Volvo/Autoprop not making rated RPM..advice please


Niels Faerch <nrfaerch@...>
 

We're only getting 2400RPM with wide open throttle. The prop is clean
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-pitched
prop?

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

Thanks


Ag Av8ter
 

Hello Niels,

When we bought our SM she would only turn up 1800 RPM. I hade the
same
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
up
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
with
a can of aerosol carburatur cleaner in the gap between the turbo and
the loosened exhaust piece. Spray bunch of carb cleaner all around
the
turbo, pay special attention to the "fan" and pressure relief valve
and
shaft. Use your finger or soft tool to work the "fan" so that is
moves
easily. The carbon deposits will flush away and you are done. Put
it
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
would
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
WORLD CITIZEN
SM #266



--- In amelyachtowners@yahoogroups.com, "Niels Faerch" <nrfaerch@...>
wrote:

We're only getting 2400RPM with wide open throttle. The prop is
clean
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-
pitched
prop?

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

Thanks


amelliahona <no_reply@...>
 

Hi Niels:

There are a host of reasons why the engine may not make RPM:

1. RESTRICTION IN THE FUEL SUPPLY;
a. Check that the fuel supply valve is completely open, I couldn't make
RPM once and found that an object had fallen against the fuel shut off valve
in the quaterberth companionway and had partially closed it.
b. Partially clogged fuel filter(s), either or both of the on engine fuel
filter or the in line fuel filter.
c. Bad lift pump (more difficult to diagnose)
d. Clogged injectors (diagnose by swapping for new injectors, since it
is wise to have a spare set aboard, expensive though)

2. RESTRICTION IN THE AIR SUPPLY:
a. Turbo blades not turning easily due to:
a1. Coking in the turbine housing or on the turbine blades as discussed
by others.
b1. Coking of lubricating oil in the turbo center housing due to not letting
the turbo cool properly prior to shut down. Either item can cause the turbo to not
spin normally. Remove the exhaust side or the induction air side (whichever is
easiest, reach in and spin the turbo blades by hand. They should spin freely. If not
trouble shoot the cause.
b. Clogged or collapsed air filter.

3. EXCESSIVE LOADING OF THE ENGINE:
a. Dirty Prop (you already verified this isn't the problem).
b. Transmission malfunctioning (I haven't a clue how to trouble shoot this).
c. Dragging shaft brake. (rule out by direct observation).
d. Incorrect prop or prop malfunction. Can you make better RPM in reverse?

Be methodical in trouble shooting. Verify each component and good luck.

Gary Silver, Amel SM 335 with a Yanmar engine.

--- In amelyachtowners@yahoogroups.com, "Niels Faerch" <nrfaerch@...> wrote:

We're only getting 2400RPM with wide open throttle. The prop is clean
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-pitched
prop?

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

Thanks