Valve damage

[stopintime]

Once in a while I enjoy my engine, but seldom for long...

Now it won't start easily or idle well.

Dealer mechanic thought he could see a gap in the intake manifold (?) and starting fluid proved him correct.
Turns out the engine builder didn't bother to install O-rings.
Installing O-rings didn't help, so...

Leak down test at horizontal 2% 
Leak down test at vertical 90% 

Theory is that false air has created a combustion chamber environmnet which is 'eating' valves.
Plugs were fine though - maybe a little less chocolate than desired, but the same on both cylinders.

Dropping the exhaust valve low enough to see it through the plug hole shows a piece missing.

I will pull the head tomorrow to inspect further.

(will I need to remove the cam cover to get to the head nuts?)

[koko64]

Sorry to hear. Absolute shame.

A ground down ring spanner may fit with some wiggling.

[ungeheuer]

Bugger.

Sorry that your beloved machine isn't returning the affection 

Hope it's not too gruesome once you get in there.

[stopintime]

Some light scratches on the valve seat - probably repairable without removing/replacing it....

At the moment there are conflicting theories about why and how this happened 

[ducpainter]

The pitting on that valve says pretty hot to me.

You need a bigger motor...or a new engine builder.

[stopintime]

The pitting on that valve says pretty hot to me.
..............

Interesting observation 

.........
You need a bigger motor...or a new engine builder.

Probably both 

[koko64]

Quite a chip with sharp edges.

[Howie]

Strange, the damage looks like pretty hot, but lean usually is accompanied by light colored deposits.  Too narrow to be a valve that wasn't closing.  Seems like too many miles since the work to be poor workmanship.  Maybe something imbedded in the seat? 

[stopintime]

Strange, the damage looks like pretty hot, but lean usually is accompanied by light colored deposits.  Too narrow to be a valve that wasn't closing.  Seems like too many miles since the work to be poor workmanship.  Maybe something imbedded in the seat? 

If the lean condition was for ~ a week - would even that color it whiter?

Engine builder says too long since last adjustment, but it's only 4,000km since it was rebuild.

Nothing to see in the seat - could something have been there for a short while?

[ducpainter]

How long did it run with no compression after the valve burned?

[stopintime]

The gradual problems with difficult cold start and rough idle is a couple of weeks / 1,000km old - as far as I can remember. Clearly much worse the last day before service.

I don't know, but maybe the dark color is deceptive... lean, but camouflaged by the last rough/slow miles with low compression/bad combustion... 

[ducpainter]

<snip>

I don't know, but maybe the dark color is deceptive... lean, but camouflaged by the last rough/slow miles with low compression/bad combustion... 

That's what I'm thinking.

[Howie]

Makes sense.

[Langanobob]

If the lean condition was for ~ a week - would even that color it whiter?

Engine builder says too long since last adjustment, but it's only 4,000km since it was rebuild.

Nothing to see in the seat - could something have been there for a short while?

Maybe I'm missing something but what does the engine builder say about failing to properly install the intake manifolds?  Seems to me it's a clear cut case (if there is such a thing) of running too lean due to intake manifold air leakage causing the exhaust valve to get too hot and eventually burn.  I'd hope the engine builder would make it right.   

[NAKID]

Maybe I'm missing something but what does the engine builder say about failing to properly install the intake manifolds?  Seems to me it's a clear cut case (if there is such a thing) of running too lean due to intake manifold air leakage causing the exhaust valve to get too hot and eventually burn.  I'd hope the engine builder would make it right.   

And by make it right I would ask for them to pay another builder, not do the work themselves. I wouldn't trust them...