k i got an 87 n/a and it's leakin coolant from the filler cap. i found a paste of bondo or somethin patchin up a hole that looks to be the one that, went to the coolant resevoir

...now my question is having this can it cause alot of pressure in the system?

also if i replace the housing should i get one with that tube that runs from the filler cap to the bottle or just get a plastic neck with no cap?

thanks much!

 

S4's have two cooling system caps; a filler cap on the top of the thermostat housing and the pressure relief cap on the radiator. The one on the radiator has the hose than goes to the overflow bottle. I assume you're talking about the cap on the thermostat housing. This does not need a hose. As long as the pressure relief cap on the radiator is working properly the system will be kept at the proper pressure.

 

hmm i do and it seems like theres stll too much and my radiator hose bulges up don't know what it could be i feel the water flowing i've even ran it with no thermostat and it still had alot of pressure im hoping its just a water pump....

 

they are brand new caps even on the themo housing cap. the radiator is hot so is the hose so that means water is moving....my car idles real smooth it doesn't smoke..i change the lines even vac...even put a clutch fan in...

 

What's the cap's pressure rating? It should be 0.9bar or 13psi.

 

13psi

 

hey not to steal this thread but what is the little green connector on the back of the fillerneck(on the water pump)(also s4 modle) for?

 

Your question is a bit ambiguous. On top of the thermostat housing/filler neck is the temp switch for the auxiliary electric fan (if fitted); on the back of the water pump housing is the ECU's coolant thermosensor.