what is a coolant seal?is it a apex seal...

 

No. The apex seals are at the end of each of the corners of the "triangle" or rotor.

I think the coolant seals are on the rotor housings. Between them. I might be wrong. Hopefully someone with a better description will chime in.

 

They are o-rings that keep coolant from getting into the compbustion chamber or outside of the engine. If you overheat your engine you will probably need new ones.