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Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 25203
Location: Livermore CA USA
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 Posted: Sun Oct 17, 2010 6:14 pm Post subject: Oil Cooler Mount Cracking... |
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Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112 TTSN hour mark. Most everything looked okay except for one major issue. The outside, lower back mount on the oil cooler is totally cracked off. The outside, lower front mount also has a long crack. At this point, the upper part of the mount seems alright. Also the inside mounts show no signs of cracks. The rear flange on the baffling has a small crack where the left rear part rivets to the back baffle that the oil cooler is bolted to. No oil leaks of any kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth as glass during normal ops), but this doesn't really seem like rotational shake damage. Although, it must be. Obviously I'm going to have to remove the oil cooler and have it repaired (that can be done, right?). But just "fixing" the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole right underneath the oil cooler also had the lug sheered off. There is "service loop" on the cable, but #4 isn't really flexible so its not particular effective. Guess I need more. The point though, is, that it seems like the engine shook pretty hard. I don't see any other signs of "issues" related. The mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN!
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pitts_pilot(at)bellsouth.
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| Posted: Sun Oct 17, 2010 6:48 pm Post subject: Oil Cooler Mount Cracking... |
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Wow Matt! Impressive photo's.
I'm going to guess that it isn't the startup/shutdown motion doing the
damage. I think it's vibration in cruise. Get the prop balanced if you
haven't already. Your airplane will love you for it. As a test, place
a glass of water on the glareshield and look at the ripples ..... change
RPM to see where the ripples are the largest .... and the worst
vibration. Vibration is very subjective.
As for the fix. Well, I'm not in favor of hanging the oil cooler on the
baffle for the reason you found. Things move around a lot. Check the
engine mount for signs that the oil cooler (or even the hoses being
tight) is hitting the engine mount. It looks close per the picture. You
might try to strap the oil cooler aft flange over to the valve cover
screws or over to the screws above the valve cover, or on the inside of
the cooler mount to the engine to stabilize the cooler. My Pitts has
only the corners mounted to the baffle under the air inlet ramp and a
brace up to the cylinder, and it's been trouble free.
I also noticed the spiral wrap prominent in the first picture. Might as
well get rid of it now as it'll dry out and crack off later on. 
Use lacing cord to tie the wires together, or real good ty-raps .....
the cheap ones will go the route of the spiral wrap.
Linn
On 10/17/2010 10:10 PM, Matt Dralle wrote:
| Quote: | Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112 TTSN hour mark. Most everything looked okay except for one major issue. The outside, lower back mount on the oil cooler is totally cracked off. The outside, lower front mount also has a long crack. At this point, the upper part of the mount seems alright. Also the inside mounts show no signs of cracks. The rear flange on the baffling has a small crack where the left rear part rivets to the back baffle that the oil cooler is bolted to. No oil leaks of any kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth as glass during normal ops), but this doesn't really seem like rotational shake damage. Although, it must be. Obviously I'm going to have to remove the oil cooler and have it repaired (that can be done, right?). But just "fixing" the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole right underneath the oil cooler also had the lug sheered off. There is "service loop" on the cable, but #4 isn't really flexible so its not particular effective. Guess I need more. The point though, is, that it seems like the engine shook pretty hard. I don't see any other signs of "issues" related. The mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN!
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jhnstniii(at)aol.com
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| Posted: Sun Oct 17, 2010 6:51 pm Post subject: Oil Cooler Mount Cracking... |
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Matt--Classic problem. Many have mounted the oil cooler on the firewall to avoid it. Some may have come up with ways to beef up the mount/flanges to keep it on the baffle and hopefully you will hear from them. The oil cooler is heavy and the engine shakes a lot on start up and shut down. Another option is to just move it to the firewall and no worries.
LeRoy Johnston RV-6A Esperanza 400 hrs
--
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mr.sun
Joined: 30 Jan 2007
Posts: 85
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| Posted: Sun Oct 17, 2010 7:03 pm Post subject: Oil Cooler Mount Cracking... |
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The oil cooler on my RV7 is mounted the same way. At about 180 hours I had some similar cracking. Not as bad and not on the oil cooler itself, just on the mounts. I've got the 180 hp Lyc so maybe mine doesn't shake as bad. Anyway, the consensus I got locally was that the mass of the oil cooler way out away from the center of rotation of the engine caused a lot of inertia and forces and those four long bolts carry a lot of stress back and forth. The fix for me was to stop drill the cracks and add a piece of angle aluminum bracing to try to get some of the forces transferred to some more sturdy components than the baffles. It is I've got over 500 hours and check things every 50 hours. No changes, cracks stopped. I may add another piece of bracing as well since I saw your photos.
PS: I just finished installing dual 10" Skyviews after my Blue Mountain EFIS died. Painful but I really like it!!
do not archive
On Sun, Oct 17, 2010 at 7:10 PM, Matt Dralle <dralle(at)matronics.com (dralle(at)matronics.com)> wrote:
| Quote: |
Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112 TTSN hour mark. Most everything looked okay except for one major issue. The outside, lower back mount on the oil cooler is totally cracked off. The outside, lower front mount also has a long crack. At this point, the upper part of the mount seems alright. Also the inside mounts show no signs of cracks. The rear flange on the baffling has a small crack where the left rear part rivets to the back baffle that the oil cooler is bolted to. No oil leaks of any kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth as glass during normal ops), but this doesn't really seem like rotational shake damage. Although, it must be. Obviously I'm going to have to remove the oil cooler and have it repaired (that can be done, right?). But just "fixing" the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole right underneath the oil cooler also had the lug sheered off. There is "service loop" on the cable, but #4 isn't really flexible so its not particular effective. Guess I need more. The point though, is, that it seems like the engine shook pretty hard. I don't see any other signs of "issues" related. The mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN! |
#avg_ls_inline_popup { position:absolute; z-index:9999; padding: 0px 0px; margin-left: 0px; margin-top: 0px; width: 240px; overflow: hidden; word-wrap: break-word; color: black; font-size: 10px; text-align: left; line-height: 13px;} [quote][b]
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Vanremog(at)aol.com
Guest
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| Posted: Sun Oct 17, 2010 7:40 pm Post subject: Oil Cooler Mount Cracking... |
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Matt-
I doubt that I could recommend reusing the cooler, as local embrittlement is likely to have occurred deeper into the oil cooler end cap than appears. From your photo it is clear that this was a cyclic fatigue failure as the break appears crystallized and embrittled on both sides of the point of attachment. I believe you will find that the problem is due to the lack of sufficient bearing surface in the original attachment. I would recommend replacing the oil cooler and installing doublers on both sides of the flange to arrest the standing wave in the area of the original attachment.
N1GV (RV-6A Flying 956TTAE Silicon Valley, CA)
A bronze-age myth concocted by goatherders probably isn't a really good thing to base your life on.
In a message dated 10/17/2010 7:20:30 P.M. Pacific Daylight Time, dralle(at)matronics.com writes:
| Quote: |
Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112 TTSN hour mark. Most everything looked okay except for one major issue. The outside, lower back mount on the oil cooler is totally cracked off. The outside, lower front mount also has a long crack. At this point, the upper part of the mount seems alright. Also the inside mounts show no signs of cracks. The rear flange on the baffling has a small crack where the left rear part rivets to the back baffle that the oil cooler is bolted to. No oil leaks of any kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth as glass during normal ops), but this doesn't really seem like rotational shake damage. Although, it must be. Obviously I'm going to have to remove the oil cooler and have it repaired (that can be done, right?). But just "fixing" the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole right underneath the oil cooler also had the lug sheered off. There is "service loop" on the cable, but #4 isn't really flexible so its not particular effective. Guess I need more. The point though, is, that it seems like the engine shook pretty hard. I don't see any other signs of "issues" related. The mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN!
|
[quote][b]
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dsvs(at)ca.rr.com
Guest
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| Posted: Sun Oct 17, 2010 8:11 pm Post subject: Oil Cooler Mount Cracking... |
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Very true but Pacific will replace the entire flange. The comment about lack of surface area is well taken care of by steel washers at the ends of the tubes.
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Vanremog(at)aol.com
Sent: Sunday, October 17, 2010 8:27 PM
To: rv-list(at)matronics.com
Subject: Re: Oil Cooler Mount Cracking...
Matt-
I doubt that I could recommend reusing the cooler, as local embrittlement is likely to have occurred deeper into the oil cooler end cap than appears. From your photo it is clear that this was a cyclic fatigue failure as the break appears crystallized and embrittled on both sides of the point of attachment. I believe you will find that the problem is due to the lack of sufficient bearing surface in the original attachment. I would recommend replacing the oil cooler and installing doublers on both sides of the flange to arrest the standing wave in the area of the original attachment.
N1GV (RV-6A Flying 956TTAE Silicon Valley, CA)
A bronze-age myth concocted by goatherders probably isn't a really good thing to base your life on.
In a message dated 10/17/2010 7:20:30 P.M. Pacific Daylight Time, dralle(at)matronics.com writes:
| Quote: |
Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112 TTSN hour mark. Most everything looked okay except for one major issue. The outside, lower back mount on the oil cooler is totally cracked off. The outside, lower front mount also has a long crack. At this point, the upper part of the mount seems alright. Also the inside mounts show no signs of cracks. The rear flange on the baffling has a small crack where the left rear part rivets to the back baffle that the oil cooler is bolted to. No oil leaks of any kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth as glass during normal ops), but this doesn't really seem like rotational shake damage. Although, it must be. Obviously I'm going to have to remove the oil cooler and have it repaired (that can be done, right?). But just "fixing" the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole right underneath the oil cooler also had the lug sheered off. There is "service loop" on the cable, but #4 isn't really flexible so its not particular effective. Guess I need more. The point though, is, that it seems like the engine shook pretty hard. I don't see any other signs of "issues" related. The mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN!
http://www.matronics.com/Navigator?RV-List |
0123456789
[quote][b]
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bjudge(at)gmail.com
Guest
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| Posted: Mon Oct 18, 2010 7:36 am Post subject: Oil Cooler Mount Cracking... |
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Matt,I had the same type of cracking on my oil cooler after about 60 hrs. I got rid of my standard oil cooler and used a setrab 10 row with swivel angle fittings.
http://www.hrpworld.com/index.cfm?form_prod_id=276,587_823&action=product
http://www.hrpworld.com/index.cfm?form_prod_id=276,587_3397&action=product
It comes with straight in AN fittings but I swapped them out with one 90 and one 45 because that seemed to be the direction that the lines wanted to enter the cooler. I was able to used the standard lines and just make some mods to accept the setrab cooler. I also beefed up the bracing around the cooler with 0.125 angle rather than whatever is standard.
The cooler is about 1/3 the size of standard and so there is much less weight hanging on the baffles. The firewall solution works fine but I really didn't want to have the hoses "working" with the vibrations/shaking of the engine.
550 hrs now and no cracking and my oil temps never get above 200F.
The best part is that I was able to sell the standard oil cooler on ebay for enough to cover the cost of the new cooler and fittings.
Bill Judge
N84WJ RV-8, 550 hrs
rv-8.blogspot.com
[quote]
Time: 07:14:56 PM PST US
From: Matt Dralle <dralle(at)matronics.com (dralle(at)matronics.com)>
Subject: Oil Cooler Mount Cracking...
Dear Listers,
I took the cowling off the 'ol RV-8 today to have a look around at about the 112
TTSN hour mark. Most everything looked okay except for one major issue. The
outside, lower back mount on the oil cooler is totally cracked off. The outside,
lower front mount also has a long crack. At this point, the upper part
of the mount seems alright. Also the inside mounts show no signs of cracks.
The rear flange on the baffling has a small crack where the left rear part rivets
to the back baffle that the oil cooler is bolted to. No oil leaks of any
kind at this point. See attached pictures from my Cell Phone.
So what the heck? The engine shakes quite a bit on startup and shutdown (smooth
as glass during normal ops), but this doesn't really seem like rotational shake
damage. Although, it must be. Obviously I'm going to have to remove the
oil cooler and have it repaired (that can be done, right?). But just "fixing"
the mounting flanges isn't going to solve the "problem".
What are lister's opinion on what's going on here and what could be done to prevent
it?
Interestingly, I noted that the #4 grounding cable that is attached to a bolt hole
right underneath the oil cooler also had the lug sheered off. There is "service
loop" on the cable, but #4 isn't really flexible so its not particular
effective. Guess I need more. The point though, is, that it seems like the engine
shook pretty hard. I don't see any other signs of "issues" related. The
mounts and bolts seem solid and tight.
Thoughts?
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours TTSN!
__[b]
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http://www.matronics.com/Navigator?RV-List |
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