My friend has been losing coolant. I have found that when he revs the engine to @ 4000 rpms and returns to idles, or guns it on the road, the rad reservoir will empty into the engine, then flow back into the reservoir coming out of the over fill tube. Any fix to this?

 

The extra pressure from the water pump may be expanding the radiator hoses. If so, they are probably old and soft and should be replaced.