88 Turbo II, completely stock throttlebody here.



So I pressure tested my engine with an air compressor and I noticed a ton of air shooting out of this part of the thermowax. I thought I had a split gasket or something.



But then I pulled off the thermowax and it looks like the gasket is supposed to be like that? I have circled where the air is coming out of. I just don't want a vacuum leak messing up my idle and a boost leak killing my power.

Do I need a new gasket or something? Is that a port that was designed to let air into the engine to affect the idle?

 

The thermowax should just have coolant flowing through it to heat up the wax. That should cause it to expand and move the plunger out, against the fast idle cam and bump up the idle.

I know on the NA's air shouldn't pass though it, but turbo's I don't know.

 

it's just weird because it looks like that hole was meant to be there, given the shape of the gasket.

EDIT:



I guess it's supposed to be shaped like this (the little slit on the side)? Supposed to allow air in?!

 

now here is a pic of the n/a thermowax gasket from the parts catalog... doesn't appear to have the slit in it. Can anyone confirm?

 

alright, looking at it some more... if in fact there is supposed to be air entering/escaping from here, it looks like it feeds a little air passage that goes into the throttlebody and feeds the fast idle cam, which I presume has its own set of internal butterfly valves that you can't see. Since the engine is cold, the fast idle cam butterfly valves is open, and air is being sucked in. That's my theory.

 

It doesn't seem like anyone knows for sure. So maybe I will just put some gasket sealer on it and call it a day. that would be a gigantic boost leak...

 

I've not the perfect answer for why there is a slot there. But all it does is go to the area where the throttle shaft End is. If it leaks any air from the throttle body shaft, it would be minimal.

I would install it without the RTV clogging the passage.

 

Just a picture:

 

Thread revival.

Just found this same problem. Does anyone know?

 

It's meant to leak as a failsafe.
Under boost, if any air leaks past the throttle shaft, it would apply boost pressure to the gasket. This area is poorly machined and clamped, and my guess is Mazda ran into problems during testing and the boost leak letting air into the coolant system or greating a coolant leak wasn't worth redesigning the entire complicated assembly, so they added a bleed.
Replace your throttle seals and polish you butterfly shaft and your leak should disappear.

 

Even on an NA? I've got an S5 NA

 

I remember taking those pics on like a Motorola flip phone