VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 07-17-2018, 08:43 PM
Jim P's Avatar
Jim P Jim P is offline
 
Join Date: Jan 2006
Posts: 932
Default Scored Cylinders

Well, timing is not optimal. I scoped the cylinders after compression check today and found some vertical scoring in the cylinder walls on #1 and #3 with 600 hrs since new. Compression is 74/80 on both and oil consumption has been about 1qt/8-10 hours. I'm wondering about a bad ring that's moving around a bit. I have some carbon build up on pistons, any possibility it's just carbon getting caught by the wall? Thoughts?

And I've review this thread as well: http://www.vansairforce.com/communit...=112722&page=4

Here's #1: https://1drv.ms/u/s!Al5IppCB40wPg4BOajpH2AcctBEdAA
And #3: https://1drv.ms/u/s!Al5IppCB40wPg4BQe1D2Tm4HVc0bUA
__________________
Jim Piavis
RV-7 (Flying!)
http://adap.com/rv7
Redmond, WA

Last edited by Jim P : 07-17-2018 at 09:07 PM.
Reply With Quote
  #2  
Old 07-17-2018, 10:37 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 3,132
Default

#1 certainly looks like either the ring developed a burr (likely at the gap) or has some metal debris embedded in it. You can see a distinct progression and stopping point. The scoring appears to follow the spot as the ring rotates. #3 looks very light from debris that cleared itself. More like scuffing than scoring and not much to be worried about here.

Not much you can do but pull #1 and bore it 010 or 020 over and re-ring. Haven't researched if it is possilbe to take only one cylinder 010 over. The larger piston likely exceeds the 14 gram weight tolerance for balance. However, it is possible they work the oversize pistons to meet the same weight as the STD pistons. There is certainly enough meat on them to make this feasible. These steps are probably not necessary until the oil consumption becomes intolerable or compression drops. This cylinder won't likely make it to TBO though without a lot more oil consumption.

Larry
__________________
N64LR
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress

Last edited by lr172 : 07-17-2018 at 11:01 PM.
Reply With Quote
  #3  
Old 07-17-2018, 10:44 PM
erich weaver's Avatar
erich weaver erich weaver is offline
 
Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,562
Default

Canít see photos without logging in for me.

Erich
Reply With Quote
  #4  
Old 07-18-2018, 05:21 AM
RV7 To Go RV7 To Go is offline
 
Join Date: May 2011
Location: Ontario, Canada
Posts: 101
Default

Oil consumption is ok. Compressions are ok. Any metal in the filter?

Like the other poster's mechanic suggested, I would continue to run it and monitor. FWIW.

Al
Reply With Quote
  #5  
Old 07-18-2018, 08:00 AM
Jim P's Avatar
Jim P Jim P is offline
 
Join Date: Jan 2006
Posts: 932
Default

Quote:
Originally Posted by RV7 To Go View Post
Oil consumption is ok. Compressions are ok. Any metal in the filter?
Filter comes off today, so I'll find out later today.
__________________
Jim Piavis
RV-7 (Flying!)
http://adap.com/rv7
Redmond, WA
Reply With Quote
  #6  
Old 07-18-2018, 08:33 AM
tim2542 tim2542 is offline
 
Join Date: Aug 2009
Location: Redding,Ca
Posts: 615
Default

#3 doesnít look bad, almost normal to have a few minor scratches like that, probably injested some dirt or grit and cleared itself. #1 however looks like classic scoring to me. Perhaps from a cold start or it may have happened during break-in. Is this the first scope on these cylinders? Canít tell from the pic but thatís probably on the thrust side of the piston right? In any case, with a clean filter and with good leak down and oil consumption its a tough call, you could go either way (pull it or run it). Iíll take a guess there will be some minor aluminum particles in the oil filter, if so Iíd pull that one cylinder.
Tim Andres
Reply With Quote
  #7  
Old 07-18-2018, 11:46 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 3,132
Default

Forgot to mention, based upon the depth of scoring (the Pic seems to show some of scratches pretty deep, but tough to see) it is also possible that you have a broken compression ring. There are two of them in there and a leak down test (what aviation calls a compression test, which it really isn't) will often pass with one broken compression ring.

If this is the case, the wear and destruction will come much faster.

Larry
__________________
N64LR
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress

Last edited by lr172 : 07-18-2018 at 02:08 PM.
Reply With Quote
  #8  
Old 07-18-2018, 05:49 PM
Jim P's Avatar
Jim P Jim P is offline
 
Join Date: Jan 2006
Posts: 932
Default

Found that the area is smaller, probably about 5 degrees right at the 1200 position so it's not wrist pin. Pulled the filter and finger screen, both clean, not even any carbon flakes.
__________________
Jim Piavis
RV-7 (Flying!)
http://adap.com/rv7
Redmond, WA
Reply With Quote
  #9  
Old 07-18-2018, 06:49 PM
BillL BillL is online now
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,445
Default

Quote:
Originally Posted by Jim P View Post
Found that the area is smaller, probably about 5 degrees right at the 1200 position so it's not wrist pin. Pulled the filter and finger screen, both clean, not even any carbon flakes.
Jim, One of my cylinders looks similar but less pronounced. There was no rusting before first run or flight. It has good oil control and had only 16 hrs when it was inspected. IO360M1B, new.

Is there any chance yours has set for over 30-60 days to get any rust in the cylinders? I am sure mine did not, so just checking.

My first filter was concerning, but the second was very clean. Do you get a regular oil analysis? That might help with a more refined monitoring tool.

BTW, as a career engine guy, it looks bad, but unless it has elevated metal, loss of compression (leak test), there is no overt indication that it is something that is progressing to failure. If it was a class 8 truck engine, it would not last, not sure about these Lycs.
__________________
Bill

RV-7
1st Flight 1-27-18
Phase II 8-3-18
Reply With Quote
  #10  
Old 07-20-2018, 06:14 PM
Jim P's Avatar
Jim P Jim P is offline
 
Join Date: Jan 2006
Posts: 932
Default

Well crud! Bagged the trip to OSH to pull this cylinder - rather not be worrying about this over the Montana Rocks. Grrrrrr!
__________________
Jim Piavis
RV-7 (Flying!)
http://adap.com/rv7
Redmond, WA
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 05:44 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.