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1. 08:18 AM - Oil pressure videos (James, Clive R)
2. 08:30 AM - Re: [jabiruengines] Summary - Oil Pressure troubleshooting day with Clive at Ludham (James, Clive R)
Message 1
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| Subject: | Oil pressure videos |
You may have seen other postings I have made regarding the pressure
within a Jabiru engine oil system.
I feel those of us with engines which have pressure pulsing created by
the relief valve have an opportunity to improve the situation.
I believe the pressure pulses are responsible for many of the cooler
failures that have been experienced around the world.
Pulsing with hydraulic systems can spoil flow and create back pressure
and fatigue.
I am working on an alternate shape to the relief valve tip which will, I
hope, eliminate the pulsing.
When I have done this successfully I will share the design with
everyone.
I have been in touch with Jabiru and suggested it was worth looking into
but as yet have had no indication they feel it is an issue, their
suggestion seemed to point to an issue with coolers only.
Below is listed the videos.
Late 2200 with hydraulic tappets:
http://www.youtube.com/watch?v=Kf5FUScRSIM
Early 2200 solid lifter, serial number 596
http://www.youtube.com/watch?v=oWI3I5iOq8k
Early 2200 solid lifter no 2, 700 series
http://www.youtube.com/watch?v=c_5or47YxcY
Mid 2200 solid lifter no 2, 1300 series
http://www.youtube.com/watch?vmVuaWk4Ao
3300 solid lifters Serial number 828, the oil cooler on this engine has
distorted.
http://www.youtube.com/watch?v=k6LgiSakBSk
3300 with Hydraulic lifters serial number 1460
http://www.youtube.com/watch?v=q_TCQtrfUHc
3300 with Hydraulic lifter with relief valve plug shaped to a point,
engine 1460 again, compare this to the previous video, look at the sweep
of the valve needle.
http://www.youtube.com/watch?v=bnRlyl20HaY
See here for still photos of the valve tip, this was simply done with
the valve in a drill chuck and a needle file.
http://groups.yahoo.com/group/jabiruengines/photos/album/439839736/pic/l
ist
A couple at attached for the Matronics listers.
<<pointed relief valve plug.jpg>> <<standard shape relief valve
plug.jpg>>
If anyone is curious about their engine the gauge is an 1/8 npt, 10 bar
- 160 psi and you can see how quick and simple the test is. It would be
good to find when the pulsing started.
It doesn't seem to be there up to late 700 2200 engines. But is there by
mid 1300s. I've only had access to 6 engines since I started looking
into this.
When engine is running the pulsing is still there but the gauge is hard
to read as the needle is a complete blur. That is why I did these tests
with engines cranking.
The pulse on my 3300 is a drop of 20 psi where the valve lifts and then
it re-seats allowing the pressure to build again. I could see this when
turning the prop by hand.
Regards, Clive
Message 2
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| Subject: | RE: [jabiruengines] Summary - Oil Pressure troubleshooting |
day with Clive at Ludham
Just to add to Dean's note. His 2200 engine seems to be one of a very
few where there is excessive oil flow within the engine, you might call
it leakage.
Where this oil is going we don't know but as we understand it sealant
was used internally and perhaps it hasn't been used consistently. Though
that is just an idea.
Dean's main concern with his explanation to everyone is his oil pressure
used to look really good and only when he took the oil cooler off did he
see a low pressure.
>From this we feel his oil cooler loop was giving him a false
'satisfactory' reading by creating backpressure to be read by the sender
on the pump discharge.
It is this phenomena why it is now thought to be a good idea to read the
pressure from the engine gallery.
Most of us will see healthy pressure in both places and so it isn't a
concern, however it was only by reading the 'lists' that made Dean
investigate to see what he had on the gallery reading.
Also the Jabiru engine seems to be very tolerant of low oil pressures,
again a nice thing to know.
The extra oil available from fitting a 3300 pump to Dean's 2200 engine
has enabled the back pressure to build so it can be read on a hot engine
at tickover, this suggests a surplus which we weren't seeing before and
was therefore a worry.
I have seen 'Steve's' thermo OCA and it looks a neat bit of kit and I
would like to fit one to my 3300 engine.
I feel it's effect on the optimum cooling is second only to the great
effect it will have on oil pressure delivery for any engine it is fitted
to.
Regards, Clive
From: jabiruengines@yahoogroups.com
[mailto:jabiruengines@yahoogroups.com] On Behalf Of D
Sent: 16 September 2011 13:32
Subject: [jabiruengines] Summary - Oil Pressure troubleshooting day with
Clive at Ludham
Hello All,
I just want to summarise my day with Clive at Ludham Norfolk, his home
airfield working on oil pressure (OP) and oil temperature (OT) problems
on my engine (serial number 1157 solid lifters large fins). It may of
some interest to others out there experiencing low oil pressure issues
or normal OP's with a cooler fix (head in the sand approach).
OP's have always been around 3-4 at tick over and cruising a 2900 with
an earls oil cooler, braided =BC" pipes and OCA with a relief hole
(around 3/32"). OT's hardly ever reached the optimal upper 80's,
normally settling at around late 70's.
I was shocked to find OP dropped significantly at cruise to around 2.5
bar max when i removed the OCA and oil cooler. Tick over OP's were at
0.4 bar or less. I moved the OP sensor to the galley and pressures seen
were alarmingly low. I did a lot of experimenting and eventually
resorted to paying Clive a visit as I had plenty of conversations about
OP's and OT's with possible solutions.
Here is Clive summary of our days trouble shooting jabiru's OP and OT's
problems:
Well we had an interesting day with Dean's engine, I hazard to say a
completely successful one as the situation at the end is still not
ideal. Dean does now have more than a bar oil pressure on tick over.
The `relief valve' was undoubtedly leaking precious oil which we proved
by blanking it off with shim. However the significant oil loss isn't
highlighted unless flying with the engine up to temperature. The lack of
damage to the engine suggests there has been sufficient oil available at
all times to feed the critical parts but the 0 psi on tick over on
finals was a worry.
Incidentally we dropped off a rocker cover and got oil on our boots.
So after replacing the relief valve with my brass one and a new seat and
getting reasonable readings on the ground the flight test showed the
problem was still there, generally the pressure reflected the revs and
was between 3.8 and zero depending on what the engine was running at.
Zero on idle on final (wince).
After confirming with Roger it was OK to do a swap we fitted my Esqual's
3300 oil pump. Interestingly it looked like the relief valve was now in
the game as the pressure never went above 4.1 bar, though I suppose that
could have been all that was produced. The pressure
did look as if it was held at that maximum though.
After flight test and flying home Dean has confirmed his has a readable
pressure of 1.8 bar (?) on tick over. When flying, His oil temperatures
were high however, higher than before the big pump was fitted (120
degrees Celsius +). I have suggested that now there is oil available to
spray about then maybe that oil is picking up heat that it wasn't
before.
One other thought Dean, the `leakage' in the engine is increased when
the engine is at running temperature so there may be better pressure
developed when the cooler gets the temperature down.
Roger also made a great observation, the new Thermo OCA will be ideal
for your engine, to optimise the flow to the engine and keep the engine
cool should further enhance the pressure situation for you.
Suggested way forward, fit the cooler loop, ground run and read gallery
pressure, flight test and get some readings. After getting a baseline on
the cooler diff put the sender back in the original position. I think
you have a bypass hole in the OCA already. Fly the plane, when available
fit the thermo OCA. Fly the plane some more!
At some point I'd like to check what we are seeing regarding the relief
valve and potential pulsing, if we still have a shortage of oil then
optimising the relief valve performance (make it a regulator) can only
help things.
Good to meet Dean, and a fun (but messy day), still need to do some
flying when we next meet as it's many years since I flew in an SK.
Thanks for lunch!
It seems that Jabiru has got this one wrong and it would be good to see
them address OP issues with their engines. Introducing an oil cooler
leads to an increase in pressure (likely to be due to back pressure) but
that is definitely not ideal and does not translate to an increase in
galley pressure which is essential to keep the journals well oiled and
optimal engine (heads, cylinder and any other moving parts lubricated).
As Roger mentioned, this is likely to increase wear and result in
overheating (secondary role played by oil sloshing around) which could
eventually lead to premature engine failure.
I appreciate Clive and Roger taking time to run through the
technicalities of engine cooling and lubrication, all very valuable
stuff and as clearly given me a better understanding on how my block
runs! Happy flying ...
__._,_.___
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