Today's Message Index:
----------------------
1. 04:04 AM - Re: Engine Vibration (Penco)
2. 06:06 AM - Re: Re: Engine Vibration (A. Dennis Savarese)
3. 06:22 AM - Re: Engine Vibration (Penco)
4. 06:27 AM - Re: Re: Engine Vibration (George Coy)
5. 06:45 AM - Re: Re: Engine Vibration (A. Dennis Savarese)
6. 09:41 PM - Brake Pressure (Jon Boede)
Message 1
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| Subject: | Re: Engine Vibration |
Hello guys, I'm reviving this topic because I'm coming short of an explanantion.
Bit of history :
Bought the aircraft last year. It worked fine and then, some 5 month ago (didn't
fly with it since) started to develop a strong vibration at higher RPM only.
We had the prop balanced and even tried another one, we upgraded the spark plugs
to the automotive kit. It made a definitive improvement to engine start, pickup
time etc (gotta adjust the idle now). But that damn shaking is still there.
The engine is basically smooth until 70-72% RPM and then vigourously starts to
shake (I didn't really try above 90%). The weird part ? Sometimes, after I try
lower power settings and the go back up in power, it doesn't. And then, picks
it up again.
I'm a little desperate for an explanation here. It's an old engine with low time
remaining on it but still, I'd like an explanation, be it just for educational
purposes.
Many thanks,
Penco
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488284#488284
Message 2
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| Subject: | Re: Engine Vibration |
Does the vibration exist with and without the cowling installed?=C2- How
old are the engine mount rubber shock mounts?=C2- Have you inspected all
8 of them on both sides very carefully along with the bolts and nuts?=C2
- Have you looked closely at the engine mount ring, tabs, bolts/nuts, arm
s, attach points on the arms and the firewall?Dennis
On Wednesday, March 27, 2019, 7:06:57 AM EDT, Penco <osipenco@gmail.com
> wrote:
Hello guys, I'm reviving this topic because I'm coming short of an explanan
tion.
Bit of history :
Bought the aircraft last year. It worked fine and then, some 5 month ago (d
idn't fly with it since) started to develop a strong vibration at higher RP
M only.
We had the prop balanced and even tried another one, we upgraded the spark
plugs to the automotive kit. It made a definitive improvement to engine sta
rt, pickup time etc (gotta adjust the idle now). But that damn shaking is s
till there.
The engine is basically smooth until 70-72% RPM and then vigourously starts
to shake (I didn't really try above 90%). The weird part ? Sometimes, afte
r I try lower power settings and the go back up in power, it doesn't. And t
hen, picks it up again.
I'm a little desperate for an explanation here. It's an old engine with low
time remaining on it but still, I'd like an explanation, be it just for ed
ucational purposes.
Many thanks,
Penco
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488284#488284
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 3
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| Subject: | Re: Engine Vibration |
Hello Dennis,
The engine vibrates whether or not the cowlings are installed.
I didn't check the rubber mounts, I figured if they would be damaged it would shake
at all RPM...
Any specific things I should look for when inspecting them ?
Cheers,
Penco
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488286#488286
Message 4
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| Subject: | Re: Engine Vibration |
I presume you have done the usual compression checks.
Have you removed the rocker covers and looked for broken valve
springs? Have you checked the rocker clearances recently.
As it happens around 70%, that is about where the manifold pressure
goes from vacuum to pressure. Carefully check the intake manifold and
various connections for leaks. Pay particular attention to where the intake
pipes screw into the cylinders and the manifold.
If you have one of the original Russian top dead center tools or can
borrow one, put a 1/4 inch spacer on it and screw it in front plug hole on
and cylinders 4,5 & 6 to check for possible hydrolock.
George Coy
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Penco
Sent: Wednesday, March 27, 2019 7:04 AM
Subject: Yak-List: Re: Engine Vibration
Hello guys, I'm reviving this topic because I'm coming short of an
explanantion.
Bit of history :
Bought the aircraft last year. It worked fine and then, some 5 month ago
(didn't fly with it since) started to develop a strong vibration at higher
RPM only.
We had the prop balanced and even tried another one, we upgraded the spark
plugs to the automotive kit. It made a definitive improvement to engine
start, pickup time etc (gotta adjust the idle now). But that damn shaking is
still there.
The engine is basically smooth until 70-72% RPM and then vigourously starts
to shake (I didn't really try above 90%). The weird part ? Sometimes, after
I try lower power settings and the go back up in power, it doesn't. And
then, picks it up again.
I'm a little desperate for an explanation here. It's an old engine with low
time remaining on it but still, I'd like an explanation, be it just for
educational purposes.
Many thanks,
Penco
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488284#488284
Message 5
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| Subject: | Re: Engine Vibration |
Yes, dry rot; cracking; protruding out beyond the end plates.=C2- Look f
or sagging too.=C2- Look in your engine log book and see if you can figur
e out how long ago they were changed.
Don't forget to carefully inspect the engine mount and all attach points.Ch
eck for loose accessories attached to the engine.=C2- ie: Generator? etc.
Check the cooling louver ring, individual louvers and attach points of the
adjustable arms for looseness.Dennis
On Wednesday, March 27, 2019, 9:24:35 AM EDT, Penco <osipenco@gmail.com
> wrote:
Hello Dennis,
The engine vibrates whether or not the cowlings are installed.
I didn't check the rubber mounts, I figured if they would be damaged it wou
ld shake at all RPM...
Any specific things I should look for when inspecting them ?
Cheers,
Penco
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488286#488286
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 6
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Reading the maintenance manual, it seems like the QS-1 valve is supposed to
go from 0 to 0.95Mpa (138psi) in 2.2 seconds or less...
Is 138psi a good value for the maximum pressure for the brake at the wheel?
Jon
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