TSIO 520 Exhaust Valve

[slowflyin]

Folks, need some assistance.  This jug tested 10/80.  Air out exhaust.  Doesn’t seem burnt.  Other five jugs had the typical pizza look.   Burns 1 quart between oil changes and flys 30 hours per week.  450 TT  on engine.   Runs like a fine watch!  Tomorrow I’ll measure but initial observation was the valve feels sloppy in the guide. Thx. Joe 

[N201MKTurbo]

You can see that there is a hair thin contact line on the far side of the seat. Something is causing that valve to seat poorly. You caught it early, but I don't think it is long for this world. If you were to pull that cylinder, have the valve inspected and if it is within spec, change the valve guide and grind it back in. You could fix it cheap.

[Cody Stallings]

If that’s Lead on the seat like my 520 had, a little Valve Grinding Compound, Drill, Fuel hose an Patient Mechanic can fix it

Had a Cylinder that was 15/80 an spooling the Turbo up, to 72/80 an quiet exhaust pipe in a couple hours.

Very satisfied, except for the pep talk about run it leaner. Which I do now an Borescope is showing less deposits in the Cylinders an the belly stays cleaner longer

[carusoam]

From the cylinder side of the valve...

We are always discussing the uniformity of circular patterns around the valve... Nicely round with rings, looking like a pizza with a nice crust...

When a valve starts to mis behave.... there is often a hot spot radiating out from the edge of the valve... Breaking a piece out of the crust image looking beauty...

This occurs when the valve doesn’t rotate smoothly and distribute heat evenly all around...

So with no compression... something isn’t working very well... but it hasn’t been mis-behaving very long it seems...

Of course this is PP thoughts only... not a mechanic...

+1 on cleaning, reaming, resurfacing, valve work mentioned above....
 

Best regards,

-a-

[slowflyin]

Thanks for the suggestions!  Update- lapped, staked, lapped again. Tested hot every time. Still only 16/80.  Valve guide is toast.  Typical side step when the valve closes.  At TDC with air on I can push the exhaust valve spring laterally with my palm and dump the pressure to around 5/80.  Pulling the jug Monday.   Not very impressive longevity.    

[carusoam]

That was fast, Slow...

 

Which plane are we discussing?

Got the Bravo mods with that? (Avatar mentions M20M)

Make sure the wet heads are distributing oil properly while you have it off...

Confused PP thoughts only, not a mechanic...

Best regards,

-a-

[kortopates]

Just now, carusoam said:

That was fast, Slow...

 

Which plane are we discussing?

Got the Bravo mods with that? (Avatar mentions M20M

Make sure the wet heads are distributing oil properly while you have it off...

Best regards,

-a-

I wondered what airframe it was too, but the OP is referring to a Continental engine. If it was a Mooney it would have to be a Rocket, but I'd guess its something non-Mooney.