Do any of those cracked block , blown head gaskets ,leaky radiator repair fluids work? If so which works best?

In my opinion, no. Many such products can later prevent fixing the problem properly. My advice is to stay far away from them.

TX is right. There's NO way they'll work for gaskets. The #1 cause of gasket failure is expansion and contraction. So any fix from the bottle will be short lived as soon as the head expands and contracts.

As for fixing a crack in the head--I've never actually seen a "success" story--only heard about them--from the people who sell the stuff.

In my opinion, no. Many such products can later prevent fixing the problem properly. My advice is to stay far away from them.

Thanks.Good advice.

The only thing that will fix a blown head gasket is a new head gasket lol