Exhaust Manifold and Riser Cleaning

[MadMallard]

I have just removed my engine (1974 Merc 888 - Ford 302 V8) to rebuild the motor mounts and clean paint the bilge. While it is out I plan on taking the exhaust manifolds off and cleaning them. The risers were taken off before the engine came out - some rust inside but plenty of meat left on the walls and passages appear clear (ran water through them). My question is what is the best product to soak/clean these with : CLR, Concentrated Rad Cleaner, or strong Caustic solution??? The engine is in good shape and I really don't know if these exhaust parts are original or not. Prior to my purchase the boat had only ever seen freshwater use. Any feed back would be appreciated.

[TerryKing]

Try electrolytic cleaning. It's a lot safer than fooling around with that acid, it's cheap, and best of all you don't have to scrub.

http://www3.telus.net/public/aschoep...lyticrust.html
http://www.bhi.co.uk/hints/rust.htm

[MadMallard]

By electrolytic cleaning do you mean using a product such as CLR? I was thinking about sandblasting. Any thoughts?