Mogas problem.....

[astjp2]

Here is a pic from a C-172 where the carb dripped auto fuel onto a brand new tire, notice how the tire bulged and the tread swelled. I wound up replacing the tire. Needless to say the owner was PISSED! This is just an FYI for those of you like me that use mogas. Tim

[flyguy]

Re: Mogas problem.....

I know this should not be a question, but was that with or without ethanol? I had to ask. What state?
DC

[astjp2]

Re: Mogas problem.....

Ogden UT, and I didnt test for Alcohol, I dont think they use it because of the altitude...4500 msl

[3Dreaming]

Re: Mogas problem.....

Avgas will do that as well. Given time it will shrink back down, but I would replace it too. Tom

[fearofpavement]

Re: Mogas problem.....

You sure that's from the fuel? With the degree of distortion makes me wonder if the tire may be defective. (such as a ply separation)...

[astjp2]

Re: Mogas problem.....

Its from the gas, it was dripping out of the carb air box and the tire went soft and swelled where it got fuel on it. It sat for a week with the fuel off and was still swelled pretty bad. Tim

[crispy critter]

Re: Mogas problem.....

How long and how much gas leaked on the tire?Also,as Tom said,100LL will do the same thing only it will do it quicker.....fix the fuel leak and you will not have that problem. I admitt that if you have an airplane that only flies a few hours a year it is better to have 100LL in the tanks because it will not go stale or varnish.However if he's running an 0300 cont and flying it regular he will much rather pay the price for a tire over the cost of cylinders,fouled plus,burnt or sticky valves,and lead build up. We have a C-170B with an 0300A that runs mostly on 100LL and in the last 300 hours over the past 4 years we have pulled 4 cylinders because of lead build up on the valves and one burnt valve. In the other hanger we have a 1959 C-172 with almost 700smoh that was done in 1997. It rarely gets any 100LL(almost always 87oct) and has never fouled a plug,never had a cylinder problem,and runs twice as good as the C-170.The plugs from the C-172 are always clean and the oil filter never shows any carbon,dirt,or sludge what so ever between 50 hour changes. The C-170 with the same oil filter system always has dirty,black oil,lots of carbon,and the plugs are always carboned over after 50 hours. Do your research,these old low compression continentals were designed for 73-80 octane leaded or unleaded gas. Way back then when they said leaded it was much less then today 100LL.....less by almost 4 TIMES what they used back in the 1940's,50's,& 60's. That's right,todays 100LL has nearly 4 times the lead that was available back in the day when these engine were built.
P.S. I don't mean to offend you by saying this but tell your client to keep running auto gas or you will be making a lot more money off of him in the future doing cylinder repairs....just my humble opinion.

[Len Petterson]

Re: Mogas problem.....

My "new" used engine has never seen mogas and has a considreable amont of lead on the valvesteams after 600 hr on leaded gas 87 and 100LL.
It was preseverd for 10 years . It shall be interesting to see how it does on mogas.
Len

[jstall]

Re: Mogas problem.....

I use mogas in both the Cessna 190 and the Cart, not a steady diet of either, kinda alternate it or best yet mix at about 3 to 1, mogas to 100LL
I think that is what Peterson recomends, maybe 2:1, anyway that will approximate the correct amount of lead as was with the original 80/87
avgas

JS

[birdlegs]

Re: Mogas problem.....

I noticed the gascolator "o" rings would swell out of shape and leak from the valve, as I use mostly mogas. The "o" rings just got replaced more often and were cheap neoprene, If you can find the viton type they last longer but need more spring pressure so old soft springs need replaced.

[Len Petterson]

Re: Mogas problem.....

O-rings is a science of it own!
Standard Orings are made from Buna-n but can be had in almost any rubbber type your hart desire. If you want to pay for it.
Swagelock, a fitting manefacturer with a listing of suitable materials for varius chemicals, list for gasoline:viton and delrin as best and buna N as fair with limeted life, Neoprene and Nylon as Unsatesfactory.
O-rings from Viton are grey or black with a white dot. Contact your local hydrualic supplyer if you cant get them elsewhere.
For alcohol : best is Buna-N Viton,neoprene, delrin.
There is a caution note on the bottom of the page: use this corrosion chart with caution.
It has not been far off before in my experience.
Len

[3Dreaming]

Re: Mogas problem.....

I noticed the gascolator "o" rings would swell out of shape and leak from the valve, as I use mostly mogas. The "o" rings just got replaced more often and were cheap neoprene, If you can find the viton type they last longer but need more spring pressure so old soft springs need replaced.

If you are talking about the quick drain make sure it is not supposed to have a special seal. The Curtis drain valves use special seal, and not a O-ring. Tom

[Guest]

Re: Mogas problem.....

CAUTION - OPINIONATED MESSAGE FOLLOWS

The manufacturer of Curtis drain valves explicitly states that the seals are not replaceable, the valves are not repairable.

Since the manufacturer states that then if one replaces the seals they are operating outside of approved data and outside of airworthiness constraints for the appliance.

It really doesn't matter what our opinion is about this or if we can find a pma part somewhere all that matters is what the manufacturer states about his product.

I replace the entire valve (about $12 at Wicks and others), its not worth a $10 savings every 5 years (or even if it was once a year) to me and I don't like the thought of those valves ever failing open in flight because of the seals popping off. Of course if/when that does happen and an invetigation follows then Curtis will respond that the valves were not supposed to be repaired/replaced and one will be hosed from a legal point of view.

[Forrest Barber]

Re: Mogas problem.....

AGAIN they are not a "O" ring they are a "flat packing" many valves use them. Curtis used to sell them , then they say no repair and they do sell them. The seal a "flat packing" costs almost as much as a new unit. replaced two this past weeek-end on Piper Cherokee & a Warrior.

[Guest]

Re: Mogas problem.....

AGAIN they are not a "O" ring they are a "flat packing" many valves use them. Curtis used to sell them , then they say no repair and they do sell them. The seal a "flat packing" costs almost as much as a new unit. replaced two this past weeek-end on Piper Cherokee & a Warrior.

Whatever they are packing or o-ring they say no repair as you mention above.