Ok I have to replace some riser gaskets as stated in a previous post. I think that I am just going to blast the risers to get all of the old gasket and crap off because it will only take a few seconds.
The prob is as most people know when you sandblast, that chit goes everywhere and I am concerned about grains of sand swimming around in my engines cooling system later on.
Should I blast them or just scrape the old chit off?

Lets here some opinions

It depends on what type risers you have. With the stock merc I have had the stainless steel and the cast iron. With the stainless I use the wire brush on the grinder to clean the mating surface. With the cast iron one I throw them away and buy new ones.

The way I look at the cast iron ones you can not change them too often. Is it better to change the risers today or your engine and the risers tomorrow. Old risers can be like a time bomb for your engine. Water dripping on your exhaust valves can ruin your whole day. If your risers show corrosion you might want to check your exhaust manifolds.

I hate loosing engines from leaky risers, riser gaskets or exhaust manifolds.

Good Luck

FlyFast.. They are cast risers and they apear to be in good condition always freshwater, do you think that I still should buy new

I blasted mine without problems....I figured malority of the sand material would be gotten out with the air compressor after youre done. If theres any left in there it realy wouldnt be any different then what little sediment is floating around in the water right now anyway so why worry about it!
And what about the times when you get into shallow areas? YOu have a higher concentration of sand going through the engine then you will have doing this. I say dont worry about it. Just make sure the gasket surfaces are clean for re-assembly.