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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › Redline leans out during flight
06-03-2009 01:34 PM  9 years agoPost 1
Olli-Pekka Mahrberg

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Finland, Joensuu

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Hi Guys,

I'm again having some problems with the Redline motor. I just installed an extra shim to the head to solve the pre-ignition problem. I've also changed the carb to the newer version. The engine runs very rich at idle and max throttle, runs cool and smooth in normal mode (hovering) and runs well in idle 1 when doing manouvers that don't bog the head. The problems is that if I bog the head for a long period of time, the engine suddenly leans out and gets really hot. The motor doesn't seem to have as much power as it should have according to some videos that I've seen. I know that middle range leaning should be fixed by richening low and high end needles. The odd thing is that the high end needle is already 3 turns open. Shouldn't it be around 2 turns open? To my knowledge the motor shouldn't get hot if the mixture is rich.

What do you think?

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06-03-2009 03:36 PM  9 years agoPost 2
glydrjocky

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Livermore, CA - USA

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With the .004 shim installed I found the same bogging especially being 3 turns out. Engine seemed happier around 2.75 turns. As I leaned below that, an airleak in my fueling T filter reared its ugly head and the "bogging" came back. Fixed the T and managed to get below 2.5 turns. Temps never seemed particulary hot. I've since pulled the shim and tested that setup. This has made the engine temps much more responsive to needle position. Highest I had seen was around 200 after hammerning it around the sky on 20% CP. It almost seems like 20% is right on the edge of needing that first .004 shim. Without the shim I'm now some where between 2.75 and 2.5 turns.

What plug/fuel/pipe are you running?

The only people who truly know where the edge lies, are those who have gone over.

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06-03-2009 04:08 PM  9 years agoPost 3
JuanRodriguez

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The Villages, Florida

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The problems is that if I bog the head for a long period of time, the engine suddenly leans out and gets really hot.
If you're asking more of the motor than it can deliver by "bogging it continuously for a long time", the motor is going to get very hot. What you see next is the motor's RPM dropping due to the beginning stages of the motor seizing up vs "leaning out" due to a fuel delivery problem....

In my opinion, two entirely different problems. In either case, it will lead to the same result.....a scored piston/ring/liner......

Try managing your collective a little better and/or check your settings to determine if they are beyond what is recommended causing the motor to "bog".....

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06-03-2009 06:43 PM  9 years agoPost 4
Olli-Pekka Mahrberg

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Finland, Joensuu

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By "bogging it continuously for a long time" I meant full pitch climbs, continous tictocs and other "head boggin" moves. The motor seems to run lean even though the needles are set rich. The carb should be fine and there shouldn't be any air leaks. I can handle the collective pretty well and the motor shouldn't get very hot doing that kind of manouvres. I didn't mean that I'm flying at full pitch all the time.

The motor just doesn't seem to have the torque and doesn't gain rpm fast enough after bogging. I'm using OS8 plugs, Optifuel 30% and MP5SB pipe. Should be a good combo.

Here's a video from last winter. Now the motor can't handle that kind of flying without warming. Back then the middle range was too lean and the motor burned some plugs, now the problem is overheating.

Watch at YouTube

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06-03-2009 07:03 PM  9 years agoPost 5
JuanRodriguez

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The Villages, Florida

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Then, I would be checking the condition of the piston/ring/liner.....

Sounds to me that you may have a damaged motor due to overheating....

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06-03-2009 07:40 PM  9 years agoPost 6
glydrjocky

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Livermore, CA - USA

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Successive lean runs
Juan,

I'm curious about something here. If you have a number of short lean runs as I had with my airleaking filter does the ring take the brunt of the damage. In other words can it lose tension on the cylinder wall from each successive lean run. I looked at the cylinder walls in mine when I had the head off and they seem perfect yet this engine doesnt seem to have the snap that it had when new. Granted my flying style is more smooth flowing acro with lots of high throttle climbing manuevers and less radical 3D. Much like Olli, I'd swear mine has lost a bit of power over time rather than gained it.

Question is, when do you bite the bullet, tear down and start replacing parts?

Tony

The only people who truly know where the edge lies, are those who have gone over.

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06-03-2009 08:24 PM  9 years agoPost 7
Olli-Pekka Mahrberg

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Finland, Joensuu

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Took the engine apart (once again), doesn't look too bad IMO. The rear bearing has some rust on it but feels smooth, front bearing is OK, cylinder pipe doesn't have any scratches. Piston and the head have some signs of lean run? Should I replace anything?

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06-03-2009 08:41 PM  9 years agoPost 8
JuanRodriguez

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The Villages, Florida

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The "critical areas" look pretty good to me !

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06-03-2009 08:51 PM  9 years agoPost 9
JuanRodriguez

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The Villages, Florida

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Tony,
I'm by no means an expert on the topic..... what I have seen from lean runs is that the aluminum piston expands from the heat to the point of contacting the liner.....from there, aluminum melts, transers to the liner and the scoring process takes place causing some pretty deep scratches. The attached pic showing the damage is not a TT 53 but the end result is the same....

I'm not sure if the lean runs can effect just the ring as you ask but it's cheap enough to just replace the ring if you suspect it may be damaged..... lightly hone out the cylinder with a brake hone and oil just to "clean it up" a little bit and then treat the engine as if it were new for break in purposes.....

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06-03-2009 09:25 PM  9 years agoPost 10
glydrjocky

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Livermore, CA - USA

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Thanks for the great info Juan.

Is the head on Olli's Redline somewhat discolored or faded from heat? Perhaps its just the lighting or the camera but mine is quiet a bit darker red as I recall. I read in another post that overheating changed/faded the head color.

The swirled color markings on the outer sleeve is normal and must be associated with some kind of case hardening or quenching process. Reminds me of an old case hardened six shooter.

I'm curious to see what will help bring this .53 back to its former self.

The only people who truly know where the edge lies, are those who have gone over.

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06-03-2009 09:44 PM  9 years agoPost 11
JuanRodriguez

rrProfessor

The Villages, Florida

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No problem, Tony.

I think the color in the photo may be due to the lighting..... Sometimes the anodizing process can produce different results as well so the color from one may not exactly match the next....

I'm also curious and hope that Olli will post back once things are sorted out....

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06-04-2009 10:04 AM  9 years agoPost 12
Olli-Pekka Mahrberg

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Finland, Joensuu

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Thank you all for your thoughts. I discovered something when I took the motor apart. It seems like the gasket between the carburator and the crank case isn't totally airproof, because there was oil between the parts. That surely will affect the mixture during flight. Has anyone had similar problems?

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06-04-2009 02:59 PM  9 years agoPost 13
glydrjocky

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Livermore, CA - USA

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I believe the gasket is a phenolic composite material to insulate the carburetor from engine heat absorbtion.

I recall reading not to over tighten the screws so as not to warp the carb housing and cause an airleak. I believe I used some blue loctite and took care not to over torque the fastners.

The phenolic gasket itself may actually absorb some oils on the surface but should be an airtight material.

Tony

The only people who truly know where the edge lies, are those who have gone over.

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07-02-2009 03:44 PM  9 years agoPost 14
Olli-Pekka Mahrberg

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Finland, Joensuu

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Hi guys, nothing made any difference, the engine stil leans out occasionally. Changing the piston liner could help but I think won't bother to do that bacause I'm going to move to 90s any time soon..

www.olli-pekkamahrberg.webs.com

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