If it were my car I might do the 603 test for cracks in the head. Even though it is not a 603.That is next morning after use and sitting for eight hours check the rad hose for still being pressurized. If it was I might again consider a waterglass treatment.

It will also coat the internal passages of the water jackets. The reason I might try this approach as I see it as a nothing to loose scenario..If it seals the head crack or cracks you may be okay.

If not you will need another head as they are basically unrepairable. I have always been concerned about any loss of heat transfer as the stuff seems to coat all the waterjacket passages as well on the engines. At least on the ones I have taken apart that have had it done at some point in their lives.

Then again it is hard to say how much waterglass was used. I wanted to deal with this area eons ago for all the cracked 603 heads that. were occurring. What stopped me was that it was a matter of judgement .

I did not want to see people pouring it into their systems when they should not be. Part of my concern was the possibility of reduction of thermal transfer. The cooling systems on these cars do not seem to have a lot of reserve capacity.

Waterglass evolved a long time ago as a leaky boiler repair substance that I suspect is silica based. The high heat of combustion seems to really fuse the stuff in cracks. You could even order the stuff through your friendly drug store and it may still be able to.. Was cheaper that way to get a usable quantity.