Yesterday I went out for my $100 hamburger flight. At about 400 ft after
takeoff
I scanned my gauges and found to my horror that my manifold pressure was reading
52 inches! My EGT was rapidly climbing through 1650 degrees (F) and my
CHT and Oil Temps were climbing at about 240 degrees (F). Since I was low and
slow I immediately pulled back the throttle to 29 inches to maintain some climb
performance to pattern altitude, but temps continued to climb. At pattern
altitude I pulled back to about 22 inches which stopped the rise in temps....but
still way too high, and immediately landed . I knew immediately that I had
a stuck turbo wastegate. Upon landing I pulled off the cowlings and sprayed
the wastegate with "Blaster" (a product in the US for unsticking stuck things).
Thought I had it fixed, so went up for another go at it. Same result. Back
down, cowlings off and more spraying, but this time I tried to wiggle the
wastegate
lever with a long screwdriver.......but it was really "stuck". Finally
I whacked it with a big hammer and "pop" it came unstuck. Took it up for a
flight and all seems well.
My questions for the forum are: 1. did I do any damage to the engine running
it at 52" MAP for maybe 30 seconds? If possible, what should I look for and
what
tests or diagnostics should I be doing to determine if I have any damage?
2. Does anyone have any bright ideas on how to determine if their wastegate
is stuck BEFORE they commence takeoff? My normal preflight runup consists of
taking the engine up to 4,000 RPM, checking left and right ignition drops, then
cycling the prop several times. Then, I put the prop (Whirlwind hydraulic)
into max pitch and take the MAP up to 30", which is about the highest power
setting
I can hold back with the brakes. None of these tests are going to show
me if I have a stuck wastegate.
Ideas and comments appreciated. P.S. I used 100 LL avgas for the first 300
hours
but have used 93 mogas for the past 100 hours.
Garry Stout
914 Trigear.
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