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High oil consumption on an IO-540

rotoiti

Well Known Member
My RV-10 has an old engine (about 5,000 hours on it). It was top overhauled before installing in the -10, and it had installed all new, nickel cylinders at that time.

The oil consumption was always high but during 4 years (and 300 hours) I owned the airplane, the consumption increased from 1 quart per 3.5 hours to 2 quarts per 3 hours. Oil analysis shows increased nickel but that is in line with nickel cylinders.

This is still in-spec by Lycoming standards (current consumption 0.66 qt/h vs. 0.87 qt/h maximum) and my mechanic recommends just adding oil. Looking for a second (or third or...) opinion :)

Thanks!
 
High Oil Consumption, Until:

Our -10, ECI (new) Nickel cylinders had high oil consumption (qt every 4 hrs). We "broke in" with mineral oil and switched to Aeroshell after 50 hrs -- oil consumption remained high ----- THEN, we found out that ECI recommended Phillips XC for break-in and permanent use. We switched to the Phillips, and, over time, the oil consumption stabilized at quart every 10-12 hrs. Just a data point, but worked for us.

I use the Phillips on my new (at the time) ECIs on the -6A and certainly have no complaints.

Ron
 
Break-in

If the cylinders weren’t broken in properly, they may never break in no matter how much time they have on them. Assuming valves are good, pull them, crosshatch the cyl, install new rings, then break in properly.
Good luck !!
 
385 hours on the cylinders, since 2012 I believe.

With that high of a oil burn with such low hours on your cylinders I would definitely be pulling the cylinders for inspection. What do your spark plugs look like? How about the inside of your exhaust pipes?

Bill
 
Yes, I have no idea if the cylinders were broken in properly. I bought this airplane when it had 106 hours on it.

Spark plugs look fine, no fouling. I have dual LSE Plasma 3. My mechanic insists on aviation plugs, so that's what is installed there now. Not sure if that could be the reason.

Compression is fine, two cylinders are in 69-70 range, rest is 75-77.
 
Yes, I have no idea if the cylinders were broken in properly. I bought this airplane when it had 106 hours on it.

Spark plugs look fine, no fouling. I have dual LSE Plasma 3. My mechanic insists on aviation plugs, so that's what is installed there now. Not sure if that could be the reason.

Compression is fine, two cylinders are in 69-70 range, rest is 75-77.

I’d get a second opinion on mechanics.
 
I’d get a second opinion on mechanics.

+1 on Jerry’s comment. While I agree this has nothing to do with your excessive oil burn, use the recommended plug. If your mechanic does not understand electronic ignitions, don’t let him work them.

Just to make sure - I assume you are not filling up the sump to 12 qts. Most people run around 8 or 9 qts. Anymore will just blow out the crankcase vent.

Carl
 
Yes, I tried running it with 9 quarts, 8, 7 and 6 quarts respectively for about 10 hour periods each. The consumption was pretty much the same. I never flew with more than 10 qts.

Re: mechanic. He's a good guy, A&P with IA who has been working on my airplane for 4 years since I bought it. He is convinced magnetos are more reliable than electronic ignition. If you have a recommendation around SF Bay Area for a mechanic familiar with IO-540 and not afraid of working on "experimentals", then I am all ears. As I said, I want to get a second opinion.
 
I second his opinion

Just my opinion, but I agree with your current mechanic about running mags on a 540.

It would be unwise to force a technology foreign to the dentist you have a relationship with that is actually working inside your mouth....

Some people have great reports with various EI systems. I am not one of them. In the mountains and over water I will carry on with mags.

A good A&P friend has an R22 with an O 360 about 200 hours since a pro shop did a 2000 hour on a first run engine. His compressions are 78/80 and better. 2 of the cylinders are 80/80. He still has an abnormal high oil consumption. Higher than before it went for rebuild. I suspect the valve guides are responsible in his case.

Do you have a plain breather system? or a positive evacuation (suction) system for a breather?

Tom Martin did some manometer pressure testing of the exit cowl of Rockets. He found that about 2" aft of the bottom edge of the fibreglass cowl exit, was the lowest pressure. That is where he positioned his breather tube exit. If your rings are OK.. and IFF the oil is going between the valve stems and guides , having some negative pressure in the crankcase might help... but perhaps tough to overcome the suction in the intake tubes and ports where the valve guides terminate.

Perhaps check the oil return lines are good and clear from the rocker boxes. It would only take 1 out of 6 to be restricted or blocked and the consumption would go up.
 
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This engine has a regular breather.

I have talked with the mechanic and raised the concern again. He is going to check the valve guides. He is also going to look at the piston heads for discoloration with borescope. I will update this thread when I know more.
 
oil consumption

My O-540 got a new engine a few years ago. It only uses 1-2 QTs per 25 hour.
I was careful to do the break in with no wasted idle time. I think break-in is really important to get those rings burned into the cylinder walls. The first hour is especially important for the ring burn in. I did first 10 hours of breakin with 100% mineral oil by Phillips 100 weight. Then I ran 20W-50 Phillips XC which has no additives so I also add one bottle of CamGuard.

Your high oil consumption sounds like a good break in didn't happen after the top end. Perhaps the owner then didn't know a top-end overhaul needs a break in just like an all new or rebuilt.

I second the idea of getting second opinion from another A&P/AI. You are probably close to a major overhaul.
 
I change oil every 25 hours.

I just dropped the airplane at the shop. They did a compression check and apparently cylinders 2, 4 and 6 have compression values in high 40s :-O During annual in June, they had 67-70. I am highly surprised.
 
I change oil every 25 hours.

I just dropped the airplane at the shop. They did a compression check and apparently cylinders 2, 4 and 6 have compression values in high 40s :-O During annual in June, they had 67-70. I am highly surprised.

While it is unfortunate for you, it is a good lesson for others. Don't ignore it when your engine is talking to you. relatively rapid increases in oil consumption means that something is happening and it usually isn't good.

Please let us know the final diagnosis.

I also would look for another mechanic. First, he should have been concerned with the significant increase in oil consumption. Second, 1 qt in 1.5 hours is a strong indicator for pulling a couple jugs to see what is going on. Advising you to ignore the symptoms and just throw more oil at it, is bad advise in my opinion. The cause may be something that you can ignore and address with oil and it may not. However, not knowing the cause means you are taking unnecessary risk.

Larry
 
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Food for thought!

? We build, modify and test a lot of engines at our facility, and thought our
testing procedures could be of interest to some reading this thread. The leak
down test, that is commonly referred to as a compression test in the aviation
community, really doesn't provide much of the true picture of cylinder health.
Firstly it only addresses what is happening at the very top of the stroke, and
then only the compression ring. Its very possible that one or two inches down
the bore a completely different scenario exists. Cylinder taper, galling, pin
button damage Etc. can be happening and the leak down numbers can be
perfect. After performing the standard test, while the top plugs are out get an
automotive type compression tester and do a cranking compression test as well.
This will or can expose some possible other problems, and you can't have
too much information. High oil consumption can many times be attributed
to a stuck or broken oil ring or wiper ring, that will not show up on either of
the compression tests. Always do a cranking test as well. It only takes a couple
of minutes and can provide considerably more information. Thanks, Allan...:D
 
A good borescope, spark plug and ex pipe inspection along with leakdown and Allen?s suggested compression test may indicate only 1 or 2 cylinders need to be pulled. Glazed cylinders is seen as brown patches on the cyl walls.
If its only 3.5 hrs/qt. and all other tests are negative it will be hard to know whether to run it or do surgery. Certainly increasing oil usage is indicator to pay attention to.
Good luck
Tim Andres
 
I decided to pull all three suspect cylinders (2, 4 and 6). They have been sent to a shop. I'll update when I get more info.

@bobnoffs: yes, same shop.
 
Also, looking back on my original post, I realized that I may have misrepresented what the mechanic was saying.

My mechanic's suggestion of "just adding oil" was based on oil consumption of qt/3h which was pretty stable over ~3 years. The moment I reported sharply increased oil consumption he suggested checking the cylinders.
 
Unfortunately for me, things are not looking good:

All cylinders are nickel bore and the cylinder walls are wavy with a ring ridge.

One of the cylinders has a crack in the cylinder head next to the exhaust valve seat.

All three exhaust valves rejected due to excessive wear on the stem.

One intake valve rejected due to pitting on the face.

All exhaust valve guides are worn beyond limits.

One piston is damaged from detonation.

I think I'll ask them to pull the remaining cylinders to check for damage.
 
Cylinders

I may have missed this but who made the cylinders? ECI, Superior, Lycoming, Continental, etc?
 
Lycon, I think, manufactured the high compression pistons and maybe cylinders as well. I am not sure and the documentation is sparse.

At this point I am thinking of just doing a complete overhaul for safety.
 
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