Looking for a second (or Third) Opinion on Intake Valves.....

[Reflex]

After finishing up Phase I, I decided that I'd pull several things apart and do a good inspection before moving forward. Part of this inspection was a compression test and borescope pictures.

The compression test came out very well at 79/80 on all four cylinders. However, when I got to working with the borescope, I found a couple of anomalies. At issue is a couple of what look like burn marks on the intake valves on cylinders #3 and #4.

I subscribed to Savvy, sent the pictures in for each cylinder and all came back as "Satisfactory". I sent a note back asking them to take another look at the intake valves on cylinders #3 and #4 and got the following reply back, "Intake valves generally do not burn, the spots on these valves are likely fuel stains that occur after the engine shut down".

The pictures I sent to Savvy are below.

• IO-390
• 40.1 Total Hours Tach Time

Thoughts?

 

[RNB]

My snarky ish thoughts are
-79/80 and I'd mostly ignore all else
-Savvy satisfactory good enough for me
-then they explain the color

Stop testing and looking for $h!#!

I used to work in healthcare, would at times think of a full complement of tests and procedures to offer patients so they could fret over more stuff when they started going down this kind of route.

I really would not think to scope a new engine.

I'm a bit OCD and this stuff would weigh heavily upon me. I made lots of management mistakes on my first plane with excess maintenance/upgrade/repairs, now I hope more reasonable.

 

[lr172]

not burn marks. The intake valves are relatively cool, so they collect deposits from additives in the fuel left behind after combustion. These are usually whiteish to light grey and that is what I see on your valves. This is a dry powdery coating. However, a bit of oil got on one part of the valve. This oil absorbed into the powdery deposit and changed the color/shade of that deposit. This is like spilling a drop of water on a piece of paper and that area appears to change color/shade.

Some oil is introduced at the valve guide. some of this oil drips down the valve stem and proceeds to wrap around the tulip area and some works its way to the valve face. Once it hits the deposts, it is wicked in.

Larry