Engine Flush

How to keep the Cessna 170 flying and airworthy.

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wa4jr
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Engine Flush

Post by wa4jr »

I am wondering if anyone has any experience adding automotive engine flush to the O-300 just before oil change :?:

I read about using Marvel Mystery Oil in an earlier post. I have always run a quart of "GUNK" or K&W engine flush through my automotive engines prior to oil change just to clean them out real good. I would think adding a quart of flush to the O-300 and letting it idle for five minutes prior to oil change would do wonders for cleaning the trash out of the engine and loosening some buildup around the valves :?
John, 2734C in Summit Point, WV
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GAHorn
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Post by GAHorn »

I know it "thinks" good (I was going to say "sounds good" but that really doesn't express it , ...does it?) to believe your engine is sparkling new-like clean inside,....
But that really isn't a good idea I don't think. You're going to send all sorts of varnish and dirt/things through your engine if you use an aggressive internal cleaner. The dark varnishes/coked oil that is coating all your internal engine parts also helps keep rust and corrosion down. That's one of the reasons the old castor-oils were pretty good for aero-engines, they left a nice protective coating on all the non-moving parts. (The castor oil just couldn't handle the longer oil-change periods and higher temps.)
acroav8r
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Post by acroav8r »

Ihave used 5 minute motor flush in aircraft engines and have found no ill effect and after a few oil changes using it my oild did stay clean a lot longer after it was changed. As dirty as these engines get inside and the varnish that collects i=on the exhaust valve stems causing them to stick it just seems like a good idea. I also use avblend and it appears to keep the inside of the engine a lot cleaner. Can'y say for sure if keeping it cleaner inside help but it sure seems like it should be better for the engine. Isn't that why we put oil filters on our engines ???
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c170b53
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Post by c170b53 »

I thought that the aviation oils were non-detergent type oils. On opening up a case there's a film of grey goo everywhere.
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GAHorn
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Post by GAHorn »

acroav8r wrote:Ihave used 5 minute motor flush in aircraft engines and have found no ill effect and after a few oil changes using it my oild did stay clean a lot longer after it was changed. As dirty as these engines get inside and the varnish that collects i=on the exhaust valve stems causing them to stick it just seems like a good idea. I also use avblend and it appears to keep the inside of the engine a lot cleaner. Can'y say for sure if keeping it cleaner inside help but it sure seems like it should be better for the engine. Isn't that why we put oil filters on our engines ???
"and it appears to keep the inside of the engine a lot cleaner..." --Cleaner than what? What "control" do you have in this experiment?
As for automotive cleaners.....once again, automotive stuff simply isn't approved for aircraft use. Not to say they don't sometimes have appropriate uses, but I don't subscribe to "flushing" out engines by runnning them with automotive cleaners in them. Where do you think all that stuff goes when you break it loose and send it throughout your engine? Isn't THAT why you have been filtering the oil all this time?....to keep that stuff from going all through your engine? Haven't you just defeated the purpose of your filter when you did that?
Keep in mind, that coatings left upon engine parts are protective in nature, ....not detrimental. (And to reply to the next questioner...no aviation oils are NOT detergent. They are "dispersant". They don't scrub you engine internally. They keep combustion byproducts suspended until the next oil change when they are drained out with the old oil. You don't want the protective coatings washed off your internal parts. That would expose them to humid air and rust.)
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