Awhile back I saw a member talking about how it took two gallons of fuel
to get his Saito broken-in to where he could get it to idle. This is a case
where the Guy started the engine about 4 turns out on the main, the low
speed factory set way too rich....left the glow starter on and just let the
engine run like that, slobbering rich beyond belief, probably tank after tank,
thinking he was doing his motor good. If he would have removed the glow
starter the engine would have drowned-out and quit.

What really happened was, he glazed the cylinder, and the compression
was so low, the thing wouldn't hold an idle. His cure then was to run the
engine for hours and hours....gradually leaning the engine out a click or
so at a time, until the engine reached a point where the temperature got
high enough, the RPM's got high enough, and the cylinder pressure got
high enough, and the ring was able to gradually scrape away the glaze,
and get to some respectable semblance of compression where the
engine would idle.

Would you by a new Honda generator and have the mechanic adjust
the carb so the engine ran sloppy rich, only about half the proper RPM
....so you could get a "good break-in" ? How about a chain saw ?

Would you buy a new motorcycle and have the mechanic do the same thing ?
How about an automobile ? Why then your aero-model engine ? Like William R.
stated, all engines are basically the same, made from the same materials.
This sloppy rich "ringed engine break-in thing" is absolutely preposterous. It
has no basis in practicality , practice, or fact. It is a stupid, incorrect Internet
Tale.

The correct way to operate a ringed engine on break-in is to allow the
engine warm up for a moment, at 1/4 throttle, then run it up to full RPM, and
adjust the engine about 500 rpm's down from full lean, and let it run for a
few minutes. Occasionally peak the engine to full RPM for about 20 seconds,
then go back to the slightly rich position. After 5 minutes, shut the engine
off and let it cool for about 20 minutes. Do the same three more times, a total
of twenty minutes, with about 5 of those minutes running at full peak.

The engine is sufficiently broken-in, will idle correctly, and will run perfectly.

FBD.

I dont think you can compare car engine break ins to these engines ..the way we run in glow engines is horrendous to me, I still have a hard time running a brand new engine at WOT the mating of parts is done in a totally different way with glow engines they do not have the oil passages that car engines do... run in a car engine at wot and you then have a very good boat anchor!!!

there are different objectives between various engines
example: when talking about the ring.. in glow engines the object is to seat it against the wall..while in a car engine it is important to develope the taper in the ring against the wall

there is far more to it than just this to which I am not prepared to go into here as it gets off topic..but different engines have different needs you cant lump all engines in one basket

Glazed cylinders are caused by heat and small worn bits of metal plugging the valleys between high points. For the life of me, I don't know how an engine can get glazed with lots of raw fuel and oil pouring over the cylinder walls. Running excessively rich should only be done for a tank or so and helps to prevent the engine from overheating, washes out any worn metal, and helps to seal the rings which means more compression which in push's the rings out against the metal.

The main differance is that car engines are much larger and are initally run in at the factory. The larger size means that the small gaps and any out of roundness will mean a much smaller compared to the total size and volumn, thus less loss of seal as a percentage of air leaked past compared to total volumn. Also they are water cooled with a thermostat so any additional heat from friction is automatically compensated for.

well I just happen to have here in my hand a brand new 52 ringed 4 stroke lets see what the break in is in the book
ok here we go
1.start the engine per start up procedure
2.Once the engine has started, at full throttle setting, adjust the high speed needle valve to a very(or ''sloppy'') rich position. Let the engine run for two or three minutes.
Stop the engine
3 It says to repeat the procedure with a slightly leaner setting
after about 30 mins of actual run time the engine should be ready to fly
4 Fly the plane with the engine as rich as possibly while still having adequate power
leaning it a little more on each of the next ten flight by then the engine should be able to hold a normal setting

with a big warning at the bottom \
never run this engine lean and always let the engine cool this will prevent any premature wear or damage to the ring

I know everyone means well but I have always followed the book and never had any complaints about any brand engine I have ran
and it's been a few

this is actually what glazing is
The primary deterrent of break in is this heat. Allowing to much heat to build up at the ring to cylinder wall interface will cause the lubricating oil that is present to break down and glaze the cylinder wall surface. This glaze will prevent any further seating of the piston rings. If glazing is allowed to happen break in will never occur. We must achieve a happy medium where we are pushing on the ring hard enough to wear it in but not hard enough to generate enough heat to cause glazing. If glazing should occur, the only remedy is to remove the effected cylinder, re-hone it and replace the piston rings and start the whole process over again.


the oil cooks onto the metal like a glazed coffee cup
so I think running sloppy rich ensures cool running it should break in fine
I think 2 gallons is excess but my experience has been that my engines run better after two to three gallons of run time but not all in break in mode just a tad to the rich side

You have it partially right, but it is a light film of oxidized oil. The oil then picks up bits of microscopic metal. However that type of glaze can actually be cleaned out or at least prevented with high detergent oil. The glaze that cannot be removed is caused by high surface temps and bits of microscopic metal actually fuse to the surface.

Not high detergent oil is a no no in aircraft engines.

http://www.prime-mover.com/Engines/L...Operation.html

Well I'm just going to do it like the manual says it's worked on every engine so far 2 or 4 stroke.

One of my childhood mentors always said "break it in on the airplane" because it will get better cooling airflow and the engine will be operating in it's intended environment.
I agree with that...usually...unless it's an engine that I feel might benefit from a little bench "testing"...besides, sometimes I just want to hear it's "voice" and maybe bug the neighbors a little...

----------------


I'm not argueing with you, so don't take my comments that way, please.

I used to fly control line exclusively when I was young. All I could afford.

Ever have a new engine get off (launched) just right, then something changes and the engine goes unmercifully lean? It's happened to me and it is why I won't break-in an engine on a model airplane. To have to listen to your engine melt itself down for an entire tank full of fuel can be agonizing.

Yeah, R/C is different. We can throttle back and land. It's just something with me, I guess. I like knowing exactly what is happening to my engine during its initial runs. Once proclaimed as "broken-in", my attitude changes in a most curious fashion. It just doesn't matter as much any more.

I hear ya Artisan...I flew a lot of controlline in the 70's...

Sometimes it's just fun to run an engine on the stand. A friend has a Pegasus, (O.S. opposed 4 cyl.) and that was fun to get set up and test run

I ran an O.S. 1.08 not long ago, and during the first (6 oz. ) tank running excessively rich, I measured a cyl. head temp of about 110 degrees. I figured that was too cold...so I leaned it to get the cyl. head temp up to about 160 or so, and to be able to remove the plug battery. I'm wondering now though, if it really is possable to "glaze" a cyl. at such a low temp? (personally, I don't think so )
Maybe if there was a tremendous ammount of fuel passed through it?

One thing not yet mentioned is...do you really need to heat treat, heat cycle the ring to "temper" it as one of our local "experts" says?

You folks have the terminology wrong. Glazing is a build up on the cylinder wall
from running too rich in a blow-by situation. Cylinder scuffing (damage) is the
result of running too lean and overheating the ring. Scuffing is not easy to do
with the amount of oil we have in the fuel.

What Planet was that on ?

Glazing is not caused by heat. It is cause mainly by the failure of the
ring to seat. If the ring was seated, and the engine was running at a proper
temperature....there would be no glazing. Glazing occurs where the ring is not
seating....and where the ring is not seating there is blow-by. The accumulation
of fuel and oil getting past the ring builds up on the cylinder wall.

Running an engine lean, overheating it to the point that the oil breaks down,
allowing the ring to scuff on, and damage the cylinder wall will result in a loss
of seal to the cylinder wall, and a loss of compression. This will result in blow-by
which will in turn manifest itself....ultimately.... as glazing on the cylinder wall.

Normally an engine that experiences this catastrophe dies anyway from lack of
compression., and probably will not run. If it does run, it will bring you back to
point you started at....that being an engine that won't idle properly....due to
low compression and cylinder glazing, and an engine that is lacking satisfactory
performance for obvious reasons.

FBD.

Let's see. Most of the world by definition is average so JettPilot just called a great proportion of you guys reading this about as smart as a rock.

I'll post it from another engine website
Glazing is caused by HEAT, this heat breakdowns oil and cause it to GLAZE to the cylinder wall

The primary deterrent of break in is this heat. Allowing to much heat to build up at the ring to cylinder wall interface will cause the lubricating oil that is present to break down and glaze the cylinder wall surface. This glaze will prevent any further seating of the piston rings. If glazing is allowed to happen break in will never occur. Also, if too little pressure (throttle) is used during the break-in period glazing will also occur.
It read the same on every engine website
HEAT causes oil to break down and GLAZE
GLAZE Glaze is a thin shiny coating, or the act of applying the coating.
Not sure where you are getting this blow by thing from blow will result from glazing when the ring won't seal not cause glazing

Gee thanks for letting me know I am not much smarter then a rock since I break my engines by the directions instead of thinking that I know more then the guys that built the engine

OK folks, a little clarification, pointing to earlier posts, and general carping.

Please note the following is ONLY for ringed engines.

I’ll start with glazing. There is “Real� glazing, and it is indeed as skiman762 says, caused by oil breakdown from excess heat. But this heat can easily be local, confined to the point of contact between the ring and cylinder wall. The rest of the engine can still be relatively cold.

There are other conditions that are usually called glazing but are not. As an example, an engine with high time can have the walls polished to the point that a new ring wont seat. When new are installed the cylinder wall has to be scuffed to make the new ring seat. We generally call this “Breaking the glaze� even though it’s not a true glaze.

Then we have a near new engine that has been run in with a low throttle setting and an excess of oil. The result here is that the ring polishes the cylinder wall without itself wearing to match. Then when the engine goes into service, running at higher throttle settings, the cylinder pressure comes up forcing the ring more firmly into the cylinder wall. Finally, the ring starts to seat. And since the wall is already polished, this seating can take several hours running time.

So, repeating myself, with the engine on a stand for initial running, peak the high speed needle immediately, then drop the throttle to a high idle or mid range speed for 15-20 seconds. Next go back to high rpm for 5 seconds or so, then back down. Do this repeatedly for about five minutes, then strap it in a plane and go fly. Keep it 400-500 rpm rich on the top end for a while, after an hour or so you can go higher and start leaning the low speed.

What this does on initial running is force the ring into the wall, then before heat has a chance to build drop the speed and let everything oil up again. You get the ring to seat quickly and safely.

Some engines I’ve put together have had less than 30 seconds break in before going to the drag strip. At the same time, those engines seldom ran more than five minutes total time between overhauls.

Now the carping. At least 1/3 of the posts in this thread add nothing at all, others are merely repeating themselves.

Bill.

skidman 672,

Hi, from one idiot rock to another

STFU???? Nice!

Bill....I'm talking about the glazing that can occur from a an engine that was
improperly run-in, and that certaimly does occur. Not a rare "point of contact
glaze" caused by oil break down....

The glazing, as I stated earlier is caused by oil getting by the rings (blow-by)
and accumulating on the cylinder wall. Yes, of course the heat of combustion
bakes the oil to the cylinder wall.

How do the guys think it got stuck there ? Bubble gum ? This is the normal
heat of combustion, not an overheated senerio...in fact, we are talking about an
engine that is running sloopy rich...too cool as a mater of fact.

In the case I am refering to, the topic at hand....heat does not "cause" glazing.
The oil that is getting past the rings, due to the improper operation of the engine
and the failure of the rings to seat, getting baked onto the cylinder wall by normal
combustion temperatures....

....results in a glazed cylinder wall, and a poor performing engine. I don't know how
to state it any simpler than that.

Maybe someone can come up with some other type of glaze to throw into the mix.
How about a glazed donut ? Too much oil, or too much heat ?

FBD.

Your right 100% I'm wrong because I'm no smarter then a rock and will go have a nice hot cup of STFU...everyone happy now ?
good

Skiman,

I'm with you. Want to share a bottle of STFU with me?? Just a couple of rocks sharing our idiocy together?

Flyboy

once again your expertise comes thru the flack. That you for the explanation and clarification
without being distracted by the internet experts.

Big Bopper.

Glaze?? Isn't that the stuff they put on unfinished pottery before they fire it???

yeah I guess the experts at Lycoming are wrong too
I'm not bold enough to claim to be something I'm not so I simply posted something
from Lycoming but hey they have only made some 300,000 aircraft engines what would they know about
breaking in an engine and what causes glazing
Here's your sign

I suspect this is aimed at me because I've mentioned it a couple of times before in similar threads. I also mentioned in the other threads that I adapted some information I found on the running in of diesel engines to a ringed engine because similar materials are used, steel liners and cast iron pistons/rings. It made sense to me so I figured it was worthwhile passing on. If nothing else, I learned a few things about cast iron. All I'll suggest is to have a read through http://www3.bc.sympatico.ca/dieselco...ut_diesels.htm and make up your own minds.