Today's Message Index:
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1. 09:12 AM - Re: Compression (Noel)
2. 04:52 PM - Re: Compression (Roger Lee)
Message 1
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I=99ve tried dynamic tests over the years and found them to be
more lying than a politician on the campaign trail. Also when they do
actually find a low cylinder you still have the problem of finding where
compression is lost.
Noel
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of T.
Graziano
Sent: 07 July 2009 17:23
Subject: Re: JabiruEngine-List: Compression
Bobby,
Have you tried "dynamic"compression testing (see compression testing
Page 18 of Jab Instruction & Maintenance Manual, Rev 3 dated 18 Jul
2008. (this is for the solid lifter 3300A - suspect the hydraulic lifter
is the same)
Para 5.7.8 "Compression Testing: Condition of compression can be done
by a compression gauge. Wide open throttle, engine warm. Turn over on
starter. Below 90 psi would indicate removal of head and possibly
cylinder>
At my last annual, almost a year ago, I read 160#, 160#, 160#, 165#, 165
and 170# on my Jab with 408 hrs. Not much, if any, change from the
years before.
Tony Graziano
ZodiacXL/Jab3300A - Ser 33A644; N493TG; 509 hrs.
----- Original Message -----
From: BobbyPaulk@COMCAST.NET
Sent: Tuesday, July 07, 2009 10:30 AM
Subject: JabiruEngine-List: Compression
all,
i have just taken differential compression test on my 3300A with 84 hrs
S.N. 1141.( Conditional Inspection ) No. 2 and 6 had 75 & 77 the rest
had low to mid 60's. i could rock the prop to seat the rings and get
another 5 ~ 6 lbs. while on #5 near the oil collector bottle i could
feel air out the bottle vent so the air is going thru the rings and
pressurizing the crankcase. Test was on a cold engine setting up for
about 2 weeks.
my question is at 84 hrs could this many cylinders have rings not yet
seated. last year all were in the high 70's. the engine starts fine as
always and i have not noticed any power drop. the first 40 hrs or so the
engine ran too lean and it was difficult to control high EGT / CHT's.
any ideas??
Bobby
601 XL
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Message 2
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Hi Guys,
Are you making sure to test with an engine up at operating temps. Shouldn't be
cold.
--------
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=252386#252386
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