[DeTomaso] Bleeding the cooling system
MikeLDrew at aol.com
MikeLDrew at aol.com
Thu Apr 4 20:15:03 EDT 2013
In a message dated 4/4/13 7 57 19, kirby.schrader at gmail.com writes:
> With this plate in the block, you can use any thermostat you want in
> place of the Cleveland type.
>
>>>This used to be 'the thing to do', but it's not a popular modification
anymore. Among other things, it creates cavitation, as there is essentially
no water movement in the cooling system until the thermostat opens, so the
water pump just churns and churns away. It also leads to hot spots inside
the engine, as the coolant near the combustion process is heated up, but the
coolant near the thermostat is still too cold to allow the thermostat to
open.
JC Christian took me to school on all of this some time ago and I learned a
lot from him. Among other things, the 'hat' in the Cleveland thermostat
doesn't completely block off the orifice in the block, by design. A certain
amount of flow through the engine (instead of through the radiator) is
always desired. If you look at the other Ford engine familes, i.e. Windsor, or
FE, they have a bypass hose at the thermostat outlet that permanently
routes a certain amount of coolant internally, bypassing the radiator, when the
thermostat is fully open. When the 351C thermostat is closed, there is a
larger amount of water bypassed, and when it closes, it partially blocks the
orifice, and the remaining area is about the same as the area of the bypass
hoses on the other Ford engines.
Also, if you block the thermostat orifice, the block suffers from thermal
shock when the thermostat finally opens. It is incredibly hot in the hot
spots, and then that hot fluid moves forward, and ice-cold fluid from the
radiator takes its place. WHAM! That's really hard on the engine. A
functioning bypass means that the engine warms up uniformly and properly, and when
the thermostat opens, the cold water coming from the radiator mixes with
warm water circulating inside the engine to ease the temperature transitions
until the system stabilizes at a set temperature.
The executive summary to me was: Bypass good. Blocked passage bad.
At least, that was my takeaway from the discussion.
Mike
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