I've done about 500 hours so far this year in the Cessna 150. In this time we have had two spark plug failures and one sticking valve. The o-200 was originally designed to run on fuel with a lot less lead content then what is present in 100LL
One of my mates has put about 750 hours on his 150 in the same time period and something like 1250 all of it on UL91. In that time period he hasn't had a single plug fouling episode or failure. Its also very obvious that the oil is staying clearer longer on the unleaded fuel.
Now I agree a sample size of one is hardly scientific but does anyone else think that all this lead is doing more harm than good.
I should add that my aircraft is leaned as lean can be on the ground. Full rich during climbs to 3000 feet. Leaned to max rpm in climbs above 3000 feet. And leaned as lean can be in the cruise with approx 58% power set.
I have heard the same thing from my colleagues at the flying club, who has been around longer than me. Since we switched to 91/96UL (our Swedish unleaded 100LL alternative from Hjelmco) we have had fewer problems, as you mention. I've been flying there since 2004.. don't have any hard statistics though ..
This is with IO-360 engines in PA28 Archers and C172s
No way I'd run an engine on 100LL that can also run on Mogas. My C172M is doing much better since I switched, better compression, cleaner oil and less residue in the cylinder. 100LL is ancient nasty stuff, very bad for the environment and it shouldn't be allowed on engines that can run on unleaded.
100LL is ancient nasty stuff, very bad for the environment and it shouldn't be allowed on engines that can run on unleaded.
What a refreshing comment.
Thumbs up. Seriously!
In terms of safety of flight, the storage issues with modern auto fuel outweigh the plug fouling issue for those who aren't flying 500 hrs in six months :-)
80/87 Octane AVGAS was good stuff.
Yes, lead is bad, but it is not like we are flying millions of little airplanes up and down densely populated city streets. Compare with cars running on heavily leaded petrol during the 80'es.
Bathman, you seem to suggest that your sticking valve could be caused by running on 100LL. Is that a recognised risk from using leaded fuel instead of unleaded? I am asking openly here, I am definitely no expert.
I've no idea if sticking valves are related to the large amount of lead in 100LL. Although I'm pretty sure o-200 are quite prone to it. The only other o-200 that I've personally been involved in that also had a sticking valve was also running on 100LL but this was some 20 years ago. I've never known a o-200 that's been running on mogas suffer the same problem.
I am certain however that spark plug fooling and the discoloration on oil is alot worse when run on 100LL.
I would like to here from someone who strips these engines to see if they can tell a difference inengines that have been run on 100LL compared to Unleaded fuels.
Valves get stuck because something gets between the valve stem and the valve guide. That something is residue from the combustion process. The main residue of avgas is the lead.
Look at the Rotax engines. When run on 100LL, you need to replace the oil and filter twice as often. There's a reason.
Yes, lead is bad, but it is not like we are flying millions of little airplanes up and down densely populated city streets.
That means you have the right to pollute the environment but 99% of the population doesn't? You can burn your car tyres in the garden because nobody else does it and thus the environment is not harmed on a global scale?
I personally do have a problem burning avgas. It is bad stuff and should be ousted.
We had sticking valve problems which were presumed to be a consequence of having to run 100LL in a C85 engines. Not fun when you've just taken off and all the remaining runway is behind you. We ended up using an oil additive which seemed to make the problems go away. But the sooner that 100LL is gone, the better. It's bad for our engine, it's bad for our health. Our current engine (O-320-B) has now been approved by Lycoming for 91UL, trouble is I don't know anywhere that sells it.
There are a few measures you can take to minimise lead fouling in addition to proper leaning.
Decalin or TCP, if you can find it, will make the lead form as a salt that will get blown off in normal use.
Fine wire plugs or modified electrode types such as the REM37BY are less prone to fouling and may also help. You may also be able to go 1 grade hotter on the plugs if it's within the permitted range for your aircraft/engine.
But unleaded fuel would solve the problem completely. Maybe one day........