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  #51  
Old 03-06-2012, 08:15 PM
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Walt Walt is online now
 
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Quote:
Originally Posted by Bubblehead View Post
Do you have a boroscope that can get into a cylinder?
Sorry no boro
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  #52  
Old 03-06-2012, 08:37 PM
zav6a zav6a is offline
 
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Default Fuel flow

I presume you have a monitor. Does it fluctuate one way or another from normal during these episodes?
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  #53  
Old 03-07-2012, 07:21 AM
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Bubblehead Bubblehead is offline
 
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The fuel flow monitor is currently out of the system. I was trying to remove possible contributing components. When it was in the system i would get some small fluctuation during normal ops but Airflow Performance said that variation was normal.

The EGT spikes when I reduce power so the fuel flow is changing anyway so I woukd not be able to tell change is due to throttle reduction and what is due to the root cause.

The EGT spike when reducing throttle normally means an induction leak, and we've fixed some of those. I will pull the intake tube for #3 today again and check it. I've had 2 cracked intake tubes and several bad o-rings.

I'll put the fuel flow transducer back in today since that apparently is not the problem.
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RV-8 180 hp IO-360 N247TD with 10" SkyView!

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  #54  
Old 03-07-2012, 08:44 AM
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Walt,

I have a HF 8mm wide inspection camera with a mirror that you can use. I used it during my last condition inspection and could see the valves using it.

Let me know and I can run it over during lunch today -- TJ
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  #55  
Old 03-07-2012, 10:16 AM
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Bubblehead Bubblehead is offline
 
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TJ - Walt may already at Hicks and I am getting ready to leave Keller for Hicks. I could come by 52F if that's where you are located and pick it up.

512-850-8339 cell if that works for you. I appreciate the offer.


In a post in another thread Mel says to beware of using SCAT tubing in the intake. I have a very old FAB setup with what I think is SCAT tubing.

What should I be using?

The original thread and posting is here http://www.vansairforce.com/communit...90&postcount=3
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  #56  
Old 03-07-2012, 10:22 AM
frazitl frazitl is offline
 
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Default Just read the whole thing...

Wow, you have certainly had a time with this. I had an issue early on in Phase I. Could hardly keep the engine running on final or on the ground thereafter . Both cylinders on one side had were acting up (don't remember which side or whether they had gone hot or cold EGT). After talking with Precision, I pulled the top off the spider and found some small black specs of ?? in the spider. I cleaned it all up including flushing the injector lines. Problem solved. Did you ever check out the spider?? This could be an issue especially since the servo inlet filter wasn't always doing it's job...
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Last edited by frazitl : 03-07-2012 at 10:24 AM. Reason: clarification
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  #57  
Old 03-07-2012, 01:26 PM
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Thanks for the idea, Terry. Spider and servo were both rebuilt and tested last month by AFP. They didn't find any particular problem but they had an unknow but large number of hours on them and so I had them rebuild the system.

We also flow checked nozzles and lines last month and all checked ok. I might swap #3 and #1 nozzles and see if the problem moves, but I doubt that is the problem. All the nozzles were new as of a year ago.
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  #58  
Old 03-15-2012, 08:47 AM
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Quote:
Originally Posted by Bubblehead View Post
So where do I go from here? Fuel injections and mags were rebuilt, engine driven fuel pump new, old hoses replaced, fuel filter checked and fuel tank vents are ok. Compression checked fine after the last occurance and the exhaust valve wobble test was passed.

I think i'll go back to drinking. I was better at that than owning/maintaining an airplane. It was a lot cheaper too.

Where do you go?
Don't be discouraged. Don't go back to drinking :-) Re-read the PM I sent you as you put it back together. Even if you happened to fix the earlier problem, it is very likely to have things go wrong after having so many things apart.

This very thing happened to me recently with an automobile. A dealer installed a new short block under warranty. The mechanic was "our best". About a month later, I had steam pouring out from fender wells and grill. A small coolant hose never had the clamp moved the inch or so back up onto the noozle, so the clamp couldn't do it's job, the hose worked loose and came off. Bummer, yes. Unexpected, not at all. Changing a short block involved touching every single engine support system and accesory.

Instrumentation- it is important diagnostic tools are available so this can be figured out. Great that you have an engine monitor, you've already narrowed it to #3. Fuel pressure is steady? Pressure in range? Fuel flow?(that needs to go back on), so you can see if fuel is different when rough than not rough.

Lastly, try contacting Mike Busch. He started a business that occupies a very needed niche. Owners of certified Cirrus aircraft were finding themselves facing $5K annuals. Much of the proposed maintenance is not in the owners best interest. Mike helps owners sort out what is in the owners best interest. AFAIK, Mike won't take an RV on as a managed airplane, but if you are persuasive, maybe he would do a one time deal to work with you and a mechanic so this could be sorted out. He's a pro and by reading and listening to much of his work, I know he loves a good challenge. http://www.savvymx.com/
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  #59  
Old 03-18-2012, 09:50 AM
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Bubblehead Bubblehead is offline
 
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Thanks Stan. I may contact Mike but Walt A. is helping me sort it out right now.

Additional actions since last posting:
1) checked compression on all cylinders cold - 1, 2, 4 were >75 BUT 3 was 45!
2) looked in cyl 3 and saw a small amount of oil pooled. Cyl 1, 2, 4 did not show that. Makes me suspect rings
3) started engine and it ran rough but I think I over-primed it. Once it cleared out it ran smooth and everything looked normal.
4) shut it down and did a warm-cylinder compression check. ALL CYLINDERS now tested >75 including #3
5) Yesterday we did a cold compression check on #3 and it was 72 - a little low. We also removed the valve springs and checked the valve guides in cylinder #3 and they were fine. The valves operated smoothly. Also checked dry lifter valve clearance - also ok.

Two possible paths:
1) Fly locally to try and get the condition to repeat itself and record all the data. I love my SkyView but unfortunately it does not have a data recording feature right now.

2) I think the problem is one or more bad rings in #3 and may pull the cylinder next weekend and take it to a shop for a thorough check.
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Last edited by Mike S : 03-18-2012 at 09:58 AM.
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  #60  
Old 03-18-2012, 02:57 PM
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NickAir NickAir is offline
 
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Default #3 cylinder compression

#3 w/ cold compression at 45psi is grounds for further inspection if it does repeat a second test at near 45psi (cold) after operated to operating temp.

There are cases of low compression readings that are misleading, when cold, due to good and serviceable rings being in alignment. This is rare, but proven to happen. Point is there should be a second, cold compression test performed to clarify this issue. Also, a small grain of carbon deposits can cause the same if on the valve seat. To check, remove the valve cover and with a rubber mallet strike squarely on top of the valves which will crush any deposited preventing a good seal of the valves.

You may have heard and/or done these tests. If so, just disregard.
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