Hissing 172

[texastornado]

My expansion tank hisses when engine warmed up.
Anyone had this?
Does the cap need replacing or is this something more ominous?

 

[1812lsd]

I would replace the cap first and see if it still hisses, then go from there.

 

[texastornado]

Yep, cheapest n logical, that's bout where I'd got to.
Had this happen on my cossie n it was head gasket, really hope these aren't the same cos that'll b the end of my 172, can't afford that

 

[dan112]

Yep, cheapest n logical, that's bout where I'd got to.
Had this happen on my cossie n it was head gasket, really hope these aren't the same cos that'll b the end of my 172, can't afford that

It is unlikely to be the head gasket from what I've read previously it is almost unheard of for a head gasket to fail on the f4r engine

 

[texastornado]

:smile::smile::smile:Well that gives me some hope then. New cap n see where I am then..
Thanks

 

[texastornado]

I would replace the cap first and see if it still hisses, then go from there.

OK so cap replaced and hissing gone....... happy days