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Peter H
Joined: 20 Mar 2007
Posts: 197
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 Posted: Wed May 09, 2007 1:11 pm Post subject: cam shaft bearings |
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Lynn,
I have noticed that my J3300 oil temp is probably too low ie say 50 to 80
deg C . Is that a factor in your bearing failure do you think?
You mentioned a reference to the bearing material. Is there a quality issue
with this product?
When you have a better bearing I would appreciate the product details. Like
you I am out of warranty and want to prepare for independence in the future.
I am based a couple of hours from the factory. Like almost every other
Aviation product supplier I found resistance to any admission of a product
design problem. The best contact I have there is Doug Smith.
Can you tell us about the other problem.?
Regards
Peter H
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Wed May 09, 2007 3:02 pm Post subject: cam shaft bearings |
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Hi Peter-
By the way, the subject line somehow got changed to "cam shaft
bearings" but it really isn't, it's rocker arm bearings/bushings.
My oil temp has always been from (in cruise) 170° F or so, to about
235° F...it got this hot when I forgot and left the oil cooler door
(which I use for quick warm-up in winter months) closed. My EIS
quickly alerted me to this condition, and I opened the door and it
cooled in a minute or so.
I don't know of any quality issue with the product, but I couldn't
find any specs that I understood...go to: Glacier Garlock Bearings,
or look up DU bearings on google. I've lost track of where I found
the temp spec, but it was about 468° F as I recall for these teflon-
coated bronze/steel bushings. I just could not find any load or
pressure spec that I was familiar with. Now I gotta say that I'm not
sure which bearings are used in this engine, but they have been
identified by a knowledgeable source locally as DU bearings. In
reading the service manual (CD) that came with my engine, it says on
p. 46 that "engines from 189 onwards use either 12mm or 15mm wide
GLASIER type bush." The spelling of the word Glacier/GLASIER may be
just a typo, or a completely different bushing altogether, but can
you imagine two bearing companies using this name and not suing one
another?
As my personal disclaimer, I have to say that I'm not sure what
bushings/bearings are used by Jabiru, but the bottom line for me is
they failed. My engine is serial #2062.
The other problem was a scoring of the distributor shaft on the left
bank, and oil leakage on the distributor shaft on the right bank...go
figure. The one that was scored was not leaking a drop, while the
other one was perfectly smooth, but leaked badly. I used a product
called "Speedi Sleeve", which is a thin steel sleeve which is slid
over the grooved shaft, and it effectively increases the diameter of
the shaft at that point .022". This is a ring of steel .011" thick.
This is enough to put just a slight bit more pressure on the seal
lips, and cover over the worn area. They work great!
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/275+ hrs
do not archive
On May 9, 2007, at 5:09 PM, Peter Harris wrote:
| Quote: |
<peterjfharris(at)bigpond.com>
Lynn,
I have noticed that my J3300 oil temp is probably too low ie say 50
to 80
deg C . Is that a factor in your bearing failure do you think?
You mentioned a reference to the bearing material. Is there a
quality issue
with this product?
When you have a better bearing I would appreciate the product
details. Like
you I am out of warranty and want to prepare for independence in
the future.
I am based a couple of hours from the factory. Like almost every other
Aviation product supplier I found resistance to any admission of a
product
design problem. The best contact I have there is Doug Smith.
Can you tell us about the other problem.?
Regards
Peter H
|
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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JohnDRead(at)aol.com
Guest
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| Posted: Wed May 09, 2007 7:13 pm Post subject: cam shaft bearings |
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Hello Listers:
The Glacier DU online catalog has all of the application and spec info. In a past life I used a lot of these bearings with out any problems. They are similar to an Oilite sintered bronze bearing except the "spaces" on the DU are infiltrated with teflon which should provide good boundary layer lubrication if there is brief oil starvation. One problem with oscillating bearings is to get adequate lubrication into the bearing, direct pressure feed is to be preferred over splash lubrication. The latest Jabiru engines have hydraulic lifters so I suppose there is a real need to examine the engine oil for particles as there theoretically there will be zero tappet clearance.
Regards, John Read
See what's free at AOL.com.
[quote][b]
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Thu May 10, 2007 3:00 am Post subject: cam shaft bearings |
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I've just downloaded the 55 pages of the Designer's Handbook from
Glacier Garlock Bearings, here in the USA. Even though the
publication is written in my native English, it all looks like Greek
to me. : ) But I'll study it and see if I can determine why my
bushings might have failed so early. It seems to me on first look
that there needs to be better lube, less mechanical pressure for the
size of the bushing area, or different bushing material. I have
already dreamed up a method for pressure-lubing the area, but so far
that is just dreaming.
It seems to me that an oscillating bushing of this size, under the
load that a rocker arm endures, begs for the best possible
lubrication versus materials compatibility.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/275+ hrs
On May 9, 2007, at 11:12 PM, JohnDRead(at)aol.com wrote:
| Quote: | Hello Listers:
The Glacier DU online catalog has all of the application and
spec info. In a past life I used a lot of these bearings with out
any problems. They are similar to an Oilite sintered bronze bearing
except the "spaces" on the DU are infiltrated with teflon which
should provide good boundary layer lubrication if there is brief
oil starvation. One problem with oscillating bearings is to get
adequate lubrication into the bearing, direct pressure feed is to
be preferred over splash lubrication. The latest Jabiru engines
have hydraulic lifters so I suppose there is a real need to examine
the engine oil for particles as there theoretically there will be
zero tappet clearance.
Regards, John Read
See what's free at AOL.com.
http://www.matronics.com/Navigator?JabiruEngine-List _-
============================================================
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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