So today I found my coolant leak. The water pump housing is cracked can you use a s5 housing on a s4 or should I just go back to a s4 housing. Besides going with Atkins rotary for a new one does anyone have any suggestions?

 

the s5 has the plastic thermostat neck.You can get an aluminum aftermarket neck(rotary13b1) but the S4 housing with the aluminum neck is always a good old part to have handy.
I may be wrong on this but I am thinking about the OMP position too.
Your Housing may not fit if you interchange with another series.

 

IIRC, if you have an s5 housing you need an s5 water pump and if s4 housing an s4 pump...

Here's a quick google search yield:

https://www.rx7club.com/2nd-generati...arched-892888/