Steve writes:
>I'm going the overhaul the engine and box on my Mini and would
>like to paint them before they go back in the car. The engine's
>not that greasy but I'd like to remove the old paint first (what
>there is of it). I'm sure I've read somewhere that you can use a
>caustic solution, like you might use to unblock a drain, is this
>to be recommended? The head and block are cast iron and the 'box
>casing is aluminium. Do I need to etch prime the 'box casing
>before painting?
I use some weird chemical brew for cleaning engine blocks, it's sold by a
UK firm called 'Chemsearch' under their brand name of 'Carb-Free'. I get a
similar substance from another UK company at about half the price. It is
expensive, but absolutely brilliant. You can drop in a set of pistons and
rods straight out of an old engine, and the following day they come out as
clean as new ones! I built my dip tank to hold a Triumph 6-cyl engine
complete or a gearbox, and all the parts come out with all traces of old
oil, carbon, paint etc. removed. It's important to paint the *inside* of
the block with an oil-resistant paint afterwards, otherwise the rough
casting holds onto about half a gallon of oil instead of returning it to
the sump!
You can use causic soda (best heated to about 40 degrees C), in fact many
engine rebuilders I know of swear by it, but you can't clean aluminium this
way, the caustic eats the aluminium!
The gearbox on a Mini never was primed in manufacture, but a coat of zinc
chromate would help the paint to stick on! (never painted mine, but then
they were always hidden behind a sump guard and covered in mud anyway!)
Richard Smith
R.G. Smith Automobile Engineering - Triumph & Alvis specialist
- British Parts for British cars
Tel: 0729 823051; Fax: 0729 824092
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