Radiator advice please

[Crazypierre]

Hi Guys
Hope you're all well and your lovely cars are running nicely.
Wonder if you could help me out?
Problem:

-I can see water leaking from around my radiator cap
-the water in the expansion tank keeps going down.
-When I remove the radiator cap, the water is full in the rad up to the expansion pipe hole
-I removed the expansion pipe from the radiator and when I blew into it, I cannot blow into it or get any air through to the expansion tank. Its as if the pipe is blocked.

Question:
Should I be able to blow into that pipe and hear the air come out into the water in the expansion tank? I think so, given its an expansion tank.
Clearly, water is being drawn from the expansion tank as the level is going down and water is leaking from the top of the rad....

Any ideas?
Could  there be a blockage in the expansion tank or expansion pipe that is allowing water out of the tank but not back in?
 
Thanks
Pete

[mirafioriman]

If you can't blow through the pipe then it does sound as if it is blocked. Try a new rad cap for the leak issue as sometimes the fail and don't hold the correct pressure causing a leak. As they are so cheap I usually fit a new one as part of my first service when I purchase a vehicle.

[Henk]

Get a new cap, it is leaking at the top gasket I assume (or the sealing surface of your fillerneck is damaged)
If  level  is too low because the cap is leaking under pressure with running engine, after stopping the engine,  the (LP) valve in your cap will open because of cooling down of (too much) vapor  and thus creating low pressure in radiator and surge water from expansion tank (this is what it is supposed to do)
Normally you will not be able to open Expansion tank valve just by "lung" pressure (Matt Biondi could  do this maybe..)

[Crazypierre]

Thanks Dave and Henk. I will get a new radiator cap. Where can I get one? Are they specific for Fiat or will any cap work?

[Henk]

not just any cap!
There must be a number stamped in to the cap like 0.9 or 1.0 indicating the HP opening pressure, what I remember...
It should be in the same range

Regards
Henk

[Tas131]

Some radiators have different height filler necks, there are short and long radiator caps, make sure you get the right one.