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DIY Honing?

71459

Well Known Member
A question for Lycoming engine gurus.. I want to have one cylinder on my Lyc O-320 honed and new rings fitted, no other work performed. Is this something a person can do themselves, or is an engine shop absolutely needed for this work? - Thanks
 
I honed some cylinders at home one time. It seemed to work but it was a messy job. I did not remove the valves. See posts #40 and 41 here
http://forum.canardaviation.com/showthread.php?t=4923&highlight=hone+cylinders&page=3

Kent thank you for the information. My cylinder looks very much the same as yours did (see attached borescope pictures), and it only has 300 hours use since this was last done by a pro shop. I'm very disappointed in that and want to explore whether I can do a better job myself (and cheaper).

Compression is not bad 76/80, oil consumption is 10 hrs/qt, but the oil gets black pretty fast and I can hear a hiss out of the oil filler when this cylinder is under compression.

Can you say which abrasive you used for the job?

Piston is at BDC. Nasty score running vertically along cylinder wall.
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I'm no expert, but the honing job looks terrible to me.
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This is at the top of the piston travel and is where I find the worst of the scoring.
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I'm certainly no expert but in the past my cylinders always had a very distinctive cross-hatch pattern - that I don't see in yours.
 
I'm certainly no expert but in the past my cylinders always had a very distinctive cross-hatch pattern - that I don't see in yours.

Right - the crosshatch is there.. the pictures make it look a little odd with the bright, glaring light. To me the honing is much too deep and aggressive. But it might be acceptable and not actually have contributed much to the "failure".

I am thinking that honing is definitely in order - the vertical scoring needs to be removed.
 
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honing

I used a 120 grit ball hone and have honed a cylinder and replaced the rings.
Hard to do single handed and operate a drill and squirt honing oil at the same time. I had one cylinder that got too hot too lean and melted about half inch of upper ring groove enough that ring was locked down, blew the crank seal too. New piston, rings and honeing the cylinder fixed that. A little more carefull about leaning too aggressive. And 91 mogas. These were ECI steel cylinders, narrow deck o320 on an RV7. PS have overhauled this engine and lots of other car, tractor, lawnmower etc. engines.
A cylinder shop can do the job too!


1 quart oil consumption in 17 hours.

Keith Rhea
RV7
 
A cylinder shop can do the job too!

Keith Rhea
RV7

Thank you Keith. This cylinder if from a local shop and I just didn't come away with a good feeling about the quality of their work. I don't want to go though wasting time and money like that again, so I figured I'd do it myself.
 
I have a Sunnen AN portable hone that I use for fixing ring step wear and roundness and use a variety of stones. For just cleaning up a cylinder I use a Brush Research aluminum oxide 320 grit ball hone. I have a plastic disk I place at the bottom of the cylinder which keeps the tip of the hone from scratching the head. I use lard (yes vegetable shortening) which is water soluble and not as messy so I can wash the cylinder in a sink after honing. I use a bore brush for washing.
 
I have a Sunnen AN portable hone that I use for fixing ring step wear and roundness and use a variety of stones. For just cleaning up a cylinder I use a Brush Research aluminum oxide 320 grit ball hone. I have a plastic disk I place at the bottom of the cylinder which keeps the tip of the hone from scratching the head. I use lard (yes vegetable shortening) which is water soluble and not as messy so I can wash the cylinder in a sink after honing. I use a bore brush for washing.

Thank you Bob - I appreciate the input. I have been reading through the Lycoming Overhaul and Service documents.. I believe I can accomplish this, save some money, and learn a new skill at the same time.
 
I have honed lyc cylinders myself with good success. I believe that I used 220 grit stones on a typical three leg honing tool. The key is to insure that your are getting deep enough in on each stroke (without hitting and breaking the stones) and that you establish a stroke rhythm that matches the drill speed to get the cross hatch angles close to the spec. Those angles are important to minimize oil consumption and/or avoid irregular wear.

A second pass with 400 grit stones would reduce the break in time.

Ball hones should work well also, though I haven't used them.

Larry
 
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Compression is not bad 76/80, oil consumption is 10 hrs/qt, but the oil gets black pretty fast and I can hear a hiss out of the oil filler when this cylinder is under compression.

With 76/80 and 10 hrs/qt, as well as the possibility of upsetting bearings during cylinder work (read Mike Busch!), I think I would live with them a bit longer.

No expert here but your hone job looks very coarse. Lycoming S.I. No. 1047B recommends medium grit stones on a three-leg hone. The Brush ball hone I used is at the airport but my problem was mainly polished cylinder walls that had lost their hone pattern and had some vertical scratching. (I suspect my overhauler did not get all the grit out of the cylinders).

Your hiss might be air leaking through ring gaps. Black oil might be from running too rich. Maybe let sleeping dogs lie. :)
 
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Maybe let sleeping dogs lie. :)

Kent, yes that has occurred to me as well. The cylinder condition is not "prefect" but it's a mid-time engine and it might be best to just leave it alone and live with it. My main consideration here is safety. As long as this cylinder is safe to operate, it might be best to live with it for now.

PS it certainly is a frustrating result after already paying a professional engine shop too much for this cylinder.:mad:
 
what borescope are you using? My guess is the camera is making it look way worse than it actually is. It appears to be magnified quite a bit.

Being able to run that many hrs per Qt of oil doesn't make the case for pulling a jug....Yet.
 
what borescope are you using? My guess is the camera is making it look way worse than it actually is. It appears to be magnified quite a bit.

These were taken with the Vividia VA-400 scope, my first time using it. You are right - at certain angles with the bright LED reflection it looks worse than it actually is. I find it kind of difficult to get a good, sharp picture. I can see it takes some practice.

But it doesn't look like the initial honing has been smoothed off much. I wouldn't be surprised if they gave me the wrong rings.
 
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The angle of the cross hatch is non-standard, typically it is 45 deg. And it does look a little deep. My inspection has some vertical scratches too, I dont know why, but the oil analysis for mine looks good.

You might send a good oil sample in for analysis to see what it yields. It can be a good diagnostic tool with the right experience applied.

I say good, as have the oil hot and stirred, then catch some during a drain a few seconds after the stream begins, not initial and not late. Just sample for the natural drain stream.
 
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