Mercedes-Benz GL V8 4.6L Turbo engine diagnostics and repair due to misfire on one of the cylinders. We did pressure test and had low compression in the cylinder number six. Also, we did a leak test and found that is it leaking into exhaust so that tells us that there is problem in the head.

We had to remove the head to get to exhaust valve that was leaking. Valve seat on the exhaust valve was damaged most likely due to something flying into cylinder. Whatever got into the cylinder got pinched by exhaust valve and damaged the valve seat. We had to replace the valve and valve seat in order to restore compression on cylinder number six.

In conclusion, in the process of diagnostics we spotted interesting thing. The turbo fin was damaged which leads us to believe that something flew in to the turbo. It’s a strong possibility that the piece of the turbo fin was the object that damaged the valve seat, but still a mystery what actually flew into trouble.