To begin with, valve burning in a diesel engine is EXTREMELY rare. Since in a diesel you are only drawing fresh air, not a fuel/air mixture.

In a gasoline engine, a vacuum leak near an intake valve can lean out that cylinder only causing valve burning. In the described case, we are talking about BLOCKING the EGR, thus not introducing such a leak.

What is the difference between fresh air through the air filter vs. fresh air through a vacuum leak? The only difference is that one will possibly have dirt introduced into the engine.

I think that this tech that is saying this is a gas engine guy and like many people who don't understand the diesel engine, incorrectly tries to transpose gas engine theory into the diesel world.

Just remember almost all the theories involved with diesels are backwards as compared to a gas engine.

Merry Christmas,