Today's Message Index:
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1. 09:36 AM - insufficient rocker chamber greasing ????? (avidflyer01)
2. 11:25 AM - Re: insufficient rocker chamber greasing ????? (John Loram)
3. 12:50 PM - Re: insufficient rocker chamber greasing ????? (avidflyer01)
4. 01:47 PM - Re: Re: insufficient rocker chamber greasing ????? (Terry Fogelson)
5. 03:52 PM - Key Switch for JAB 3300 (pequeajim)
Message 1
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| Subject: | insufficient rocker chamber greasing ????? |
hi guys, I would like to share some very worrying facts about my engine (2200 w/hyd
lifters) and maybe get some answers from those who have already been there.
I have just completed reassembling my engine after replacement of all valve guides
(both of N2 were completely worn out at 100hrs, others were replaced as precaution).
Today I started it and run for 5 min at 1200-1500rpm, then stopped
and made a close inspection. When I removed tapper covers, I discovered there
was some oil, as it should be the case, in rear rocker chambers (Ns 3 and 4)
but the forward ones were AS DRY AS PRIOR TO ASSEMBLY.
The airplane was sitting almost level, with tail slightly lower, maybe 5. Oil level
was slightly above minimum, as per SB 013-1. The oil pressure was (as always
both in flight and at idle) at 35psi.
After checking that the T junctions on oil feed line were not blocked and some
more thinking, I tilted the airplane more on the nose (3 nose down), cleaned rocker
chambers and run it again for 1 min at 1200rpm.
This time forward rocker chambers were correctly flooded with oil while the aft
ones were virtually dry, except a few drops.
I sincerely hope that at a higher power setting the amount of oil carried thru
the feed tube from under the cylinders is sufficient to spread it correctly in
the T-junction to grease both rocker chambers (I have so far always seen oil
in rocker chambers, although there was always more of it in the rear ones my
plane is a taildragger).
But the worrying truth seems to be that when warming the engine or taxiing at
low rews (and even more so in a taildragger, although already 5 tilt seems to
make a difference), there are good chances that fwd cylinder rockers and valve
guides run dry!!!! My guess is that the quantity of oil delivered is insufficient
and it only runs down the slope, towards the cylinder that is lower.
This could be by the way one of the possible explanations why my valve guides were
ruined after 100hrs and that my rocker bushings also show some premature wear.
Has anybody any comment on these facts? Pete, Andy, do you guys consider it normal
that the whole rocker chamber is not bathing in oil????? Any similar problems
found/cured????
Once at that subject, the SB 013-1 explained to us that vent holes and correct
routing of the sump breather were supposed to enhance the return of oil from rocker
chambers back to the sump, as if too much oil was delivered to the heads.
Seemingly, I have the opposite problem (or at least I do have it on lower revs)
isnt there a restriction between the main oil galley and the two tubes feeding
oil to rocker chambers, that could be increased????
I dont like the idea of running idle with no oil in my rockers/valves.
Any input, guys????
Martin
Avid flyer w/Jab 2200
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=129820#129820
Message 2
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| Subject: | insufficient rocker chamber greasing ????? |
Martin:
What you've encounter is a documented problem with Jabiru engines in tail-draggers,
and has been discussed in the past on this list.
Simply described; when the tail is down and the oil is thin (hot), the oil flows
up the oil tubes to the heads and then, at the 'T' it flows 'down hill' to the
rear cylinders with the forward cylinders running dry.
Colin Hales, the English aeronautical engineer who's 'epic' flight from England
to Australia in a Jabiru 2200 powered Rankin KR2 is mentioned in the December
2002 JabaChat, describes the problem thusly: "... But there is one problem that
we had as a tail dragger that happened to us and Jabiru knows about, but don't
tell. We had to taxi for half an hour after landing. With hot, thin oil at
idle, all the oil that is supplied to the rockers through the supply tubes runs
to the back cylinders and the fronts run dry. Normally there is enough oil
floating about to do the necessary lubrication and the oil when cool and thick
gets everywhere. But do not run your engine for long after landing. The front
rockers will run dry and heat up and damage them selves. Happened to us in Bali.
..."
Buy the way, if you can find Colin's auto-biography of the trip, it's a fascinating
read. He had it published on a website that I have lost track of. He describes
the above problem in much greater detail.
Regards, -john-
> -----Original Message-----
> From: owner-jabiruengine-list-server@matronics.com
> [mailto:owner-jabiruengine-list-server@matronics.com] On
> Behalf Of avidflyer01
> Sent: Sunday, August 19, 2007 9:36 AM
> To: jabiruengine-list@matronics.com
> Subject: JabiruEngine-List: insufficient rocker chamber greasing ?????
>
> --> <vegayacht@club.fr>
>
> hi guys, I would like to share some very worrying facts about
> my engine (2200 w/hyd lifters) and maybe get some answers
> from those who have already been there.
> I have just completed reassembling my engine after
> replacement of all valve guides (both of N2 were
> completely worn out at 100hrs, others were replaced as
> precaution). Today I started it and run for 5 min at
> 1200-1500rpm, then stopped and made a close inspection. When
> I removed tapper covers, I discovered there was some oil, as
> it should be the case, in rear rocker chambers (Ns 3 and 4)
> but the forward ones were AS DRY AS PRIOR TO ASSEMBLY.
> The airplane was sitting almost level, with tail slightly
> lower, maybe 5. Oil level was slightly above minimum, as
> per SB 013-1. The oil pressure was (as always both in flight
> and at idle) at 35psi.
> After checking that the T junctions on oil feed line were not
> blocked and some more thinking, I tilted the airplane more on
> the nose (3 nose down), cleaned rocker chambers and run it
> again for 1 min at 1200rpm.
> This time forward rocker chambers were correctly flooded with
> oil while the aft ones were virtually dry, except a few drops.
> I sincerely hope that at a higher power setting the amount
> of oil carried thru the feed tube from under the cylinders is
> sufficient to spread it correctly in the T-junction to grease
> both rocker chambers (I have so far always seen oil in rocker
> chambers, although there was always more of it in the rear
> ones my plane is a taildragger).
> But the worrying truth seems to be that when warming the
> engine or taxiing at low rews (and even more so in a
> taildragger, although already 5 tilt seems to make a
> difference), there are good chances that fwd cylinder rockers
> and valve guides run dry!!!! My guess is that the quantity of
> oil delivered is insufficient and it only runs down the
> slope, towards the cylinder that is lower.
> This could be by the way one of the possible explanations why
> my valve guides were ruined after 100hrs and that my rocker
> bushings also show some premature wear.
> Has anybody any comment on these facts? Pete, Andy, do you
> guys consider it normal that the whole rocker chamber is not
> bathing in oil????? Any similar problems found/cured????
>
> Once at that subject, the SB 013-1 explained to us that vent
> holes and correct routing of the sump breather were supposed
> to enhance the return of oil from rocker chambers back to the
> sump, as if too much oil was delivered to the heads.
> Seemingly, I have the opposite problem (or at least I do have
> it on lower revs) isnt there a restriction between the
> main oil galley and the two tubes feeding oil to rocker
> chambers, that could be increased????
>
> I dont like the idea of running idle with no oil in my
> rockers/valves.
> Any input, guys????
> Martin
> Avid flyer w/Jab 2200
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=129820#129820
>
>
>
>
>
>
>
> Photoshare, and much much more:
>
>
>
>
>
Message 3
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| Subject: | Re: insufficient rocker chamber greasing ????? |
thanks John.
Taildragger configuration makes it certainly worse, but my remarks concern the
airplane that is as level as an airplane can be ( +5 or -5 from horizontal keeps
fwd or rear cylinders dry....).
They also concern cold oil (engine just started); hot oil is probably worse.
I am tempted to think (but no proof to that) that keeping higher rpm while warming
up or taxiing could help.
martin
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=129846#129846
Message 4
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| Subject: | Re: insufficient rocker chamber greasing ????? |
A bandaid that will help is a preoiler. Certified
ones are expensive, but if you adapt an auto one they
are reasonable. http://www.autoenginelube.com/ is one
that uses engine oil pressure to charge an accumulater
and then it traps the pressure after the power is shut
off. one to three quart accumulators.
Terry
--- avidflyer01 <vegayacht@club.fr> wrote:
> "avidflyer01" <vegayacht@club.fr>
>
> thanks John.
> Taildragger configuration makes it certainly worse,
> but my remarks concern the airplane that is as level
> as an airplane can be ( +5 or -5 from horizontal
> keeps fwd or rear cylinders dry....).
> They also concern cold oil (engine just started);
> hot oil is probably worse.
>
> I am tempted to think (but no proof to that) that
> keeping higher rpm while warming up or taxiing could
> help.
>
> martin
>
>
>
>
> Read this topic online here:
>
>
http://forums.matronics.com/viewtopic.php?p=129846#129846
>
>
>
>
>
>
>
>
> browse
> Subscriptions page,
> FAQ,
> http://www.matronics.com/Navigator?JabiruEngine-List
>
> Web Forums!
>
>
>
>
>
Park yourself in front of a world of choices in alternative vehicles. Visit the
Yahoo! Auto Green Center.
http://autos.yahoo.com/green_center/
Message 5
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| Subject: | Key Switch for JAB 3300 |
What key switch are you guys using with your 3300?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=129878#129878
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