quick question, I checked mazdatrix and all 86-95 rx7's use the same water pump housing to engine gasket.
So, is it safe to assume that there will be no issues with putting my 87 n/a water pump housing on an s5 j-spec, to retain the coolant fill on the t-stat housing?

 

Right, I used mine and it fits just fine.

 

Your NA water pump housing does not have the fitting for the coolant return from the turbo.
Are you going to drill-n-tap for this?

Also there might be a problem with the water pump housing not clearing the front oil cover - it's either S4 doesn't fit on S5, or vice versa.


-Ted

 

For the coolant return, on my n/a waterpump housing there is a nipple, what would that be used for on the turbo engine?

and last question, If the n/a wp housing thing doesn't work out, will I need s5 or custom radiator hoses to fit my Koyo (made for a 86-88) or will the s4 ones (which are brand spankin' new) work?

appreciate the help guys, I would like to avoid any surprises while doing this swap. I've got all the big stuff covered, but you know how the little things always bite you in the ***!!!