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Oil Ring Flush

Manchu16

Active Member
Over the past 30 hrs or so I have watched my oil consumption climb. I have been addressing a bunch of squawks from when I bought her.

I usually saw 1qt per 6 to 7 hrs fast forward and now I am 1 qt per 2.5 to 3 hrs. I put a brasso can on the bottom of the breather and I am definitely pushing a bunch out. The belly confirms it. Overall the slight leaks on the engine, have not changed and the inside of the cowl is dry. I normally run at 6 and fill at 5 qt. I let her go to 3 qt and no change on the rate of burn.

Borescope and compression tests look great. Both hot and cold compressions are where they were for the past 2 CIs. Oil analysis is enroute to Blackstone. Plugs are clean.

Savvy looked at then engine data and nothing noted. The tech proposed an oil ring flush.

Having never done one, nor has my A&P, I wanted to see if is as straight forward as the instructions provided and if there is any downside. I know I need to pull my quick drain, but I was doing that anyways to replace the orings.
 
It is very easy to do and really no downside. I started burning a bit more oil than I had in the past 12 hours/qt to 6 hours/qt. I did the ring flush and was not able to really clear two cylinders on the first try. The next oil change I was able to clear those two cylinders and my oil consumption has improved to 1qt/ 10 hours. All the ingredients are available at the big box stores.
 
I have an RV-6A 0-360 channel chrome cylinders cs prop 550 hours converted to SDS fuel and ignition burning Costco Premium. usual flight regime is 2200 at 26 inches or full throttle above 4500??
Oil burn was 1-5 hours with Areo shell 20x50.
two cylinders cleared fine, one was about 80 percent good. fourth was a NO GO period.
worked on the bad cylinder for 5 times still no go. third cylinder got a little better.
Put same oil back in and flew for 5 hours like I stole it.
Pulled cowl and repeat both bad cylinders, third cylinder improved a bit. the fourth one actually flowed about 20 percent.
Changed oil and filter and added 6 1/2 of Phillips blue bottle 20x50 XP
Just changed oil again at 25 hours and was at 1-6 hours. I did the flush on the bad cylinders and the third cylinder was better than before and the #4 cylinder flowed about 50% of the others.
Oil analysis came back with much improvement in all factors and they said keep doing what ever I was doing cause it is of great help.
Now did I reduce oil consumption??? Not really as far as I can see.
But if you don't get the solvent solution to flow past the rings. keep trying as you have nothing to loose in my humble opinion.
I got a sore belly hanging on the prop trying to get my #4 cylinder to flow.
I'm kinda screwed on trying to get oil consumption less because of the channel chrome cylinders
My luck may not be as good as yours. Art
 
If a cyl stays in hydraulic lock, hang some weight from the prop and go home. I’ve seen very stubborn ones but never one that didn’t eventually flush. YMMY
 
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I did a ring flush recently with Seafoam and the owner of the airplane says there's a good improvement in oil consumption. On the cylinders that dont flow I fill them to soak overnight.
 
The ring flush is mostly to clean out the oil rings. I did it to clean out hte compression rings and it seem to help just a bit on my compressions, but no miracle. I have not had a chance to run the tests again after getting some run time on the cleaned ring lands.

When oil rings get fouled with carbon deposits, it can cause them to loose some effectiveness and this leaves more oil on the cyl walls than desired and this oil burns. So, if you believe that the consumption is due to burning oil, then the ring flush is a great idea. The other way that engines loose oil is as tiny particles being pushed out of the breather with the air. If you think that excessive blow by may be the cause for for the perceived consumption (kind of implied if the separator is making a lot of oil product), I don't believe that the ring flush will help a lot. Worth trying, as I did, but speculate it won't help a lot. A static compression test (what aviation uses) is not the best tool to determine blowby, as it only measures the rings effectiveness at one position on the cyl wall and blowby occurs for a decent amount of travel up and down the cyl. A dynamic compression test may be more telling. You are not really looking at total compression (no good reference data, as no one uses it), but give very good relative data to find weakness from one cyl to the other.

One test for oil burn (i.e. poor oil ring contol) is to let the engine idle for 10 minutes and shut down without increasing RPM. Then pull the plugs and look for wet oil. At idle RPMs, there is not enough heat produced to burn the oil off the plugs and will indicate that too much oil is being left on the walls. If you are lossing a qt in 2 hours due to poor oil ring control, this test should show it. If plugs are dry, I suspect that most of the oil is being pushed out of the breather.

Larry
 
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where are you guys getting Xylene and Varsol in CA? are there alternatives that can be used for this process? Thanks.
 
I'm in CA and got xylene from Amazon. Most of the vendors on there won't sell to CA but one did (this was 6 months ago). Varsol as mentioned is akin to mineral spirits or paint thinner/brush cleaner from Home Depot etc.
 
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