1956 - 365 c.i.d. - pushrods destroyed

[Chopper1942]

If the gas is really old, it leaves a sticky residue on conponents. All valves have some "carbon" pm them and with old fuel mixed with the carbon, the valve could stick in the guide.

I've had this happen on a Honda generator that sat for several years. When I went to start it, it had no compression. I took the head off and  found a valve was stuck partially open. The engine is a flathead so there was no damage.

[V63]

This is a very common problem with older vehicles.

The biggest issue is alcohol blended fuels, first the fuel chemically degrades faster...often in 6 months. Interesting  Diluting it does not work past a certain point because the old gas is is heavier and the new gas will rest on the top.

I have observed the vehicle victim will run on the old gas (often you can hear a sticking valve in the exhaust) but it is after it cools again that the valves seize (stick) permanently in the guides so at a later start up some  cylinders will have no compression. This also causes valve train issues. The seizure can be quite strong that even hammering the valve won't budge it.

There is a distinct odor to the fuel once it's degraded.

This effectively has similar effect as the old trick of sugar in the gas.

The fix is generally removing the heads for a full head service. 

[Chopper1942]

Ethanol has a lower vaporization point than gasoline.  Therefore, as an ethanol blend sits and ages in a fuel tank, the ethanol will vaporize off first.  Without getting into a lot of fuel chemistry, the high ends in a gasoline fuel is a blend of many isotopes that have different vaporization points.  That is the differece between winter and summer blends. The winter blends have more high ends so the fuel will vaporize easily at lower temperatures and the engine can start. In the summer blends, the high ends for easy cold starts are removed to lower emissions and prevent detonation.

Any gasoline, whether an ethanol blend or not, when left sitting for an extended time basically is trying to revert back to a crude oil.  It becomes thicker, sticker, and will not easily ignite. I have poured old fuel in a dish and tried to ignite it with a match and it would not burn.

If you have old fuel in your vehicle, do this outside. Drain the fuel system, install fresh fuel, and if the engine starts and runs, get some GM Top Engine Cleaner and with the engine at normal operating temperature, run it through the carb, dripping it in, until you have about 1/5th of the can left. Pour the remaining into the carb to kill the engine.  Let sit for 1/2-1 hour. then take for a drive. It will smoke like the devil and kill all the mosquitoes around, but it will clean off the build-up on the valves and pistons.

[Lexi]

As always, an interesting post Chopper1942. Clay/Lexi

[Ernie and Joy]

I've experienced similar bent pushrods with my Y-blocks, and it sucks. Of course they have solid lifters, so it was absolutely sticking valves after winter storage .  It's a crappy feeling when you fire up the old girl, looking to go for a quick blast around the neighborhood, and wishing 10 seconds your faced with pulling both heads for guide and stem work.
That really, really sucks. I feel your pain

[56Fleetwood]

These responses are very educational- had no idea how ethanol content can cause such serious problems. Thanks to everyone who chimed in!

I guess it's no small coincidence that as of last year I could no longer get ethanol free premium fuel here in Canada, and the bent pushrod problem occurred when I took the car out of storage. I also have a blue oval car that's giving me all sorts of running problems that I now believe is a fuel delivery problem

My only option now is to use Shell V power premium fuel which I believe has less than 10% ethanol.

Would fuel stabilizer in a greater concentration than specified offer any protection from this recurring?

[V63]

I tried stabilizers and despite their claims ... just didn't work.

The alcohol is a catalyst.  not unlike mixing two part epoxy or bondo.. once the two are mixed they are going kick off eventually.

[Ernie and Joy]

Buc'ees sells ethanol free gasoline about 10 miles from me, at 60% more than regular blended.
Oklahoma generally has it everywhere, so I'm lucky, I guess, being that I'm only 25 miles from Oklahoma.

[Chopper1942]

Ethanol is not the issue. All gasoline and diesel will degrade when left unused. If you must leave the vehicle sitting unused for an extended time with fuel in the tank, run the the vehicle until about empty. Park the car. Now, run the engine until it runs out of fuel.

If only for a few months, like over winter, put Sta-Bil 360 in 1-2 gallons of fuel and pour in the tank. This is enough to start the vehicle in the Spring.  Now, fill the tank with fresh fuel. You should not have issues with fuel causing the valves to stick.

You can still have issues with carbon deposits caused by crankcase vapors and oil past the guides. To prevent this run some Top Engine Cleaner through the carb, as per earlier reply, or if FI system, you need to disable the fuel pump, pinch off the return line, and feed the Top Engine Cleaner into the pressure test port with a pressurized canister.

[56Fleetwood]

More great info - thanks. I'm going to use this as part of my storage and start up regimen.

[Lexi]

Parking can be a double edged sword depending especially where you live as well as your parking enviroment. General rule of thumb is to fill your tank, (prefereably without dethanol), use a fuel stablizer, run car then park. This prevents condensation from forming inside the tank. Probably not so much an issue the further south you park your vehicle and/or if your garage is heated. I live in Canada and follow the above noted practice and have not yet experienced a problem. Car can sit for as long as 6 months over the winter down time. That said, wonder if under those circumstances it is a good idea to "bump" the engine every month or so-or turn over very briefly, to keep things loose without starting? Not sure. Clay/Lexi

[V63]

Sorry, Ethanol blends are definitely at issue.

 I had a 'project' of getting an elderly aunts van marketed and sold because she quit driving a solid decade prior. The van had not started or run in at least a decade. I'm thinking the entire fuel system needed attention as my area mandated alcohol blended fuel. She was in a rural area, in a barn and the van was coated in a film that we had to pressure wash off. We put a new battery in it, verified all fluids then I smelled inside the fuel tank and I was amazed it smelled ok, turned the key and you could hear the fuel pump initialized and I cycled that 3 times and then the van started right up like it was run last week.

Her area did NOT mandate alcohol fuel when it was parked. The van required no further fuel system attention.