Earl, my understanding is slightly different from yours. When the coolant
is cold, the sleeve is down and the bypass passage to the head is open. The
thermostat itself is also closed and the coolant does not enter the
radiator, but circulates back to the head through the bypass. As the
coolant heats up and the thermostat opens, the sleeve rises and blocks the
bypass to the head. When the thermostat is fully open and the sleeve is
fully up, the bypass is blocked and all of the coolant now has to go through
the radiator. In other words, the purpose of the sleeve is not to speed up
the warm-up (which is the function of the thermostat itself), but to block
the bypass when the coolant is up to running temperature.
As alert listers will remember, last summer I reported problems with keeping
my engine cool in spite of all kinds of approaches to cool it down. I
bought a 190-deg. sleeved thermostat (AC NOS, made in UK) from lister Kees
Oudesluys. This did have the effect of lowering engine running
temperatures, but not as much as I had hoped. It was only when I had my
stock radiator re-cored with a modern core with larger capacity that my
problem was solved for good. My BJ8 now stabilizes at 190-deg. in hot
weather, even when stuck in traffic, which is what I think it should do.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at
autox.team.net]
On Behalf Of Earl Kagna
Sent: Sunday, May 22, 2011 4:17 PM
To: Schneider Mark; healeys at autox.team.net
Subject: Re: [Healeys] BJ8 Cooling System
Mark:
You're close. As I understand it, the bypass function on the engine is
designed to block (mostly) the bypass hole to the head with the sleeve on
the thermostat in order to speed up the warm-up. This is what I learned
when experimenting with sleeving regular thermostats years ago. I
understand that reproductions of the original Smiths (sleeved) thermostat
are now available, but I have not checked.
In other words, it's no big deal to run a current (cheap) thermostat - we've
all been doing it for a long time.
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