What should my cylinders look like?

[sail-ready]

Hello again,

Yesterday I pulled my plugs and when looking into the cylinders, I expected to see black. Instead, I saw brown like rust like or corrosion buildup. This can't be normal, can it?

This started because I was on a 4 day cruise and was forced to run several hours on water saturated gas. I think some water wound up in the tank in rough weather due to a bad fuel cap, though I have yet to prove that this is the culprit. Regardless, because my gasoline/ethanol blend was so saturated with water (fresh, not salt) I had to keep the mixture very rich to get adequate power. As I said, this was several hours worth of running.

A. I should see black carbon not brown corrosion in the cylinders, correct?
B. Is the water in the gas a reasonable cause of this corrosion, or should I be looking for something else(I just drained the entire fuel tank).
C. Should I take any other maintenance steps given this corrosion, or just add new fuel and run (I'm replacing plugs, and new gas cap)

Many thanks as always.

[hanleyclifford]

The atomic 4 can certainly survive such an episode. You should have a fuel filter/water separator installed near the fuel tank. In your case it wouldn't hurt to run a little MMO in the fuel for a spell.

[Al Schober]

You say you drained the fuel tank - USCG regs don't allow gas tanks to have drains. How did you get the fuel out? If you used the delivery fitting and just pumped on it until you got air, there still at least a couple of quarts of water in your fuel tank. The fuel pickup tube that goes to the engine doesn't go to the very bottom of the tank. With my tank, I can go from the fill fitting to the bottom of the tank with a slightly flexible tube (I use 1/4" Pex), and pump the tank dry. Getting the tank clean is a good start and cleaning up your fuel system. And put an O-ring on you fill cap - keep the deck water out.

[sail-ready]

'Drained' was probably poor wording. I pulled the tank access where the gauge float is inserted into the top of the tank then pumped it as dry as possible with a hand pump. I can do this with a few screws and is easier than pulling the fill tube.

So from the responses, the corrosion in the cylinders is not cause for concern and most likely caused by the watery fuel and not a larger issue?

Thanks everybody.

[sail-ready]

Oh, and I also purchased a new fuel filter/water separator. Any suggestions for getting these off as mine is quite stuck. At least now that I have the spare I can turn it without fear of crushing the old.

[hanleyclifford]

I keep an oil filter wrench on board for this purpose.

[quiesence65]

Not really wise to use a gasoline/ethanol mix....will rot your rubber gas lines over time and cause more trouble! Usually marinas sell the good stuff only....worth checking!

[sail-ready]

Not really wise to use a gasoline/ethanol mix....will rot your rubber gas lines over time and cause more trouble! Usually marinas sell the good stuff only....worth checking!

I didn't know this. So is that to say that the gas lines in my 10 yr old truck are made of a different material than the gas lines to my 45 yr old atomic 4? MN has a 10% ethanol blend and I often bring my own fuel to the boat (about half the cost even with road tax).

[quiesence65]

Gas lines in motor vehicles are "generally" from some type of metal, are they not? Boats tend to use rubber??? lines ...and there's the rub! If you have rubber lines on your A4,.....like most others I believe......you should use only marine gas with no ethanol! How do I know??.....I have seen the crud in the carburators /fuel filters of boats that have saved a few $$$ using ethanol gas....the crud is the rotted insides of the aforementioned gas lines. Not worth the money saved!

[sail-ready]

Gas lines in motor vehicles are "generally" from some type of metal, are they not? Boats tend to use rubber??? lines ...and there's the rub! If you have rubber lines on your A4,.....like most others I believe......you should use only marine gas with no ethanol! How do I know??.....I have seen the crud in the carburators /fuel filters of boats that have saved a few $$$ using ethanol gas....the crud is the rotted insides of the aforementioned gas lines. Not worth the money saved!

Ahh, understand. I've seen the light, thanks.

[Loki9]

What is this "marine gas" you speak of?? Certainly not available in New York state, or anywhere in the northeast that I know. E10 only in these parts.

Modern rubber fuel hose is able to handle E10 without issues.

[romantic comedy]

What is called marine gas, is 100 percent gas with no ethanol. Around here in S Florida, it is $1 more per gallon. Not many places have it. I have also seen it labeled RV gas.

The houses that we should use in our boats would be rated marine. I think the rating is A1? They are rated for alcohol and gasoline, so they would not deteriorate from the alcohol.

[Vermonstah]

Check out "Pure Gas"

Even in VT, you can find service stations and marinas that dispense ethanol free gas. I seem to recall that the allowance for ethanol free gas is related to this issue - the damage the ethanol causes to marine engines. I now use ethanol free in all my lawn tools / small engines, though some stations will not / cannot dispense more than 5 gallons into jerry cans, though certainly more if directly into a boat.

Also, I have an app on my iPhone called "Pure Gas" which will locate the nearest vendors of ethanol free gas and then provide (driving) directions to those locations. When I first used the app, it alerted me to at least a half dozen locations within a 15 mile radius of my home. Hope the app serves to be equally useful for others here.

I like being able to remove the ethanol variable from the equation when I am troubleshooting.

[hanleyclifford]

If you do any cruising you have to buy what is available. Best to use all ethanol rated hoses on your boat. Don't forget the deck fill hose (DAMHIKT). Also, keep extra filter/separator capacity on board.

[Loki9]

With very few exceptions, you won't find ethanol free gas on the water anywhere from Maine down to Maryland.

I guess pure-gas is nice if you can find it, but most of us just have to learn to live with E10.