I theory yes, but if the coolant really is the indicated temp, then given
the air and water cooling, I would expect the whole engine to be running
hotter
but this isnt the case is it. Do you have an EGT, it would be interesting to
see if there is any large change in EG temps from climb to cruise if you
didnt alter
mixture or throttle. I would doubt it would be an airlock as this normally
would give you a localised HOT Spot with perhaps one cylinder running hot
(also not the case according to your CHT)
a worn out water pump can give some weird results but unless the impeller is
slipping at certain RPM again you would expect higher temps almost all the
time, unless you are getting enough
air only cooling in cruise flight to overcome low water flow rates.
Excessively high flow rates can also give you high coolant temps as the
water passes through the radiator too fast to be cooled
effectively at low speeds this is normally caused by a jammed or broken
thermostat that controls water flow based on temperature (same as in your
car) if your engine takes longer to warm up
than it used to and then runs hotter I would suspect that, but I dont
believe the 9XX engine use a thermostat, given the low cruise temps (50 deg
C) some are reporting.
I still believe it worth while to try a fluid filled temp gauge with a bulb
you insert into the water line and tube back to the gauge, just to confirm
your water temps are accurate. This will be
quick, easy and cheap to do, you can get one from most auto parts stores for
around $25. That way you know you are correct, and not being tricked into
thinking you have a coolant
problem, when it could be an electrical problem giving you a false reading
to high temps.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Karl Heindl
Sent: Sunday, 27 July 2008 12:03 PM
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Craig,
If it is the timing, would it not also affect the cylinder head
temperature ? I don't know much about engines.
What about a faulty water pump or an airlock.
Karl
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From: craigb@onthenet.com.au
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Date: Sun, 27 Jul 2008 11:26:16 +1000
I am sure the Rotax people would be able to check the timing in a couple
of minutes.
given I havent had a chance to get a really close look at a rotax engine I
couldnt comment on how they set the initial spark timing, If you had access
to
a pully or flywheel that runs at crankshaft speed it would be possible to
create your own timing marks, but it requires you to remove valve covers and
a spark plug so you
can determine when cylinder 1 is at TOP Dead Centre (ie when the fuel air
mix would be burning if the engine was running)mark the pully or flywheel
then coming back the correct number of degrees and creating a mark or
pointer on a fixed part of the engine next to the pully/flywheel. You can
then use an inductive pickup
timing light that will detect the spark pulse running to the plug and
flash a strobe beam in time with the spark. Point the light at your timing
mark with the engine running and you
can see the mark on the pully and the pointer should line up each flash of
the stobe.
As for the engine running fine, it may actually run slightly better that
normal at higher rpm as the advanced spark gives the fuel air mix longer to
burn, too much advance
is a bad thing though as it is much the same as your engine pre-igniting
which can happen with lower rated fuels which can do damage to your engine.
good luck
craig
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Karl Heindl
Sent: Sunday, 27 July 2008 9:46 AM
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Hi Craig,
I am quite sure about the temperature. When it reaches about 120, it
boils over into the overflow bottle,
which is what I would expect. And in the cruise it is normal.
The ignition timing is something new and I wouldn't know how to check
that. The engine is running just fine.
I will fly over to the Rotax agent this coming week and see if he has
any ideas.
Cheers,
Karl
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From: craigb@onthenet.com.au
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Date: Sun, 27 Jul 2008 08:47:25 +1000
Karl, just a thought here, but do you KNOW your temp sender is correct,
IE stuck it in a pot of just boiled water which you can know the
temp of between one or two degrees of error and subjected it to
vibration etc by shaking it etc. When I was racing we had problems from time
to time with faulty sender units that would
vary by as much as 20 deg C. and this variation would change across
minutes or even instantly in some cases. It was a major pain to
work with, when you expect an engine to be running close to max temps,
and then it spikes 20 degrees over max. Might i suggest
you try a fluid filled type sealed unit to run as a comparison so you
can see if there is a difference.
The other thing i would be looking at if you believe the temps are
accurate, is your spark timing, excessively advanced timing will cause high
temps at low RPM. ie warm up
and taxi. but will not be as noticable at higher RPM. I have seen 20 -
30 degree C increase in temps from around 5 degrees of advance from say 10
to 15 degrees BTDC. high
levels of spark timing advance are generally helpfull at higher RPM but
not much benefit at low RPM. Some of the modern bike engines vary spark
timing by as much
as 20 degrees depending on conditions.
hope this helps
craig
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Karl Heindl
Sent: Sunday, 27 July 2008 7:55 AM
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Bob,
I certainly have, plus all the other gaps near the air intake. I
sealed off the gills and opened up the area at the
bottom aft of the radiators for main exit.
Karl
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From: ptag.dev@tiscali.co.uk
To: europa-list@matronics.com
Subject: RE: Europa-List: Coolant overheating
Date: Sat, 26 Jul 2008 22:13:02 +0100
Hi! Karl
Have you blocked the gap between cowl and underside of oil cooler?
Bob H
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Karl Heindl
Sent: 26 July 2008 13:30
To: europa-list@matronics.com
Subject: Europa-List: Coolant overheating
I have been unable to solve my overheating problem:
I had replaced all glycol coolant and all hoses. Ever since then the
coolant temperatures on the ground and in the climb are way ahead of the oil
temperature.
After warming up the engine the coolant is typically 25 C (45 F)
hotter than the oil. The oil and cylinder head temperatures are always
normal. Only in the cruise am I getting normal readings. The coolant temp.
probe is in the coolant and is accurate.
I have run out of ideas. Has anyone got any clue about this mystery ?
Cheers,
Karl
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