One of our 150 has a sticking valve for the second time thus year. This seems to be a reoccurring problem. One stuck last year and the year before that two had to be replaced due cracking after 1300 hours.
One of our local maintenance organisation guesses that only about 10% of continental cylinder heads make it to TBO. Whereas the bottom end appears to be maintenance free. Bar low oil pressure when hot and at idle.
We are therefore thinking that in the future we will replace all 4 cylinder heads at say 1100 hours and then send the removed ones for overhaul.
Does anyone have any expirence of doing this. Also does anyone have any opinion on which cylinder heads are the best conti, EFI or melenium.
Dont tell me that you are using 100LL for this engine ? I once had a C150 that came after a TOH,kept it for 5 years,used 100LL but obeyed the connoiseurs sayings…“heavy leaning even at idle at 1000 RPM minimum” but still I had a sticky valve problem arrising so I converted to 95 Unleaded autogas and solved the problem.
Yes we are using 100LL and as it used for hire and reward we are not allowed to use mogas. On the odd occasion when we visit a airfield that has 91UL we fill it up on that but thats rare.
A good friend of mine but something like 1500 hours on a C150 on UL91 and never experienced any sticking problems – although he did have loss of compression on one cylinder.
But due to regulation we are where we are so swithing to Mogas isn’t an option.
Pitty,because this engine was designed for the now extinct Red 80 Octane fuel. It is silly that those regs oblige you to use an unsuitable fuel as 100LL for this engine.
At least you may explore the possibility to get an STC for autogas,This will solve your problems and not the constant reaming of the valve guides,or even worse to search for alternative cylinders.Dont know if the metallurgy of those alternates makes any difference.
Again Mogas is not an option. One of the aircraft does actaully have a Mogas STC but due regulation we can’t use fuel that doesn’t have the regulatory paper trail. Plus its almost impossible to get Mogas thats ethonal free in the UK as well.
Even if we go back to the 1990’s when 4 Star petrol was available in the UK, which in my opinion was a perfect fuel for O-200 the regulatory body still wouln’t let us use it for flight training.
So basically we are stuck with 100LL as much as a deplore it and feel it makes our operation less safe.
Our C-85 engine in the C140 I had when living in Texas had a sticky valve problem (we too could only get 100LL, and there wasn’t an STC for us for mogas). We started using Avblend every oil change, the valve sticking problems went away when we did that. Of course a sample size of 1 is hardly data.
It was intake valves that would stick in ours, which leads to the engine just quitting cold as the other cylinders no longer get a proper fuel air mixture once the valve sticks.