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Message
My coolant
temperature has been rising little by little over the 440 hours I have
been flying my 13B. Last summer on the way to Arlington fly-in, I departed St
George Utah at 100 degrees OAT and the coolant temp quickly rose to 230, my
absolute maximum allowable. I could not climb above pattern altitude, so I
landed. I cobbled together a water dribble system out of drip irrigation
tubing, and it allowed me to continue the trip. After returning home I decided
something had to be done. After checking everything I could think of, I removed
the radiator, and after careful inspection, I found debris clogging much of
the core that was visible. Some of it was bits of silicone used to help seal the
couplings, and some of it looked like scale from the water jackets.I cleaned out
as much as I could get to, and I made a screen out of stainless mesh and
inserted in line inside one of the 1 1/2" silicone hose couplings. I flew it
like that for about 10 hours while I had a new radiator made by Griffin
Radiator. Coolant temps were better, but still not acceptable. I got the
new radiator installed yesterday, and I found the screen already 3/4 clogged
with more scale debris.
Today I flew it with
the new radiator, and at OAT of about 65 F a full power climb out at 80
KIAS resulted in the coolant temp stabilizing at 167 F. I am not running a
thermostat, and part throttle cruise coolant temp was about 130F. Descending out
of 10000 ft the coolant temp dropped to about 110F, and my cabin heat was
practically nil. Looks like I need cowl flaps now! I am actually looking forward
to some 100 degree days this summer to see how it cools now. If a 35 degree rise
in OAT results in the same rise in coolant temp, I predict that my max coolant
temp will not go above 202 F.
My coolant temp rise
problem has been so gradual, while other things were being changed around, that
the possibility of a clogged radiator did not even cross my
mind.
Lessons learned: 1.
Keep good flight data and refer to if often, the only way to catch gradual
trends.
3. 230 F does not
seem to have hurt my 13B, I have probably 10 total hours flying at that
temp.
Keep the shiny side
up!
Chuck
Dunlap
N616RV
13B
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