Radiator Cap Question
 

My strut bar was hitting the one on then engine while I was at my last drift event.

So I was wondering, can the cap on the rad be switched with the one on the engine?

I take it you have one of the weird S4s with two radiator caps, or an aftermarket radiator? They should all be the same 13 lb. caps.

You may find this helpful:

http://www.nopistons.com/forums/topi...ooling-system/

I have no experience with S4's, but from reading that it seems the cap on the T-Stat area is just a filler cap and not a pressure rated radiator cap. Therefore it may cause problems if switched to the radiator since it will allow the radiator to overflow 24/7.

You may have a pressurized cap (has a spring on it) on the engine side and not the original mazda "cap" (no spring loaded) which may make it bulkier, but nothing wrong with this....

Stock rad. Stock caps.

Yeah my old one went (oem mazda) and they gave me a replacement that was bulkier.

What's the deal with aftermarket caps?

You need either a O.E. cap for the engine side or an aftermarket cap that doesn't have a spring to relief pressure (shouldn't be as tall). I suspect you have the latter right now? I don't think anyone besides mazda and mazda suppliers can give you the proper cap but I haven't looked...

Ok I think I understand. But would switching caps work?

Is there a true radiator cap in both locations? If so yes. If not no.

You can use a radiator cap as a fill cap in a pinch, but not the fill cap as a radiator.

The info is above in my detailed explanation :lol: I quoted it at the bottom here

Alright, I understand now. Guess I'll need to find a way to raise the bar or get a thinner cap.