[Healeys] Thermostat gasket sealant

[Harold Manifold]

Hello,

There's been a comment that the list has been quiet lately and we need a
topic that will generate more discussion. I'd like to suggest Healey
cooling and thermostats as a potential topic.

A general comment about systems with a control valve, which describes a
Healey cooling system: for the system to be controlled by the thermostat,
it should never be 100% open or closed. When fully open or closed, the
thermostat isn't controlling. Ideally, the thermostat would be 50% open
when the engine is fully warmed up on a 70°F day. I've found my 180°
thermostat controls well in the summer, but when the temperature drops
below 60°F, it takes a long time for the thermostat to start opening, and
it likely operates in a narrow portion of its range. It makes sense to
switch to a 160° thermostat for driving in temperatures below 60°F for
extended periods.

There's a bypass in the block that allows water to recirculate without
crossing the thermostat and entering the radiator. This aids faster warm-up
and prevents the water pump from dead-heading when the thermostat is
closed. As others have mentioned, the older bellows-style thermostats had a
sleeve that restricted bypass flow as the thermostat opened. I've been told
the 4-cylinder Healey engines lack this bypass. Blocking the bypass will
slow engine warm-up; the bypass should be restricted once the water reaches
180°.

I'm aware of a couple of options to restrict the bypass. The easiest is to
use a FlowKooler thermostat, which I use. They're high-quality, high-flow
thermostats that partially restrict the bypass when open. The other
practical option is to modify a Land Rover thermostat (Land Rover
Thermostat 596225, for those interested). The sleeve must be cut off the
top so it sits flush in the housing. I used a Dremel to cut the sleeve off
and have pictures if anyone is interested.

You have the correct temperature thermostat when the water temperature
stays within 20°F of the opening temperature under most driving conditions.

Comments are welcome.

Regards,
Harold


On Mon, Feb 17, 2025 at 3:44 AM sbyers--- via Healeys <
healeys at autox.team.net> wrote:

> Since I tried Hylomar, it is all that I use on gaskets (Permatex has an
> equivalent).  It seals well and is non-setting.
>
> For thermostats, I tried the sleeved 160 that Moss offered (apparently no
> one had a sleeved 180) in my BJ8 and found that in the wintertime I had to
> actually block half of the radiator to get the coolant to come up to
> temperature.  Later, I was fortunate to be able to score an original NOS
> sleeved 180 made by AC from Kees Oudersluijs who was active on this list
> and got a couple of spares as insurance.
>
> A thermostat doesn’t really “control” the coolant temperature, but reacts
> to it depending on the coolant flow and temperature of the air through the
> radiator.   Initially, it limits the flow for faster warm-up of the
> engine.  Once it is wide open, it is out of the loop.
>
>
>
> Steve Byers
>
> BJ8 Registry
>
> AHCA Delegate at Large
>
>
>
> *From:* Healeys <healeys-bounces at autox.team.net> *On Behalf Of *Michael
> Oritt
> *Sent:* Sunday, February 16, 2025 7:06 PM
> *To:* Healeys at Autox <healeys at autox.team.net>
> *Subject:* [Healeys] Thermostat gasket sealant
>
>
>
> My 100 will not come up to temperature (at least yet) with a 160
> thermostat.  I am putting in a 180 and wonder what is the preferred gasket
> dressing?
>
>
>
> Best--Michael Oritt
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