I have been flying for about 5 months. I have OS glow engines and I use 10% fuel.
I notice that a brownish coat is forming on the cylinder heads and mufflers of my engines.
Is that normal? I tried alcohol with a toothbrush but it did not remove it.

That brownish coating is burnt castor oil. You can remove it by soaking the affected parts in a crock pot with hot antifreeze. You can avoid it in the first place by using a fuel that doesn't contain castor oil.

I am using the Omega pink 10% fuel I get at the hobbyshop.

Anything different you may suggest? Does the castor oil has its advantages too?

Thanks,

What you are getting is bake-on castor varnish. Basically, when you run the engine, the fuel (which contains castor) spurts out of the carb and on to the hot cylinger etc. Since castor has a high flash-point (in other words, it burns at a much higher temperature. This by the way is why it is used as a lubricant- it remains intact and continues to lubricate when the other components of the fuel burn. That is another story) it does not burn but forms long polymeric chains that bake on to the surface in the form of a varnish. While this is normal, it may mean you are running the engine very rich.

Tuning the engine being another issue, it is normal for the brown staining to appear. Just ensure they stay brown and do not go black. When that happens, the varnish has oxidised & carbonised and will intefere with heat transfer from the engine surface i.e. your engine may overheat (though I have seen many engines operate well even in this condition). The best way to prevent this is to regularly (may be once a month) scrub down your engine with a tooth brush and soap water (you can also use the windex / Colin etc that you use to clean the airplane). Make sure you completely dry the engine afterwards with a hair drier or heat gun otherwise the MS parts will begin to rust. Scrubbing regularly only prevents the buildup of the varnish, you may have difficulty in removing it later though a wire brush and a bit of elbow-grease may help

If you already have difficulty removing the stains, just keep an eye on them. If they start to go black, you need to wash your engine. There are various ways to do that but the way I do it is to remove the needle, carb, backplate and glow plug and immerse the engine for a couple of days in plain alcohol. Some also use the crock-pot method (they boil the engine in anti-freeze). You may need to do a bit of scrubbing afterwards. Just ensure that you dont open up the head as then you may need another gasket

As always, prevention is better than cure

Ameyam

You need to know what fuel you are using- the composition. In my observation, 46-55 2c sized engines that are mounted vertically in trainers run fine with plain castor based fuel. Engines that are mounted inverted or in cowls or larger engines or 4c engines dont do too well on plain castor (just my observation, others may have different experiences) and need a synthetic based fuel.

Almost everyone will agree on this -Dont use fuel that contains no castor. Like I said, castor has a higher flash point than synthetic additives. So when the synthetic additives and methanol in fuel burn up (by chance if you run your engine too lean or it runs at a high temperature), castor is still busy forming the oily long-chain polymeric compounds and does not burn. Hence it provides greater protection to the engine. On the other hand, synthetic fuels burn much cleaner and will not give you that staining (typically called gunking). Best to use a fuel (or fuel containing lubricating oil) which contains some castor. I use Klotz 100 which contains 20-80 mix of castor & synthetic in the lube for added protection.

By the way, you havent mentioned which engine you are referring to

Ameyam

I only use morgan fuels cool power full synthetic GREEN. Never had a problem ever! Still as silver and shiny as they were out of the box.

Thanks so much for all your input.

I have 3 planes. 2 have the OS46 AX. The trainer has the cheap rattling sound 46LA.
The LA is the one that has the most amount of brown. I may have to adjust the fuel/air mixture.
I will ask someone at the fiel to help me.

Thanks,

A bigger question is Why Worry About It?? It dosn't hurt anything. I have used a crock pot to clean old engines before a rebuild but if you don't have a number of engines it isn't worth the time or money. One club I used to belong to had the pot and AF for members to use if they wanted. Usually got used just before an auction to clean up old engines that were going to be sold. Bet that made the light bulb come on over a few heads, thinking about that almost NIB they bought and why it didn't run so well when they got it home.[8D]

I use " Dawn Power Desolver " and get it at walmart in the soap department, it's designed for BBQ cleaning. Just spray it on " it comes out as a jell " let it set a couple minutes and scrub with an old toothbrush ( you can use a new one if you want to ) then hose it off REALLY good brushing it a little as you hose it off . Works great !!! Just don't leave it on to long and be sure to rinse it well as if you don't it will give an etch look to your muffler etc..
ENJOY !!! RED

Harry don,t fix it, there ain,t nothing wrong and no you do not have to start removing the engines every few months and taking them apart for cleaning, that would be silly.

Yes the varnish is a residue from the castor and the higher the castor content of the fuel the more you will see this darkening on the external portion of engine. You said you use Omega fuel, If I am not mistaken Omega uses an oil package that consist of around one third of the oil content is castor and the balance is synthetic. Someone please correct me if I am wrong, I do not use morgan fuels.

Now some of the Morgan fuel have no castor and many blenders have fuels using oil packages that consist of only around two or three percent of the oil is castor and that is what a lot of us use.

Yes some castor is desirable as it provides a greater safety margin of a few degrees before it breaks down. This for those time when we mess up and have a lean run for various reasons.

The reason your LA 40 throws more oil is plain bering engines love to throw oil out around the crankshaft expecially as they wear. This is normal and not a problem.

The bottom line is Don,t fix it, if its not broke. If it throttles and runs well then its not broke.

John

Why would you want to go through the trouble/PITA it is to clean a glow fuel engine if you dont have to?????

Just switch to Cool Power - Same fuel but different oil. It's all I use

I'll go along with the 'why worry about it' and use Dawn Power dissolver comments. I will take off a muffler now and then and clean it just for aesthetic purposes but normally I leave the engine alone until the time comes to take it out for some reason then I clean it with Dawn, a scotchbrite pad, oil it up and ready to go again. And I like some cstor in my fuel but I don't want to start that battle again!

I don't mean to fix something that is not broken.
My concern was because the manual of the engine states that deposits on the engine will cause it to heat more. And engine should be kept clean.

You said that you have been flying for five months and thats great but its hardly enough time to have an exccessively coated engine and to need to remove an give it crock pot baths or as one poster said to remove and take off carbs, and back plates so forth.

Yes those techniques do work for a thoughly coated engine but its not time for that yet.

If a little discoloration around the cylinder head and around the header/muffler bothers you, just reduce the castor content of your fuel as one poster noted simply by changing to one with less castor or simply no castor.

The fuel you use is about one third of the oil is castor. You will find far more folks use fuel where about only three percent of the oil is castor. Thats for some of us who prefer to retain some of the benefits of castor. Or you can just use fuel with no castor.

In the distant past all glow fuels consisted of 100 percent castor and yes the varnish built up far faster and yes if you wanted a pristine engine it was neccessary to remove and cleanup far more often. Most folks back when just did not worry about it much as running problems from this were much, much further down down the line.

John

While it is almost unavoidable to get Castor stains on engines, you DO need to be aware that stains can point to a problem that newbies tend to overlook...

Namely that cap screws tend to loosen when the engine has been run for a while.

That lets the castor seep from the engine/cylinder head and other areas.

If you see castor stains on your engine you are advised to run the engine until warm, then remove one cap screw at a time, put thread lock on the screw ( after cleaning ) and partially re-tighten them down. Then torque them back down evenly alternating screws to get a good seal.



The engine should NOT continue to produce castor stains unless you spill fuel on the engine itself.


So DO pay attention to castor stains, they may represent a problem you may have overlooked.

OPJOSE,

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You raise an important fact. I have 3 OS engines and I use the same fuel and flew all 3 the same amount of time.</p>

However only one (the LA) has a lot of stains and that stain is mostly on the top of the cylinder.</p>

And that engine beeing an LA has a metallic rattling sound since the first time I started it.</p>

The hobby shop told me it was OK, and that all LA engines have this noise.</p>

I am not a handy person and I know very little about engines, I would not try to uncrew the head myself.</p>

I will ask a friend for help.</p>

Thanks,</p>

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Excellent point

and indeed its always wise for every one to check head tightness form time to time but especially when the engine is new even when one is using fuel with no caster and without which the varnish cannot serve as a pointer to a loose head.

Just one more additional thought. When an engine has been carelessly stored and it has used fuel with 'some caster' this same varnish which yes of course will gum up the moving parts but at the same time this varnish can serve as a preservative and even minimising the occurance of rust. Freeing up a gummed engine is not a hugh issue and can usually be done with the application of heat in various forms.

John

The LA series engine have a plain main bering and this type engine will require slightly greater crankshaft end play than a ball bering engine (All engines will have some endplay although to various degrees).

All plain bering engine will demonstrate some of this rattling which most often shows up while the engine is idled down and will sound somewhat like a boiling teakettle. As the engine wears throughout its practical wear life this rattle effect at idle will get more pronounced but is not a problem in itself.

Your LHS folks were correct. I use to love the old K&B Sportster's especially the little .20 and .28's that I called the teakettles. Shoot they didn't really get good untill they rattled big time at idle.

John

Someone at the field mentioned although the LA series are cheap and weak, they last forever.
Is that correct?

You do not have to remove the cylinder head, nor would I advise you to do so.

You should however tighten the screws down with the engine warm, or for added safety do as I mentioned and take the opportunity to add lock-tite on one screw at a time.

As far as the metalic noise... If you've lost the small thin thrust washer ( something newbies tend to do! ) the crank shaft will move back and forth causing the noise.

This is not good.... check to see if the thrust washer is there under the prop hub. If not get a replacement asap.

So, all I have to do is warm up the engine and tighten the screws?
Is there a specific force for the tightening? This is what I am concerned about.

Let the engine warm up and tighten the cap screws with an allen wrench.

You'll find that you'll be able to turn the screws another 1/4 turn or so without a lot of resistance, beyond that it requires quite a bit of force.

You'll want more force than you can apply with the short arm of the allen wrench, but less than the maximum you could apply with the long arm.

I don't know what the actual torque figures are.

It is typical for cap screws to come loose, particularly on engines that have never had this done.

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I ran the engine for 3 minutes and tried to thighten the head screws. They hardly moved.</p>

However, the glow plug was not thight at all. Someone had told me not to do it too tight.</p>

I was able to turn the it 1/4 of a turn with not much effort.</p>

Was the glow plug supposed to be thight?</p>

Thanks,</p></font>

You really need an instructor. A glow plug should not be over tight but yes, it has to be tight. I have seen people over tighten to the point the threads were warped or angled up, that is almost a strip job, over tight. LA engines are great. It's a plain bushing they use for a bearing and the engines last a very long time, not forever. When one is starting to wear out you will be seeing a lot of gray color in the exhaust, not to be confused with a loose muffler, it will start spitting out gray slowly and as time goes on more and more. I have a couple of old .40 LAs that are worn out from use in over weight trainers over a number of years, they still run and get used once in a while. I used a lot of the .46 LAs in my fun fly planes and have never worn one out. The loose glow plug is the point of the fuel blow out. I used a lot of the .46 and the first thing I did after pulling the engines out of the box was to remove the head screws one at a time and use lock tite on them. Every one of the engines I had would loosen up the head screws right away unless I did this.