Today's Message Index:
----------------------
1. 01:48 AM - Re: Re: loss of compression (Ken Arnold)
2. 05:11 AM - Re: loss of compression (Catz631@aol.com)
3. 05:18 AM - Re: Re: loss of compression (Dave Austin)
4. 05:38 AM - Re: loss of compression (Catz631@aol.com)
5. 08:41 AM - Re: loss of compression (Roger Lee)
6. 03:47 PM - Re: egt probe, wrong location how bad (dave)
Message 1
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| Subject: | Re: loss of compression |
Hey Dash,
About how much would you add?
Ken
do not archive
----- Original Message -----
From: "dashwood" <dashwoodlock@hotmail.com>
Sent: Saturday, August 08, 2009 10:51 PM
Subject: RotaxEngines-List: Re: loss of compression
> <dashwoodlock@hotmail.com>
>
> I may not be understanding your plane but if i had no oil on the dipstick
> i would add some first before hand prop to ensure i didn't just pump air
> into the system from an empty reservoir. ????
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=256720#256720
>
>
>
Message 2
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| Subject: | Re: loss of compression |
Roger,
Thanks for your response! Your discussion makes perfect sense. It had not
even occurred to me that the rings and loss of oil around them might have
caused this. My only thought was a sticking valve as that has happened to me
before on other aircraft.
I will discontinue the use of Marvel also.
After flying the aircraft yesterday my old nemesis came back. On shut down
with the throttle all the way closed (aprox 1400 rpm) the engine stopped
and then turned about 3 or 4 revolutions backward. I restarted the engine and
then shut it down the same way. It did it again! I restarted then increased
the rpm to aprox 2200 then closed the throttle and turned off the mags at
the same time (a method mentioned by another owner) that seemed to work on
this one occasion.
After a little thought I decided I better check for possible air in the
lifters, because of the backward rotation, so I pulled the valve covers and
checked the valve clearances. They were OK.
I have called Lockwood about this and I have decided that I am the only
guy in the country to have this problem. It is much like an old car used to
do when you shut it down and it keeps running. I am also one of two in the
country that has had an oil filter loosen up by itself and almost spin off. I
tightened that Rotax filter absolutely in accordance with Rotax instructions
and torque marked it. I now safety wire the filter in place with a large
clamp (Adel rubber under it)
Back to my engine "run on " I have been using 87 auto fuel as specified
for the 912 UL. Last summer I went to premium when this happened but now
premium is not available without alcohol. I guess I will bite the bullet and use
it. It will all be that way anyway.
I had thought that my engine shut down technique might be the problem but
I guess that octane plays a bigger role in this summer (95) heat.
Thanks again Roger !!
Dick Maddux
Rotax 912 UL
Milton,Fl
Message 3
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| Subject: | Re: loss of compression |
Where is the oil draining to? The outlet from the dry sump goes into the
top of the tank. The outlet from the tank goes from the top of the tank
(with tube to bottom of tank) to the oil cooler/pump inlet, so how is the
tank draining? Do you have it hooked up correctly?
Dave Austin 601HDS - 912
Message 4
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| Subject: | Re: loss of compression |
Dashwood,
My Kitfox sits high on smaller bushwheels. The oil tank is above the
engine and is fixed as low as it will go. The oil siphons back into the engine
case as it sits until it goes below the dip stick (over a few weeks) When I
"burp 'the engine it is all full again. If I were to put more oil in, oh boy
what a mess !!!
I really don't know how far it drains down. I suspect if I lifted the tail
up to where the tail is level I would see some oil on the dipstick. If it
drained all the oil into the crank case I am sure I would have a massive
hydraulic lock (which I haven't)
I have asked this same question on the Kitfox forum many times and no one
has an answer. (they have it too)
My oil filter contaminant and oil analysis checks have all been normal. If
there was any abnormal cam wear I am sure it would show up. I have done the
lifter check many times and it is all normal.
The plane was built in 2002 so has had many years to develop a problem
over this but hasn't so I guess at some point the siphon stops.
Dick
Maddux
Rotax
912UL
Milton,Fl
Message 5
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| Subject: | Re: loss of compression |
Hi Dick,
The way I understand the situation is you are flying shut down to 1400 rpm the
kill the engine while flying and it wants to keep going or kick back some?
If this is true then your problem isn't that strange. You are better off having
that idle set higher like 1650-1750 rpm to have a smoother run on the gearbox.
The 912ULS with more compression do better with 1800rpm.
When flying with a little speed it takes very little with the UL for the wind over
the prop to want to keep it in motion. When it finally gets so slow that the
compression wants to stop it and the wind trying to turn it you can get the
backlash at times. Even on the ground at idle if the engine is so slow and compression
starts to impede the stroke then shut down makes it act strange and
it may try to kick back. Try setting the carbs at 1700-1800 rpm and do a good
balance on them. I bet your issues go away. And while I'm thinking of it when
was the last time you checked the carb float arm height? Supposed to be 10.5mm
from the carb lip to the bottom of the float arm when the carb is setting upside
down. Also make sure the carb vent tubes are in the same area, i.e. in the
Rotax airbox, and if not there, not in a jet stream of air.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=256782#256782
Message 6
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| Subject: | Re: egt probe, wrong location how bad |
Roger Lee wrote:
> Number one reason Rotax engines have issues.....owners.
> If everyone stuck to exactly what Rotax wanted we would have less issues, but
experimentals experiment. I don't think it's always a bad thing so long as you
have a good reason for doing it with full knowledge of the consequences down
the road. I can't say I haven't experimented and taken my lumps, but that was
many years ago. Now I leave the engine alone and experiment on non damaging ideas.
Well Said Roger.
1 5/8" from cylinder post casting on a Kitfox with inverted Y pipe ( not to mention
a hacked one that costs Kitfox 582 driver about 5 to 7 HP
I just went out to shop and looked at several clamp style EGTs one on my 582
and it about the same as a 532 Kitfox as well.
--------
Rotax Dealer, Ontario Canada
http://www.cfisher.com/
Awesome *New Forum *
http://rotaxaircraft.com/forum/
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/profile_videos?user=kitfoxflyer
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=256834#256834
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