After removing the head of my 1987 M102 I noticed it has a fair bit of corrosion in the 2" long channels that carry the coolant.

About 1/2 of thechannels are decayed to a depth of around 1/8 to 1/4" (particularly badaround the smallest holes).
It doesn't appear to do any harm as the aluminium is fairly thick in this area.

Two questions -
1. Is this common on Mercedes head that has had a full dealer service history and done 110k miles (I bought it off
the P.O. 4 years ago and the coolant was the correct Mercedes type back then).

2. With regular 2 year coolant changes will the decay in the Aluminium get any worse ?

3. The Head gasket holes matche the coolant holes in the block but not the larger coolant channels in the head. I assume this is normal ?

Doug McCutchan