Re: Volvo/Autoprop not making rated RPM..advice please

Ag Av8ter

Hello Niels,

When we bought our SM she would only turn up 1800 RPM. I hade the
questions as you. The solution was easy once I learned how to "fix"
and "maintain" the turbo.

I removed the turbo from the engine for and soaked the hot side in a
bath of break fluid. This softend up the carbon deposits and freed
the "fan". Be careful of the shaft that controls the pressure relief
valve. Reinstall and your engine should turn up. My TMD22P is
supposed to turn up to 4100 RPM, but it never did get above 3850 RPM.
Then I tried a short cut, and this is what I would try first if I
were you. Be sure the engine and turbo are cold (very important),
remove the four nuts that hold the exhaust to the turbo. SLide the
exhaust piece just enough to allow the little red tube that comes
a can of aerosol carburatur cleaner in the gap between the turbo and
the loosened exhaust piece. Spray bunch of carb cleaner all around
turbo, pay special attention to the "fan" and pressure relief valve
shaft. Use your finger or soft tool to work the "fan" so that is
easily. The carbon deposits will flush away and you are done. Put
all back together and run the engine. You should have your RPM back
until next time. There will be a next time. I believe that the
autoprop is way overpitched at the RPM's we use for speed vs fuel
economy. This causes the richness and the carbon to deposit on the
turbo. If you were to run your engine near wide open, your turbo
not "coke up", but you would not gain much speed and you would have
enough fuel to go about half way to where ever you wanted to go. Good
luck, I hope this helps.

Tony Gray
SM #266

--- In, "Niels Faerch" <nrfaerch@...>

We're only getting 2400RPM with wide open throttle. The prop is
as is the underbody. This means we are only capable of developing
around +/- 60% of rated power say around 50-ish HP.

Is is everyone accepting this or are you getting your props re-

Would I be better off changing to a regular adjustable pitch
feathering prop?


Join to automatically receive all group messages.