[Healeys] Radiator cap with expansion tank.

[Harold Manifold]

The issue with installing an expansion tank on an Austin Healey is the
difficulty in finding a location under the hood. For an expansion tank to
work properly the neck and cap must be at the highest point in the cooling
system so air can rise to the highest point.

A coolant recovery tank, on the other hand, can be installed at any
elevation which is why I suggested they are more suitable for our Healeys

See the following from Canton who are experts in the field.

Expansion Tank Set Up:
An expansion tank is part of the pressurized section of the coolant system.
An expansion tank can easily be recognized by the neck and cap used. Since
the tank is under pressure it will require a pressure rated cap and neck.
The pressure relief in the expansion tank should be the highest point in
your coolant system.


Harold

On Sat, Oct 11, 2025 at 5:35 PM JSARCH via Healeys <healeys at autox.team.net>
wrote:

> This respones is correct.
>
>
>
> *From:* Healeys <healeys-bounces at autox.team.net> *On Behalf Of *Jim Ryan
> *Sent:* Saturday, October 11, 2025 2:03 PM
> *To:* Simon Lachlan <simon.lachlan at alexarevel.plus.com>
> *Cc:* Healeys <healeys at autox.team.net>
> *Subject:* Re: [Healeys] Radiator cap with expansion tank.
>
>
>
> Hey Simon,
>
>
>
> No, the radiator cap stays on the radiator. Increased pressure in the
> radiator raises the boiling point. If the radiator gets hot enough for the
> pressure to release the cab then the overflow will go into the wall bottle.
> Once it cools down it's supposed to get pulled back into the radiator. Of
> course, this is a British car so theory and reality May differ. But you
> definitely want to leave a lady in the cop on the radiator.
>
>
>
>
>
>
>
> Jim Ryan
>
> ©¿©¬
>
>
>
> On Sat, Oct 11, 2025, 11:45 AM Simon Lachlan via Healeys <
> healeys at autox.team.net> wrote:
>
> Forgive another stupid question but it’s sensible to be sure……….
>
> Am I right in assuming(!) that, if one fits an expansion tank, the
> standard cap is moved from the radiator to the expansion tank and is
> replaced by a blanking(?) cap ie one which has no spring, no means of
> relief etcetc? Seem logical to me but logic has let me down before.
>
> Simon
>
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