Pressure cap on the swirl tank

[Mr Clifford]

Dear wise ones, what is its purpose please ?
Why a pressure cap and not a `fixed` one /
Cheers
adrian

[spivvy]

oh no lets wait for the debate

mine pressure cap is not on the swirl pot and it works fine

Edited by spivvy on Wednesday 26th September 19:53

[GreenV8S]

Mr Clifford said:

Dear wise ones, what is its purpose please ?
Why a pressure cap and not a `fixed` one /
Cheers
adrian

Oh no not this one again!

[pies]

worms i see worms everywhere, somebodies opened the tin.Quick somebody get them all back in and maybe nobody noticed

[Barkychoc]

Mr Clifford said:

Dear wise ones, what is its purpose please ?
Why a pressure cap and not a `fixed` one /
Cheers
adrian

Water expands when it gets warm - a fixed cap = KABOOM!

The pressure cap is a bit unusual in that it has a second rubber ring inside the top in the TVR installation, the idea is that the water expands and the excess is allowed to flow into the expansion tank past the pressure seal, when it cools it is supposed to draw it back into the water system.
This doesn't always happen.
If your rubber seal in the top of the pressure cap is leaking (or not there - mine is a bit of bike inner tube - in a normal car installation you don't need this rubber seal so many pressure caps come without it) then it will suck air back in instead of water.

Secondly your pressure cap needs a valve in it to allow the water to flow back in - I don't know whether they all have this or not.

Of course if you are losing water elsewhere aswell (I am, dodgy hose) you've got no chance!

[Mr Clifford]

Barkychoc said:

Mr Clifford said:

Dear wise ones, what is its purpose please ?
Why a pressure cap and not a `fixed` one /
Cheers
adrian

Water expands when it gets warm - a fixed cap = KABOOM!

The pressure cap is a bit unusual in that it has a second rubber ring inside the top in the TVR installation, the idea is that the water expands and the excess is allowed to flow into the expansion tank past the pressure seal, when it cools it is supposed to draw it back into the water system.
This doesn't always happen.
If your rubber seal in the top of the pressure cap is leaking (or not there - mine is a bit of bike inner tube - in a normal car installation you don't need this rubber seal so many pressure caps come without it) then it will suck air back in instead of water.

Secondly your pressure cap needs a valve in it to allow the water to flow back in - I don't know whether they all have this or not.

Of course if you are losing water elsewhere aswell (I am, dodgy hose) you've got no chance!

sorry to ask !
Just wondered thats all

[Mr Clifford]

Thinking about going wild and buying a new cap ! Exciting stuff eh !! (need to get out more)
Do you think this is the one ? --> http://www.nfauto.co.uk/header_tanks.htm

Cheers, Adrian

[Barkychoc]

I got a new one from Halfords - apart from the rubber seal missing inside the top it is fine.
Bought one for a Rover SD1 V8.

No idea if there is a rubber seal inside the top of the one you are looking at there.

Chris

Edited by Barkychoc on Thursday 27th September 16:25

[Gentleman Geoff]

I think we're learning about cooling systems over the next couple of weeks at my college course. Sounds like I'll need to pay attention...

[tubbystu]

Gentleman Geoff said:

I think we're learning about cooling systems over the next couple of weeks at my college course. Sounds like I'll need to pay attention...

Not when it involves the beloved TVR S series. A law unto themselves,








...................thankfully