The car is a S4 NA. It leaks coolant from the o-ring at thermostat housing where it meets the radiator cap/housing. I replaced the cap, o-ring, and the cap housing but it still leaks. I tried to clean the area where the o-ring sits but still leaks. Has anybody had this problem before?

 

Are you trying to use an S5 thermostat rubber o-ring? The S4 thermostat uses a flat gasket, not a rubber o-ring.

This may sound stupid, but did you make sure the wire loom holder isn't sandwiched between the thermostat cover and the housing? I once bought a car in which the previous owner did that.

 

Also RTV silicon is helpful to make sure you don't have leaks.

 

Evil Aviator, no its the o-ring that goes under the rad cap.

Derekcat, I thought about using that but why would it need it if there was an o-ring.

Here's the link where i bought: http://www.mazdatrix.com/b8.htm

I bought part numbers: 15-17YA-N326 and 15-1740-N326

 

Did you put the o-ring (15-1740-N326) between the cap and the filler body, or between the filler body and the filler neck?

 

I put it between the filler body and filler neck.

 

Maybe you over-torqued the bolts and cracked the housing, or under-torqued the bolts and it is leaking?

Other than that, I have no idea because I have never heard of this problem. Maybe one of the mechanics on the forum can help?

 

Yeah the old one was cracked which i why i bought a new one. Ima try your idea of RTV then go from there.

 

Used hi temp rtv and that bitch still leaks so now ima try to match the filler body to a chevy thermostat gasket and see if that helps.

 

I had this problem once.. I was told to use the O-ring AND RTV by a rotary shop. I did just that and it leaked a little.

So I redid it, this time only using a small amount of RTV along with the and it worked perfect! Turns out I just put too much RTV and was too sloppy with it.

 

oh ok. Well i just used the o-ring and made my own gasket from rubberized fiber and thermostat sealant but if that doesn't work then i'll redo it your way.

 

oops, I actually misread your original post. [Thought you meant the thermostat-waterpump housing]
Though same advice.. Ala funkjaw

 

if the cap and o ring are new, then you need to look at the sealing surface of the thermostat cover, is it flat? corroded?

the last one i did i used a little silicon too, but you shouldn't need to

 

The gasket i made and rtv are leaking so i said **** it. Ima buy a godspeed s5 radiator that way i can delete the cap on the filler neck.

 

^ There ya go.