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  #111  
Old 02-16-2011, 05:05 AM
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DanH DanH is online now
 
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Quote:
In addition to the carbon, all four (including the new one) pistons are scuffed on the sides, and appear to have metal (probably aluminum) embedded in the pistons.
Is the mystery metal embedded in the crown or the skirts?
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RV-8 SS
Barrett IO-390
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  #112  
Old 02-16-2011, 08:13 AM
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Greg Arehart Greg Arehart is offline
 
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Dan,

In the skirts. The hypothesis is that the metal (aluminum, not steel) got into the oil (presumably rocker boss bits that went through the oil drain line) and was splashed onto the cylinder walls etc. by the movement of the crankshaft. I have the spray nozzles in the engine, but obviously any metal going through the pressurized oil system would have been caught by the filter.

greg
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  #113  
Old 02-16-2011, 10:21 AM
mahlon_r mahlon_r is offline
 
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Only times I have seen metal in the skirts is from cam lobe and tappet face failure. Has anyone glanced at the cam?
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Mahlon
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  #114  
Old 02-17-2011, 11:17 AM
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Greg Arehart Greg Arehart is offline
 
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Mahlon,

We looked at the cam after pulling the cylinders and nothing obvious, but it will get a close scrutiny when we open things up.

greg
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  #115  
Old 02-20-2011, 09:42 AM
detlef lili detlef lili is offline
 
Join Date: May 2005
Location: Albuquerque
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Thanks Greg, for the update.

I still watch this thread since I have the same engine, with the same time and also run mostly on car gas. You fly mostly over rough terrain and we a lot over water. (We also visited Reno last summer, we were invited by Chuck Harder)
And we don?t like any surprise flying over the ocean. So we are very interested in the results. Please keep us informed.

Detlef
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  #116  
Old 07-09-2011, 04:07 PM
Larry L Driver Larry L Driver is offline
 
Join Date: Jul 2011
Location: Phoenix, AZ
Posts: 7
Default Another Superior Rocker Boss Failure

Hi, All.

I was just made aware of this posting by another member.

I too experienced a rocker boss failure on my Superior XP I0-360 yesterday while flying cross country over Missouri. My RV7 first flew in July 2005 and has 675 hours.

I was able to get to an airport 11 miles north under very reduced power. Removed the cowl and saw what Greg described and illustrates in his photos. Failure looks identical, including the much thinner side of the casting of the boss.

I had had an incident of roughness on the previous leg that went away after enrichening. I also thought it might be contaminants or water in the fuel. Like Greg, there was no indication of something catastrophic... just a rough engine. Doesn't appear that I lost much oil. Just some spray inside the cowl. Oil pressure remained normal. Haven't checked the oil level. Was en route to a business meeting and had to leave plane behind. Will definitely check the oil on return, though.

Larry
N977RV
Phoenix AZ
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  #117  
Old 07-09-2011, 10:37 PM
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Larco Larco is online now
 
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I have seen pictures of both Larry's and of Greg's failure and they look identical. What would be interesting is if they are close in serial numbers. Could you both please post that info, I have a feeling that there are more failures ahead of us. Hopefully I'm way off base. Larry S
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  #118  
Old 07-10-2011, 05:10 AM
Larry L Driver Larry L Driver is offline
 
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Location: Phoenix, AZ
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Default Cylinder Serial Numbers

I will certainly post my serial number for comparison. It will be sometime after next Friday when I get back to the airport where I had to leave the plane for repair.
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  #119  
Old 07-10-2011, 08:56 AM
RV8R999 RV8R999 is offline
 
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Default Superior Airparts?

What is Superiors position on this matter? You guys talk to them yet?

I have an Xp-360 as well with about 200 hrs since new.
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  #120  
Old 07-10-2011, 08:19 PM
Larry L Driver Larry L Driver is offline
 
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Ken,

I've had numerous e-mail conversations with Superior. They're convinced it's a stuck valve.

I'm in a total quandary as to how to fly the airplane now. I always fly LOP below 70% power. Plugs has always been pretty clean. So carboned up valves doesn't seem likely.

Not a very comforting thought that you might have the same thing happen without any warning over less friendly terrain.

Hopefully, I'll learn more when we change the cylinder later next week. Although it sounds like nothing definitive ever developed in Greg's case.

Maybe we should have a "Superior Engine Owners Get-Together" at AirVenture.
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