Hi!

I recently noticed that my Turbo S4 was leaking coolant while cooling down (not while engine was on, as far as I could see). I'm pretty sure I found the leak since I found a hose from the cooler "Filler Cap" leading to nothing at all... So, I got a new hose but today as I was about to replace the supposedly broken hose I just could not find "the other end" of it.

At the (very bad) photo I've marked (1) the radiator cap. This one has a hose leading to (2) "Radiator subtank". The supposedly broken hose start at (3) the Filler Cap and dissapeared somewhere under the air filter box.

My emediate guess was that the broken hose (3) should go to the radiator subtank/coolant reservoir (2) but there's no broken hose from that end.

Where should the hose starting at the filler cap (3) go? Or should it just be hangning freely, dumping overflow coolant down the enginebay... seems really weird to me.

Thanks in advance.

Here's the image:

 

uhm, i think you're confusing yourself w/ a TSB or whatever update. Some of the s4's got an updated coolant cap. Which is the reason for two.

But I think that you should only have a hose from your proper cap/nipple to #2, and then #2 dumps a hose to no where.

The overflow tank (#2) will spit out coolant onto the ground if its tank is filled up


Hopefully someone more familiar w/ the TSB updated cooling systems can help you. I never did much work on my base FC that had this. Don't remember the routing.

 

#1 should lead to #2, that is your overflow system. someone obviously put the wrong filler housing on #3 which has the overflow tube in it, some models had a pressure cap up there and that is where the overflow came from (#1 in your system). there should be no nipple on the filler housing #3 or it should be blocked, sometimes it appeared cut off and sealed from the factory as it is a simple mould they made both styles from.

did you or anyone else replace the filler housing recently (#3)? because it sounds like you have the incorrect one on your car.

 

That's what I guessed and that's the way it's routed now, except for the "extra tubing".

I haven't replaced it but I don't know about any previous owner. It sure seems like something is not quite as it should be, though :/

 

Oh... I just noticed that both Haynes Repair Manual and the FSM for NA show pictures with a hose from #3 to #2, but not even a cap at location #1. The FSM supplement for Turbo/ABS shows pictures with caps in both locations but only a hose from #1 to #2, no tube from #3.

It seems as if I have a complete Turbo overflow system and a NA filler cap housing with a loose hose. I'm confused... Should I just plug #3?

 

nope, they used both styles of system in both n/a and turbo models. the style of system seems to be almost completely dependent to the location of where the cars were built.

you can cap #3 or replace it with the proper filler housing.