn oil..... (Yes - No ????)
Brainstroming here:
I thought the face gets "cleaned" everytime the valve closes. In other words, the seat gets wiped off by the movement of the valve on it at contact.
If the guide seal was leaking, wouldn't the carbon be a tiny bit greasy around the immeidate area? But then again, I guess the exhaust gas temp would be enough to dry out just about anything.......
Next..... if the seal was leaking, would the carbon get the chance to get to the valve "seat" durning the exhaust stroke? Wouldn' the gases push/pull it down the pipe?
First off, we can eliminate gas as the source of the carbon. The carb, petc0ck, tank, and all that is just fine. As well, I'm actually running leaner than most with a 152.5 main.
Yes, carbon on the seat face. On the ground sealing surface.
Yes, I thought the seat would be cleaned by the valve operation (though it should be burning clean anyway).
The area "beyond" the valve seat has a generous build-up of carbon in the port...the port that was spotless 130 miles earlier.
I, too, figure that oil leaking through the valve seal would be blown out the exhaust and never enter the cylinder. In fact, I always thought that leaking valve seals only leaked "a little bit" from gravity after the engine was off anyway...and smoked a bit on startup.
SOooo, it would seem that the oil must entering the flow
before the exhaust valves rather than after them. Right?
Still sound like rings/piston/cylinder?