Ok. lil back story.. i bought the FC from zerox7. loving the car runs great..

this morning i woke up to go to work, and before i head off i always warm up the beast and pop the hood to check oil and listen for anything out of the ordinary.

everything was fine and dandy until i noticed this.. ..

Zerox7 you said you fixed this!!!! LOL

what is? why is it leaking? and how the F*ck to i fix it. i know it flows coolant to the engine soo i am assuming it can be a potential big problem

 

I used to have the same problem. Depending on your fabrication skills or how much you want to spend. You can either make a block off plate(i did this) or you can spend around $65 on the part to replace it.

 

Das ist thermostat housing with an attempted quick-fix that is now leaking. If I remember correctly, there's an o-ring between the cap housing (usually plastic, top part) and the thermostat housing (aluminum, bottom). However, those two bolts love to break off, so be careful and use common sense. I see some coolant above the seal, meaning the cap could be leaking as well, but I'm unable to see if that's still the original cap, or what kind it is. Pop it off first and ensure that it's not the problem here, otherwise replace the o-ring underneath the cap's housing.

 

It could be the o-ring but is likely that seeing someone took the fitting for the cap off that the fitting is cracked like mine was. Either way you will need an o-ring.

 

Looks like RTV was used in place of the O-ring.

 

+1.

There shouldn't be any RTV on there. It gets an o-ring underneath. You can order it through Mazdatrix or a dealership.

 

ok. so it sounds like a simple fix then? and what the hell is RTV?

 

Room-Temperature-Vulcanizing (RTV) Silicone.

 

so im basically... taking them 2 bolts off. popping in o-ring.. and putting it back on? should i use silicone too?

 

The o-ring is Mazda part no. N326-15-174, $1.87 through mazdamotorsports.com. Or just find one that fits.

 

haha i did it ghetto. it worked fine for a long time,(no perminant fix lol) the oring was going bad, it would drip 1 drop like every week.

just go to mazdatrix and buy the O-RING.

and its not a big deal. just 2 size 10 bolt screws, get the oring, and thats it.

i cant go there my self because of issues between me and some of the workers at mazdatrix.

 

.

 

Actually he needs he one without the overflow hose.



When I bought mine i forgot the o-ring, so i just cut a gasket out of gasket paper and its been fine since (I checked to make sure it wasn't tearing it away from the inside, its fine)

 

he should get the one without the overflow tube. if the car is 87 like his signature says, that means s4's dont have the overflow tube there. its on the radiator cap thing.

arent s5's the ones with the overflow tube at the filler cap and not the radiator cap?

make sure that cap is actually sealing. i was using the wrong cap one time and i kept loosing coolant and i had no idea why. stupid me

*edit: ^^ beat me to it

 

Remove the 2 10mm bolts. Scrape whats left of the old o-ring off. Put in new o-ring. Replace/ tighten 10mm bolts.

 

That is an aftermarket piece; you can't use that with the stock radiator. You'd need an aftermarket radiator that has another overflow tube & cap on it.

S5s have the filler neck / radiator cap / overflow tube on the radiator, near the battery.

S4s have the cap and overflow tube on the thermostat cover, just like in the OPs pictures. There's a rubber hose that connects to the opening; It was probably taken off for the picture. However, it it is missing, a new hose needs to be run from there to the overflow tank.

 

i had one like the OP's picture though. It had some sort of thing for a hose but it was blocked off. i never understood why it was like that but i didnt question it. i dont know if the new one i got from the mazda dealership has something like that but i'll check.

 

It's a series 4 NA.

NA S4's do NOT have "the cap and overflow tube on the thermostat cover"

 

Uh I have a nearly bone stock S4 and it definitely has tube that goes to the overflow tank there so RotaryRocket88 isn't wrong.

 

Maybe somebody else had this problem and replaced the cap with the one you now have. I've never seen an S4 with the overflow tube on the thermostat housing. Did you get it fixed up, Bunta?

 

Unless the old white lady was secretly drifting the night away tuning the **** out of my car, then no.
<a href="http://smg.photobucket.com/albums/v355/xIJTIx/?action=view&current=rad.jpg" target="_blank"><img src="http://img.photobucket.com/albums/v355/xIJTIx/rad.jpg" border="0" alt="rad"></a>

 

My NA S4 looked exactly like JxT's. When I put the koyo radiator in I had to get rid of the over flow line coming from the thermostat housing, so I went next door to rotorsport (rotory shop in Santa Clara I work next to) and they had one laying around for me to put on.

 

just go on mazdatrix and get the aluminum replacement its like 30 bucks and comes with the cap and o ring, and it'll never crack either.

 

Really? Then why have all four of my S4 engines had the overflow nipple on the thermostat cover? I guess a bunch of people from all over the world got together and conspired to change them, huh?

Clearly there were two different forms, though before this thread I'd never seen an S4 WITHOUT the overflow nipple on the thermostat cover. The only explanation I can come up with is that different factories in Japan used different radiators/overflow nipple setups. Check your VIN for where your car was made, and there will probably be a pattern. All I know is, the OP had better have an overflow hose connected underneath a radiator cap SOMEWHERE; be it on a stock radiator or an aftermarket one.

 

not at all. i got it as is from Zerox7, i mean i do have an over flow tube to the over dohiky near my radiator cap. does that count?