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58Pro Crankshaft Front bearing Seal problem

Old 03-08-2008, 07:15 AM
  #1  
glofuel
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Default 58Pro Crankshaft Front bearing Seal problem

Hi Guys, Just for reference to anybody having starting/running problems and have checked all other possibilities like cleaning the carby etc, I had a problem which caused the engine to keep dying then would not start at all. This is the cause....

I placed thumb/finger over carb intake to find no suction at all when turning over engine by hand (make sure ignition is switched OFF), but noticed air being sucked in through the front crankshaft bearing Oil Seal behind the prop driver. Dismantled engine to remove Oil seal and discovered that on the rear side/inside of the seal the long thin round spring which wraps around the centre to keep tension on the crankshaft had popped apart and just laying in the groove of the seal itself.

If you have the same problem and decide to rectify this yourself, beware the front end of the crankshaft which holds the prop driver on, is a Left hand thread which needs to be undone using two nuts threaded on to the shaft and tightened against each other.

No need to dismantle engine compleatly but it will need to be removed from aircraft so as to hold the prop driver in a soft jaw bench vice to undo the shaft using a spanner. Don't forget to put a small amount of thread-lock on before re-assembly.

The Oil seal and bearings are standard sizes which should be available at any good bearing supplier, if you decide to change the bearings aswell as I did make sure you use good quality bearings.

But don't attempt this unless you are confident at dismantling without causing any damage, otherwise send it back to the supplier for service.

Ian

Old 03-08-2008, 12:48 PM
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pe reivers
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Default RE: 58Pro Crankshaft Front bearing Seal problem

are you talking about a NVVS 58 prosport? There is no left thread up front!
While at it, replace the front bearing with a double lip seal bearing, and use a filler ring where the seal was. The double lip seal bearing is lubricated for life and seals well. This way you will not have to rely on whatever little oil will find it's way up front.
If you use a seperate seal there, a drop of oil every now and then to lubricate the seal will do the trick as well.
Old 03-10-2008, 07:37 PM
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glofuel
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Default RE: 58Pro Crankshaft Front bearing Seal problem

Pe, Sorry, Yes you are absolutly right, as usual, it was the thin retaining nut that holds the bottom end of the conrod to the crank which is a left handed thread.

Ian
Old 03-11-2008, 10:17 AM
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pe reivers
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Default RE: 58Pro Crankshaft Front bearing Seal problem

Right. It's the crankpin nut that is left.
Still remains the need to lubricate the front seat if you replaced it. I too run an early type 58cc engine. When the front seal starts groaning and shows increased resistance, It is time for a drop of oil.
Current engines have lubrication nipples up front, or have double seal bearings which do not rely on external oil supply.

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