I’ve used sodium silicate on three vehicles that had head gasket leaks where the vehicle wasn’t worth the time or money to replace the head gasket(s). And in each case it stopped the head gasket leak. One vehicle has been on the road for over a year with no problems.
You can order a bottle of sodium silicate from a local pharmacy for about $20.00. You can read how sodium silicate works at stopping head gasket leaks here. http://en.wikipedia.org/wiki/Sodium_silicate#Automotive_repair
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