Good evening all, I am hoping to pick your collective brains for a minute. I am having a recurring issue with coolant leakage from the lower intake manifold. Car is a 1988 TurboII, but it's worth noting that the car was put together as a project before I got it. As you can see from the pictures, my housings have coolant holes in the same places, as noted by my fingers pointing them out. However, my lower intake manifold only has 1 hole, which feeds thru it to the turbo feed. Anyone have thoughts as to what would make these different? perhaps the intake is s5? I am just trying to figure this out. Thanks in advance.

 

Also worth noting, the picture is deceiving, the metal where the hole "should be" only looks that way, as I am currently sanding it to remove debris from the old gasket

 

The holes in the engine rotor housings are coolant passages.

The hole in the lower intake manifold is a coolant passage to supply the turbo with coolant.

You use a lower intake manifold gasket and two O-rings to seal the coolant passages on the rotor housings to the lower intake manifold.

What makes them different?
Mazda only needed to use one coolant passage to the turbo and they chose one.

 

Make sure to get the specific o-rings to seal the intake coolant passages to the block. They are thicker than regular o-rings and swell to fit the orifice once used. Make absolutely sure its cleaned out or it'll start leaking again. You can use RTV to help the o-rings seal if the area is pitted or overly corroded.