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  #1  
Old 05-30-2016, 12:19 PM
petehowell's Avatar
petehowell petehowell is offline
 
Join Date: Jan 2005
Location: MN
Posts: 2,297
Default Exhaust Valve Trauma

Well it finally happened...... After 1600 trouble-free hours with my O-320, a little rain has fallen. Made two great trips to Iowa last weekend and got home on Sunday and dropped the oil for the change. I made the mistake thinking on the way home how great she was running.......

I did my usual compression check and saw 77/80 on 2-3-4, but #1 was 60/80. Leak out the exhaust - grrrr (all 77/80 50 hrs ago). Talked to those more smarter than I (Professors Horton, Lane, Peterson, et al) and consensus was fly it a bit, test it again - that did not help - no joy. Exhaust leaks don't heal and need to be dealt with.

Made a "Mike Bullock Wonderbar Special" (TM) valve compressor(seriously, was that a great writeup he did or what!)



Then pulled the springs and keepers. Valve was silky smooth in the guide and seated well when pulled back, so that was good. Dan suggested spinning and banging the valve on the seat just in case there was a piece of junk on there, so we tried that and shot this video thru the top plug hole with my celly.

https://www.youtube.com/watch?v=0dLEYZ1kRfo

I think you can see the problem area if you look closely, but do offer up any observations of the valve sealing surface.

We did try a compression check after doing the "Spin and Bang" - same story 60/80 and exhaust hiss. Took me less than 30 min to get the baffling and other stuff out of the way to free up #1 Jug (it looks like the easiest of all to get free), then I had to go out of town for the weekend. Jug will come off tonight with the help of Alex P.

New jug looks to be $1000 or so. So New Cylinder, rebuilt cylinder, or fix the valve and seat........that is the question....please offer opinions, rationale and cost estimates.........

To answer the questions you are all dying to know....

- These are ECI Group B Cyls from 2005
- LOP other than takeoff, CHTS balanced and in the 325degF range
- 50+% Mogas, 92 no EtOH
- Carb
- E-Mag/Pmag
- Rattle can Primer
- Nosewheel
- Dog hair in the cockpit

Thanks for commiserating................ Ha!
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Amateur Plane - RV-9A N789PH - 2450+ Hrs
Amateur Radio - KD0CVN
Doggies Delivered - 25+
St. Paul, MN

Last edited by petehowell : 06-01-2016 at 10:16 PM.
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  #2  
Old 05-30-2016, 01:51 PM
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Ironflight Ironflight is offline
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Default

Oh the awful 1600 hour decision........

In the old days, rebuilding/fixing/overhauling jugs was just the norm - to try and get to TBO. But with a complete stud assembly (jug, piston, valves) for $1,000? Why bother! But then.....you've got one brand new jug and three others at 1600 hours! I had this same dilemma on the Val at 1400 hours, and decided that since the bottom end was first-run, and doing great, I'd bite the bullet, put four new jugs on (mine was a ring issue - all the jugs were suspect), and start doing oil analysis to look at the bottom end when I got closer to TBO. The first-run bottom end can go a LONG time.

The real question is if there is a good cylinder shop nearby that can just re-do the exhaust valve and seat for you for a few hundred bucks. If they can, and it were me, I might give that a try on this FIRST jug. If you start seeing a pattern, with another jug doing the same thing, then keep the whole engine in sync with an O/H or at least a top O/H with four new jugs.

It's been forty years since I lived in the Cities, so I have no idea if there's a good cylinder shop aroudn anymore.
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  #3  
Old 05-30-2016, 02:07 PM
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Sam Buchanan Sam Buchanan is offline
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Pete, I will leave the valve advice to others (my cylinders have 1200 hrs...) but I missed the "Mike Bullock Wonderbar Special" article. Where do I find it?
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  #4  
Old 05-30-2016, 02:12 PM
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rvn817j rvn817j is offline
 
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Quote:
Originally Posted by Sam Buchanan View Post
Pete, I will leave the valve advice to others (my cylinders have 1200 hrs...) but I missed the "Mike Bullock Wonderbar Special" article. Where do I find it?
Sam...try this http://www.vansairforce.com/communit...t=mike+bullock
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  #5  
Old 05-30-2016, 03:05 PM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by rvn817j View Post
Thank you, I had forgotten about that thread.

Interestingly, one of my Millennium cylinders had tight valves at ~140 hrs. We pulled the cylinder to ream the guides and it has been good for over a dozen years. The other cylinders have never needed attention, never could come up with a good reason why only one cylinder tightened up.
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  #6  
Old 05-30-2016, 07:12 PM
Ron B. Ron B. is offline
 
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My buddy with a twin SuperCub to mine had one of those B group ECI jugs blow off, on take off (successful water landing thankfully). I personally do not see any choice, but that's me. We replaced 8 jugs at that time (same engine).
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  #7  
Old 05-30-2016, 07:21 PM
BillL BillL is offline
 
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Hey Pete - just to me sure you might get a good visual on the other ex valves. If they are not crescent mooning, then minimal repair (like Paul said) and on to the real TBO.
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  #8  
Old 05-30-2016, 08:41 PM
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petehowell petehowell is offline
 
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Default You tube.....

Of course there is a video for this....

https://www.youtube.com/watch?v=7g1MpHpxVwo
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  #9  
Old 05-30-2016, 10:28 PM
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AJ85WA AJ85WA is offline
 
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Default Lapping with jug on

Funny enough I was actually looking at this video of Jim doing a repair without removing the jug.

Not saying its going to work or the best way, just that it is interesting.

https://www.youtube.com/watch?v=4PM8PFwYJmw
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Last edited by AJ85WA : 05-30-2016 at 10:34 PM. Reason: changes
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  #10  
Old 05-31-2016, 04:58 AM
pa38112 pa38112 is offline
 
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Gibson's in El Reno, OK can overhaul the cylinder for $345 with a two day turn around. http://www.gibsonaviationok.com/

If you haven't already pulled it I would use a borescope to inspect further. The in-place lapping might work and is better than removing a jug, but you would want to see the seat first.
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