When I bought my metric Motor engine, it came with a lot of paper work. one was on gasket removal methods.
Please do not use rotary disc type scotch-bright surface prep pads (IE: Rolex, Whizzer) for removal of gasket material.
these pads, in conjunction with drill or die-grinder
*Will remove block or head material*
Particularly on aluminium, this will creat low areas and an
uneven surface. whicj will likely result in gasket failure.
The prefered method for gasket removal would be to use
a razor blade type scrapper followed by a flat surface
sanding pad (non-rotary type) or sharpening stone.
Per the following article from motor service magazine:
plug drain and supply holes punched in the gasket, inpede heat transfer. make a gasket stick andtear, or soften the gaskets surface enough to cause premature failure. In engine sealing, the mark of an expert is decidedly not a big wad of hardeded silicone squeezed out of every joint, but proper preparation of sealing surfaces.
Metal Mangling
Speaking of surface prep, the use of 3M style abrasive disks for cleaning then is an absolute no-no. Contrary to popular belief, even the new designs with the abrasive encapsulated in plastic are not safe and will destroy an engine.
Clearances are tighter today than ever befor, and even the slightest silicate contamination in the oil will wipe out a set of bearings. Plus, abrasive disks will remove significant amounts of metal. They`ll even do a job on cast iron (if you doubt this, grab an old rotor and your disc cleaning tool and lean into it - the flying sparks show you what`s happening) they are especially bad about removing metal from around holes> creating a concave depression. Use a scraper and chemical gasket removers.
I`ve done forensics on several destroyed engines over the years, engines that had had major work done on them shortly before losing the bottom end. in nearly every case, oil analysi revealed abrasives or contaminants.
An extra half hour of clean-up is a small price to pay compared to buying a customer a complete engine.
Iam just passing this on, take it or leave it, don`t yell at the messenger
Charlie