JohnC
New Member
Posts: 4
Loc: Yorkshire, England
Reg: 12-24-01
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 01-10-02 08:02 AM - Post#3854
I have an OS61-LXH which has been making a peculiar engine note when the throttle is over about 60%. I took the head off, and noticed a build up of black carbon over the top of the piston.A flake of this carbon was 'missing' and I assume it has gone down the side of the piston. The bore and the side of the piston are visibly scored for a width of about 10mm. The question I have for the experienced fliers amongst you is how often do you take your engine apart and clean away the carbon deposits? What do you use to clean it off? btw. The engine has always been run on CoolPower 10%, and has always seemed to be running a bit hot. It has had maybe 8-10 gallons through it. Is this a normal symptom of an engine damaged in this way?. I am debating whether to repair the engine or buy a new one and keep it for spares. It doesn't seem too much difference in price between a new piston+liner and an entire engine!. Can someone please explain to me the steps involved in replacing the damaged parts. It is knowledge I think I should know!. Thanks in advance, John C.
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Rudy
Full Time Senior Member
Posts: 4841
Loc: Houston, TX USA
Reg: 03-14-00
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 01-10-02 01:22 PM - Post#3855
In response to JohnC
I open the engine when new to check for metal shavings but other wise I don't mess with it untill I hear a problem.Rudy Ackerman
Houston TX
If Wile E. Coyote had enough money to buy
all that ACME crap,
why didn't he just buy dinner? |
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Doug
Senior Member
Posts: 823
Loc: Naples Fl. USA
Reg: 11-17-00
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01-10-02 01:35 PM - Post#3856
In response to Rudy
Well, You need to make sure that what you are seeing is scoring. Can you "catch" your fingernail in it? Does it appear that "piston" material has smeared onto the liner? Does the engine still have "good" compression (when turning slowly is it difficult to turn a full turn and does it "spring" back)? . If the answer to the above is yes,yes,no, then you need to take some action. With the Cylinder Head, carb and back plate removed heat the entire engine in the oven. until you can touch but not hold on to it (about 225f). Using an old tooth brush gently pry up on the cylinder at the exhaust port then grasp the protruding cylinder with a rag and remove it. With the piston at bottom center remove the "big" end of the connecting rod from the crank pin. Assuming the "prop nut" and clutch is removed, tap the "back" (where the back cover was) on a piece of wood and the crank (and likely the rear bearing will fall out. Using a plastic rod tap the front bearing out. The engine is now fully dissembled except for the wrist pin. You may be able to "hone" the cylinder but if any of the transferred Aluminum from the piston remains the engine will again fail. If the piston has "black smeared" areas then it is a goner. Get a "new" piston,sleeve and ring and replace the main bearings reversing the above procedure. It is normal for carbon to build up on the top of the piston and it is unlikely the source of your "scoring".
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Christopher J
Full Time Senior Member
Posts: 3351
Loc: Kansas City, MO
Reg: 11-09-01
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01-10-02 01:36 PM - Post#3857
In response to Doug
If you have a scared section of sleeve and piston I would advise replacing the sleeve and ring. The piston should be fine as it the ring that contacts the sleeve and not the piston. As Rudy mentioned, I don't do anything to and engine as far as taking it apart unless I notice a problem with it. I will flush my carbs from time to time though. Carbon deposits like what you mention are I believe a sign of a hot running engine and you did mention that it seemed to always be running hot to you. After and if you rebuild it I recommend running Cool Power 15% instead of 10. This way you can run the engine richer and get the power you want. Christopher J
| Christopher J
East Coast Vario Field Rep
Size it up and then scale it down |
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Tom&JesseDay
Member
Posts: 66
Loc: Needham, MA, USA
Reg: 11-25-01
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01-10-02 03:55 PM - Post#3858
In response to Christopher J
How do you flush your carbs? This sounds pretty useful. Thanks, Tom
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nsacco
Senior Member
Posts: 453
Loc: Raleigh, NC, USA
Reg: 01-10-01
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 01-10-02 04:27 PM - Post#3859
In response to Tom&JesseDay
Unless you abuse the engine by wringing out every ounce of power from it, it should last a long time and not need much. There are many caveats to this however such as rust forming during storage, dirt entering the engine etc. There was a good discussion here a while ago regarding air filters on engines - I use them all the time. Dirt entering an engine during hovering (especially) and flying can cause scratches on the piston/cyl not necessarily the carbon. Bearings will eventually wear and should be replaced when they no longer feel smooth. They develop a kind of notchiness evident when turning the crank by hand. Obviously you must remove the engine to feel this. Lots of folks use some kind of after run oil after flying to mitigate the rust factor. Nothing wrong after flying, with loading up your engine with oil or some kind of after-run oil. Just be sure to remove the plug and turn the engine over before starting the next time or you can easily break pistons, connecting rods etc.
| Happy Flying!
It's not how much it costs, it's how much you can afford! |
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JohnC
New Member
Posts: 4
Loc: Yorkshire, England
Reg: 12-24-01
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 01-10-02 06:07 PM - Post#3860
In response to nsacco
Thanks very much for the advice everyone.The reason I think it was some carbon going down the side of the piston is the fact that there was a chunk missing and an oval shape about 7mm by 5mm of shiny piston visible. When I hold the engine to my ear and turn it by hand, I can actually hear air moving from one side of the piston to the other. When I get the 'pop' from the exhaust, it is the piston vacuum being released (from the downward stroke) - I assume this is not normal. I removed the liner and tried smoothing the grooves with some very fine emery cloth. It has not made it much better however. Anyhow, I have ordered a new engine, and I will repair this one in slow time or use it for spares for the new one. Thanks again everyone
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Christopher J
Full Time Senior Member
Posts: 3351
Loc: Kansas City, MO
Reg: 11-09-01
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01-10-02 06:45 PM - Post#3861
In response to JohnC
To flush the carb remove it from the engine and attach fuel line to the carb at the nipple. Pump some fuel through it and you're done. The only time I ever did this was when running castor based fuel and the carb would be clogged. Now with synthetic based fuels this doesn't need to be done very often. Another reason to flush one is if you think you have dirt or debris in the carb.Christopher J
| Christopher J
East Coast Vario Field Rep
Size it up and then scale it down |
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Maxx
Senior Member
Posts: 304
Loc: Shreveport, Louisana, U.S...
Reg: 02-16-01
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01-10-02 08:10 PM - Post#3862
In response to Christopher J
JohnC, I assume you must be using airplane fuel in your engine, Coolpower makes 15% and 30% heli fuel that doesn't have any Castor oil and it works much better than airplane fuels. I believe the deposits you saw in your old engine were due to castor oil getting hot in your engine and "coking" the piston and ring! Just use an all synthetic oil heli fuel from Powermaster or Coolpower (there are other fuels that may be OK too; these are the two I have used) and your new engine should last much longer than the last one! Chris[This message has been edited by Maxx (edited 01-10-2002).]
| " Experience is what you get when you don't get what you expected..." |
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JohnC
New Member
Posts: 4
Loc: Yorkshire, England
Reg: 12-24-01
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01-11-02 07:55 AM - Post#3863
In response to Maxx
Maxx,I have only ever used CP10% in the engine - does this mix include castor? Anyhow, I have also ordered a case of CoolPower 15% and I think I will stick to this from now on  .
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Maxx
Senior Member
Posts: 304
Loc: Shreveport, Louisana, U.S...
Reg: 02-16-01
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 01-11-02 04:22 PM - Post#3864
In response to JohnC
Morgan Products makes Coolpower fuels and they make many types, The 15% HELI and the 30% HELI are the only ones I would use in a helicopter engine! Even 15% airplane fuel won't work as well as 15% heli fuel. Skyline and Revolution Models carry the heli fuel that has not only the correct type of oil but the correct amount too! Chris
| " Experience is what you get when you don't get what you expected..." |
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Dyehard
Senior Member
Posts: 272
Loc: Richlands, Va.
Reg: 01-27-01
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01-11-02 06:04 PM - Post#3865
In response to Maxx
Chris, according to everyone on the forums that has checked on it, Coolpower 15% airplane and HELI fuel are identical. 30% Coolpower uses a completely differant type and amount of oil, but the CP 15% Heli is just airplane fuel with a differant sticker on it.
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Maxx
Senior Member
Posts: 304
Loc: Shreveport, Louisana, U.S...
Reg: 02-16-01
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01-11-02 07:20 PM - Post#3866
In response to Dyehard
Hi Dyehard, yea, I know the Coolpower is the same thimg but I've found other fuels that are not...I find it's easier to tell people "get the stuff with the Heli sticker" than to try to tell them which mfg's. are foolin' ya' and which ones aren't! <G>. Chris
| " Experience is what you get when you don't get what you expected..." |
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Doug
Senior Member
Posts: 823
Loc: Naples Fl. USA
Reg: 11-17-00
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01-11-02 07:32 PM - Post#3867
In response to Maxx
Back to the original question:I don't routinely take my engines apart. When I start it I Feel for smoothness and I know how "hard" it is to turn with the starter. I notice how it performs in a hard climb out. If I "use" a plug I will take the muffler off and take a look at the cylinder. I also take the back plate off from time to time to check on corrosion and the condition of the bearing retainer. Otherwise I just fuel it and fly it. Normally the carbon on the piston causes no harm and I doubt it caused your problem. [This message has been edited by Doug (edited 01-11-2002).]
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DK64
New Member
Posts: 3
Loc: Hanford, CA
Reg: 12-27-01
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01-12-02 07:17 AM - Post#3868
In response to Doug
Never....well, unless it is broken but i haven't had that happen yet.
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