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My Fuel blamed for Rust

Old 01-31-2005, 12:17 PM
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3d-aholic
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Default My Fuel blamed for Rust

I have a Magnum 2 stroke engine that the bearings and crank rusted up. Several people think my homebrewing fuel is to blame. I've been mixing up a 2 stroke blend of 18% oil, 15% Nitro. Using Klotz and Bakers Grade AA castor at 75:25 % .

Does store bought fuel have anything else in there to preserve the motor? Do they put after-run type conditioners in there or something?
Old 01-31-2005, 01:09 PM
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Default RE: My Fuel blamed for Rust

Many of the fuel manufacturers claim to add rust inhibitors. Do these help - I do not know. I suspect your problems may be more due to not using after-run oil and not getting all the unburnt fuel out at the end of the day. Just pulling the fuel line will not do it. You must put the glow plug ignitor on and turn the engine over until it no longer fires.

In the "good old days", many of us used to run our engines on castor based fuels - never used after run oil, never fully got all the unburnt fuel out - and had no rust problems. Just go figure?!


Paul
Old 01-31-2005, 01:38 PM
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Default RE: My Fuel blamed for Rust

I figured the rust inhibitor that they claim to add is called OIL... lol

Yes...I worry too that sometimes I forget to disconnect the fuel from the tank. The residual fuel left in the tanks tends to keep the methanol and water vapors directly connected to a sort of Humidifier.

Any idea what these rust inhibitors are. I have switched to the green stuff to see if this helps things.
Old 02-01-2005, 10:57 AM
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Jim Thomerson
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Default RE: My Fuel blamed for Rust

Given as much castor as you are running, I'm surprised you have a rust problem.

Jim
Old 02-01-2005, 01:01 PM
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Default RE: My Fuel blamed for Rust

Well thats what I thought but I seem to be doing better with less castor. Its like the castor turns into a gooey mess in there that looks to be an attractent for water and dirt.... I'm thinking about switching away from the castor altogether. I switched away on my 4 strokes and things were better but I was still using castor in my 2 strokes up to now.

Should I put in an ounce per gallon of Marvel Mystery Oil in there as a rust inhibitor.
Old 02-01-2005, 03:23 PM
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Jim Thomerson
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Default RE: My Fuel blamed for Rust

Are you sure you have rust and not just castor crud? The two don't generally go together. I don't know if Marvel mystery oil will mix with glow fuel.

Jim
Old 02-01-2005, 03:35 PM
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Default RE: My Fuel blamed for Rust

Hmm....Yes, I have both...but this requires sanding to remove and and on some parts pits remain...

1 ounce to 128 ounces might mix though... The must be putting something obvious in there.
Old 02-01-2005, 07:42 PM
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Default RE: My Fuel blamed for Rust

Marvel mystery oil does not mix with methanol.

Paul
Old 02-01-2005, 08:01 PM
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Default RE: My Fuel blamed for Rust

Ok, what is the secret rust inhibitor thats miscible in methanol.
Old 02-01-2005, 09:18 PM
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Default RE: My Fuel blamed for Rust

ORIGINAL: 3d-aholic

Ok, what is the secret rust inhibitor thats miscible in methanol.
Castor

In your engine thread you said it'd sat for 8 months. This isn't normally long enough for castor to start gumming up but who knows? Gummy castor can make the bearings feel very rough but it's easily cleaned out if you remove the bearings. A bit of heat to soften it, dip in some fuel to dissolve it...repeat until free
Old 02-01-2005, 09:30 PM
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Default RE: My Fuel blamed for Rust

No castor with heat will polymerize....that supposedly is why its better as a protectant at high temps. The polymerized gummy texture is the same thing it does when it hydrolizes with age. Put some castor in a pan and turn on the gas temps to 400 degrees and you see what I mean...it will smoke and then turn yelloish and then brownish...and be stuck down at the bottom of your pot. Take some synth and do the same thing and it will smoke to high heaven but not turn into something else....supposedly
Old 02-09-2005, 01:27 PM
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Default RE: My Fuel blamed for Rust

3D-Aholic
That is one of the bad things in mixing your own fuel. the Major Fuel Manf. spend quite a
sum of money on the additivies in their fuel to prevent this problem.
Powermaster
Old 02-09-2005, 02:32 PM
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Default RE: My Fuel blamed for Rust

I don't see how the major manufacturers can add anything of significance in the fuel to stop rust. If its at a concentration greater than a few percent -- it would effect engine performance. And a concentration of only a few percent, how could it have much of an effect after the methanol and Nitro evaporatate?

One thing I did was switch from Klotz to Morgan's homebrew oil which supposedly has these other additives already in the oil.
Old 02-12-2005, 04:02 PM
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Default RE: My Fuel blamed for Rust

Having some experience with water treatment for large 1000 HP water tube boilers and studying some MSDS sheets, the fuel manufactures probably add something to bring the Ph up as nitro and even methanol is slightly acidic, also some tool oils have oxygen scavengers which help, maybe they add similar additives to their fuel.
Old 02-28-2005, 05:00 AM
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Default RE: My Fuel blamed for Rust

Any oil that mixes with methanol will also mix with water to some degree. Over time steel parts will corrode. the only way to keep corrosion to a minimum is to flush out your engine with non hydroscopic oil, petroleum products work great. The model boat people have a good handle on this concept, they pull the glowplug and circulate lots of oil through their engines at the end of every outing. Motorcycle racers have reported corrosion on their crankshafts after longterm use of ester and castor oils.
Old 03-01-2005, 12:23 AM
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Default RE: My Fuel blamed for Rust

I have only started reading about making your own fuel, so i really dont know what im talking about yet, but i have read that some sources of nitromethane are less than pure. Apparently one of the byproducts of the distillation that can end up in the Nitro is nitric acid, which (if this is in fact the case) will cause some severe rust and corrosion regardless of any after run oil, or castor content in the fuel. Are you confident in your source for the nitromethane?

Sketts
Old 03-03-2005, 11:24 PM
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Default RE: My Fuel blamed for Rust

I believe Nitric Acid is used in the manufacturer of Nitro....so all sources will have trace amount of Nitric Acid.

According to my chemical distributor. Nitromethane only really comes from 2 principal sources. Chinese Nitro and American Made Dow Nitro.

The stuff he provides is 99.8% pure. Thats reagent grade. Most of the significant impurities are other paraffins such as nitroethane (probably the most significant), nitropropane, etc. Given the nitro is only at 15%, these other impurities are really fairly insignificant. I read that some fuel manufacturers claim they are able to get nitro at 99.9% and therefore they say that 1 tenth of a percent is significant and makes their fuel better.

As a chemist, I don't I buy it....literally.
Old 03-04-2005, 11:03 PM
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Default RE: My Fuel blamed for Rust

I guess that goes to show, trust 10% of what you hear, and 1/2 of what you see

sketts
Old 03-06-2005, 10:50 AM
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Default RE: My Fuel blamed for Rust

Nitric Acid is a byproduct of the combustion of nitro. The richer the mixture the more nitric acid. However nitric acid is very reactive and sitting in a pool will slowly degrade. Most of the nitric acid will burn off in the exhaust stream and will leave a powdery white corrosion in the exhaust stack of any high nitro engine after just a single run. However I doubt any nitric acid remains in any model engine in any amount to cause significant harm. You will find the crankcases of high nitro racing engines as clean as any sport engine.

However that said nitro itself is a very mild acid and should be burned off after each run.

Water itself doesn't cause rust, water is the electrolyte to allow the oxygen dissolved in the water and fuel to react with metals. If the water is diluted with a significant amount of oil it loses its conductance and protects the metal. That is why fuel with 100% castor oil will rarely have rust. That is why castor oil is the best after run oil.
Old 03-07-2005, 01:03 AM
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Default RE: My Fuel blamed for Rust

That is why castor oil is the best after run oil.
___
Chemically, there is very little difference between castor oil and Klotz for example. The synthetics we run nowadays are "synth" castor--thats the chemical model they try and copy.

The model engine that rusted was running with a 30% Bakers Grade AA Castor blended fuel.
Old 04-04-2005, 09:43 AM
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Default RE: My Fuel blamed for Rust

3D It sounds like you have more than one engine. If so are the other engines effected? Did you get this engine used? Klotz is a major player for syn oil and is used in 6 major brand fuels I know of. Being your home brewing and want to cut down on caster, KL100 is 20% caster and premo caster at that. Are you leaving fuel exposed to air or not sealed for long times?
Old 04-04-2005, 10:26 AM
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Default RE: My Fuel blamed for Rust

[link=http://www.modeltechnics.com]ModelTechnics[/link]

Click on the "Ingredients" label, then on "Mixing your own fuel" at the bottom of the page. Point 6 might be useful to you. I would very much like to start mizing my own fuel for my model car but do not know a supplier of ingredients in England.
Old 04-04-2005, 10:34 AM
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Default RE: My Fuel blamed for Rust

I probably left fuel in the engine. I don't have any other problems with engines yet.

However, I would add that I started using Morgan's oil and found it to be better than Klotz...and its cheaper, $20/gallon , no -minimum!


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