Sticking Exhaust Valves

[Kevin Hynes]

Any body out there having any problems with exhaust valves sticking? Newer Lycoming (most 360 series) engines seem to be prone to it, older ones not. I never had a problem until flying the newer ships. Seems to be evident right after start up. I have been starting and idling at 1000RPM until oil pressure indicates in the green, then run-up to 2000RPM until oil and cylinder temps are in the green. If it sticks, it seems to do it in the first 30 seconds, at which time the ship can be shut down. Usually on restart it will be free and okay. Oil change intervals at 20-25 hours (earlier the better) seem to help. First problem occurred around 300 since new, three seperate occasions, three seperate valves. Using Aeroshell 15W50, will try 100W Plus this summer. Let me know.

[9121u]

Good Topic Kevin I Have Heard Of That Before My Brother That Ownes N5913X Told Me His Mechanic Said Too Use Marvil Mystery Oil In The Gas Just A LITTLE BIT iT Says On Bottle You Can Use In The Oil BUT I Would Not Put Any In OIL What Do You Think About That Also Mine Is A B2 Ever Hear Of Carb Ice Up In A B2 I Havent Had No Problems Was Do You Think I Have To Watch For It . HAPPY FLYING

[Kevin Hynes]

Thanks for the heads up on Marvel Mystery Oil, I have heard of that along with AvBlend? an additive recommended by Lycoming. Supposedly the Aeroshell 15W50 and 100 Plus have the recommended additive to help, but to date have not seen any difference.
Carb Icing, for both B-2's and B-2A's CAN be a potential problem. I have had occasion to use the carb heat on a regular basis to keep the Carb Air temp in right range and ward off loss of performance for what was probably carb ice. Remember typical techniques for riddinng the engine of suspected carb ice. Probably best to do when on the ground (rather than in flight). If full carb heat is applied, the engine is going to be running rich, so it may have to be leaned slightly. PLUS, if ice was present, the melting ice/water is going to be ingested, also resulting in a power change (usually very short lived, but be expecting it). Setting the Carb Heat during a hover will allow you to also lean for best power at that high power setting, rest of flight the power setting will be lower and mixture should be alright for the next approach or hover work. Any one else got thoughts or experiences? Talk with you later Kevin

[Del Dammann]

I had what I thought was sticking valve on startup. It happened after a top O/H and cam and valve train replacement. when the engine is cold the oil pressure goes quite high, could be well over
100 lbs. , I measured mine at the oil galley at the front of the engine. the high oil pressure pumps up the lifter and holds the valve open until the oil warms and the pressure drops back down.
The gauge in the dash is not accurate because of the long cap tube from the engine so it will not tell you of the big spike in pressure. using lighter oil or preheating the engine will help.
It is possible to change the lifter without removing the engine but this would my last resort. this problem happens sometimes after replacing the oil pump for the AD. The new pump would have more output and could cause the pressure spike without raising the running pressure after warmup. Try lighter oil or preheating the engine, if that stops the problem, you don't have a sticking valve.

[N2285U]

I use 4 ounces of Marvel mystery oil for every 10 gallons of gas and I can tell you my injectors and valves look like they just came out of the factory, nice and shinny.

[donlew]

Where do you get the mystery oil? I may have this problem of sticking valves in my ship.

[9121u]

You Can Buy It At A Parts Store. Comes IN Quart Bottle I Buy Mine At Trader Horne. I Dont Use Every Tank About Once Every Three Tankes. You Are Not Suppost Too Use Any Additives In AVE GAS But I Do.