[Healeys] cooling problem

[Oudesluys]

Scale build up in the thermostat or lose bits of scale partially 
blokking it or part of the radiator now and again?
Are you using tap water in stead of coolant? Always use coolant (or an 
appropriate mixture) to prevent scale build up.
Thermostats do go wrong once in a while, even brand new ones. Check it 
first.
The radiator may be the problem as that was "cleaned". The question is 
how good a job did the rad shop. My guestimate is not to good and 
perhaps loose bits of scale are circulating. It is neigh impossible to 
clean a radiator without partial dismanteling and cleaning out every 
single tube. It is better to fit a new core with a higher cooling 
capacity. You can never have enough cooling capacity as long as you use 
the proper thermostat (bar polar expeditions).
It could also be that scale has formed in the cilinderhead and is 
partially blocking the water ways. It hardly ever presents to much 
problems in the block.
Back flushing with a water hose will not help much. You at least  have 
to use caustic soda at high temperatures. Better to have the head 
cleaned ultrasonicly after you have chisseled away as much scale as you 
can get at.
Kees Oudesluijs
NL

Mirek Sharp schreef:
> - it has been doing it for 35 years.
>
> However, the irregular running temp is getting worse.  Yesterday, driving on a
> cool morning, the temp settled in at around 170, but inexplicably dropped to
> around 120, where it stayed for the rest of the 2 hour trip.  I can only think
> the thermostat is sticking open, but why would it function intermittently?
> Also, the thermostat is only  a few years old and I do not drive the car
> regularly.  I plan to pull the thermostat and test it, but thought I would
> plumb the depth of knowledge on the list first.  I have no other explanation.
> Suggestions?