[TR] One last question NOW Restrictor flow

[Randall]

> Reading with interest all this about restricting the bypass 
> hose.  What was
> the purpose of this bypass and why didn't it work?

Just to amplify a bit on what Geo already said, the bypass is quite
important and I do not recommend that anyone run with it totally blocked;
unless you make other provisions for allowing coolant to move through the
cylinder head while the thermostat is closed.  

Cast iron is surprisingly brittle and does not like sudden temperature
changes.  With the thermostat closed and the bypass blocked, the part of the
head near the combustion chamber and valves will get heated to nearly
boiling before the water at the thermostat gets hot enough for the tstat to
open.  Then when it starts to open, it gets the extremely hot water from the
head and snaps full open, allowing the essentially room temperature water in
the bottom of the radiator to be forced into the block and head, suddenly
cooling the head.  The result can be a cracked head.

While experimenting with blocking the bypass (so I could assess the
difference in cooling), I also drilled a hole through the thermostat so it
could not fully block the flow, thereby avoiding the above scenario.  The
result is slower warm up, but that is not a significant issue where I live
(and I don't even have a heater).

-- Randall