OS FT 160 Four Cycle Twin has sticky valves
07-19-2004, 12:57 PM
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OS FT 160 Four Cycle Twin has sticky valves
I use after run oil (Marvel) but after 2yrs of not running this engine, a test spin of the prop revealed-no compression at all on either cylinder! One or both valves on both cylinders were jammed open. I took the engine off the airplane and begin dousing the cylinder head and pushrod tubes with air tool oil. After spinning the prop many times, I was able to free up the valves and then I test flew the airplane. What I found was very degraded performance from the engine. I'm used to short takeoffs and loops from level flight with my scale biplane but it could now barely get off the ground.
This OS has always been a great engine with alot of power, does anyone know how I can fix this sticky/leaky valve(s) problem?
Thanks, Jim.
This OS has always been a great engine with alot of power, does anyone know how I can fix this sticky/leaky valve(s) problem?
Thanks, Jim.
07-19-2004, 06:16 PM
#2
RE: OS FT 160 Four Cycle Twin has sticky valves
I have an OS 240 twin and have experienced similar problems when letting it sit for an extended period. I found that the problem was not the valves but the lifters. I removed the valve covers and sprayed oil (I used WD40) into the pushrod tubes and then worked the rockers to push the lifters back down while turning the prop. After a few minutes of doing this the lifters loosened up. I re-installed the valve covers and started the engine. The engine appeared to run normally although I haven't flown it yet (Ohio RC 28% Ultimate).
George
George
07-19-2004, 08:37 PM
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RE: OS FT 160 Four Cycle Twin has sticky valves
That's a big affirmative on the sticking lifters. But I prefer keeping WD-40 as far away from my engines as I can. Mix some ATF 50/50 with either acetone or ketone, suck it into the crankcase breather port. Get a good amount in, then turn the engine upright and just roll it. This wall bathe the cam and lifters, free everything up. when it's all working nicely, either leave the mix in the engine until you're ready to fly it, or dump it, add a little fresh after run oil, and go fly immediately.
Bill.
Bill.
07-20-2004, 07:35 AM
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RE: OS FT 160 Four Cycle Twin has sticky valves
WD 40 works well to free up a sticky engine IF (and that's a big "if") you run it right after applying the WD40. If you let the engine sit with WD40 in it it will gum up worse than before (ask me how I know, LOL.......)
