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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › OS37 not able to take conrod out - strange plastic "piston pin retainer "
10-24-2011 05:59 PM  6 years agoPost 1
frasencirrNovice - Chile - My Posts: All  Forum  Topic

Hi dears,
in following procedure to replace the engines bearings , I got stuck not been able to get the conrod out. The conrod gets halve way out but it is not slipping at the piston ring.Instead, the piston ring slips out of the piston . I have put lots of WD40 to it but seems to not get loose. In looking closely I have discovered a strange " plastic like piece , gray color " coming out of the piston where the piston ring sits, ( piston pin retainer ) . It is not moving.

Please help , I am attaching pictures where the " gray color plastic piece is to see " It is an almost new engine.

Thank you very much
Greetings
Francisco

The gray color piece seems plastic and sits at the end of the piston ring , it moves as I slide the conrod.

What is this gray piece ? The retaining clip is supposed to be mettalic.

I am going to miss that glow smell .....

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10-24-2011 06:19 PM  6 years agoPost 2
Lamar Cooley

rrApprentice

Houma,La.,U.S.A.

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os 37 con. rod
frasenci
This engine does not use the typical "wire" ring to retain the piston rod. These plastic disc's act as the retaining ring.
They (I believe delrin) make contact with the cylinder walls.
Looking at the pictures one of the disc's has moved into the cylinder area and is preventing you from being able to move the piston over that little bit of extra you need to get the con.rod off the shaft.
You will need to get this disc back into the piston rod hole. Then you may be able to move the piston enough to remove it.
I hope this is of some small help.
Regards


Here when wanted.
There when needed.
Everywhere when looked for.

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10-24-2011 07:46 PM  6 years agoPost 3
airdodger

rrElite Veteran

Johnston USA

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You need to slide the piston to the cylinder wall, next slide the rod all the way to the side, the rod should just clear the crank pin. Use a heat gun if the rod will not slide.

Chris

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10-24-2011 08:51 PM  6 years agoPost 4
frasencirrNovice - Chile - My Posts: All  Forum  Topic

Thank you both very much !

@ Lamar Cooley

In looking into de OS parts list for this engine, it clearly shows the traditional spring type metallic retainer . Ok , maybe it is an recent upgrade from the factory ?? Anyway , at moving the conrod into wanting to take it out , the pin and the plastic retainer both move. Its is clear to me that the conrod is stick to the pin on that side. I can freele , from the plastic disc side, return it into the piston area....

@ airdodger

I will try heat, I am sure the pin is sticking to the conrod on that side.

http://downloads.hobbico.com/evpl/osm/ev14000aa.pdf

Some surprise to see an plastic retainer hwe !!!

Any clues on how to handle the sticking pin ?

Greetings
Francisco

I am going to miss that glow smell .....

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10-24-2011 09:30 PM  6 years agoPost 5
airdodger

rrElite Veteran

Johnston USA

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Just clean the pin up when you have the engine apart. You could use steel wool or the plastic type, like a scotchpad. Chuck it in a drill and clean away. If you are burning oil on the pin the engine is running too hot, unless you are using castor, that can build up.

Chris

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10-25-2011 04:24 AM  6 years agoPost 6
Lamar Cooley

rrApprentice

Houma,La.,U.S.A.

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os 37
frasenci,
airdodger has it right about moving the cylinder towards the back.
But if as you say the con.rod is "stuck" on the wrist pin.
Then you may want to try this. Move the con.rod back to it's original position in the cylinder. This should then bring the wrist pin and plastic button back into the piston. If I recall correctly this is a small plastic disc and may come out when you move the con.rod and wrist pin back to it's original position. (However this button may have a stem on it that actually goes up into the wrist pin
like on the Thunder Tiger engines.) Turn the crank shaft to bottom dead center. Get a piece of hard wood that will fit between the cylinder and cylinder wall. Place it in the engine at the plastic button. With the piston as far down as possible you may then be able to grab the con.rod at a higher position and get the con.rod to slide
a little more on the wrist pin. Clearly, there is no wrist pin retainer ring on the button side of the cylinder or it would not have moved out of the cylinder when you shifted the con.rod. I seem to remember that there were 2 of these discs and no retainer rings on my os 55. Did you notice if there was a second plastic disc on the other side of the piston ?
I hope this is of some small help
Regards


Here when wanted.
There when needed.
Everywhere when looked for.

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10-25-2011 03:57 PM  6 years agoPost 7
frasencirrNovice - Chile - My Posts: All  Forum  Topic

Boys , so far I have tried evey possible trick. Will not do.

I think however, I could have found the problem , that is the cranckshaft is not sitting at the right position, : It should be more farther to the nose and I can explain it in looking at the hole in the shaft at the carburetor port...... shouldnt it be all the way exposed ?

Please comment

It seems it could go 3 mm more to the nose ....

Thank you again
Greetings
Francisco

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10-25-2011 05:40 PM  6 years agoPost 8
Lamar Cooley

rrApprentice

Houma,La.,U.S.A.

My Posts: All  Forum  Topic

os 37 con. rod
frasenci
That would certainly explain the problem. In looking at the photos of the crank case inside. It apperars that the crank shaft has moved back. Pull on the front of the crank shaft at the threads or push in from inside. To assist, you could put a spacer on the front with the
prop nut to hold the crank shaft in for you.
I hope this is of some small help.
Regards


Here when wanted.
There when needed.
Everywhere when looked for.

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10-25-2011 06:26 PM  6 years agoPost 9
Four Stroker

rrElite Veteran

Atlanta

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Make a wood screwdriver out of a chopstick. Heat the engine in the over to 300F. Shove the piston to the rear. Remove. Don't burn your fingers.

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10-30-2011 12:59 PM  6 years agoPost 10
frasenci

rrNovice

Chile

My Posts: All  Forum  Topic

Please Help !! No such OS-service around here -----
I tahnk you all for your efforts.
Believe me , I have tried. This is absolutely NOT the first RC engine I took apart in my 25+ years of hobby......

Will not do. De freaking conrod does not get free.

I am thinking of try taking out the plastic retainer ???

Hacksaw the Conrod ?

I do not even can put it all back together because in this circumstances I can not identify the mounting point for the Piston ring , so the sleeve can not go in.

Oh my....

Will fly my old trusty OS 32 SHX , now THAT is an Heli Engine !! I have had a few.

Please , any OS representative out there ?

Yes , if you read my signature, I have already made the whole investment to fly E-Heli. 600 and 450 . Even transformed an 32 Hawk Pro to E ( diy ).

Although I like engine mechanics,........
But this 37 is practically NEW.

Thank you
Greetings
Francisco

I am going to miss that glow smell .....

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