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We've gotten way beyond the topic here but there seem to be several issues that probably should be considered together.
1. Aluminum alloys are more active than steel, so in galvanic corrosion the aluminum will corrode, protecting the steel.
2. If the electrolyte is sufficiently oxidizing, the aluminum surface may be passivated which will
protect it but NOT steel. Remember when the old Ford V8 60 HP engine used aluminum heads and studs
rather than headbolts? They usually had to remove the heads with a cold chisel, until someone invented
a thinwall tubular hole saw that would fit over the head studs. (For those who can't remember, the V8 60 dates from about 1935-38 or so.)
3. Although the engine is different, there are sufficient similarities to the earlier engines (B18,B20 and B30)
with which I am a lot more familiar. On those I ALWAYS use a paper gasket, even if I have to make it myself.
The green rigid fibreboard file folders are excellent material for this purpose.
I put a thin layer of grease on both sides of the gasket and on both ends of the rubber rings that seal against
the bottom surface of the head. This extrudes into the pores of the paper and also lubes the surface so you don't
cramp either the gasket or the rings as you force the pump into place before tightening the bolts.
If the gasket seals right, the bolts stay dry. I clean the holes and put a bit of grease on the threads to help this.
I haven't had leaky gaskets or rings or rusty bolts since I started doing this.
--
George Downs, Bartlesville, Heart of the USA!
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