VIRE 7/12 Crank SEAL (3)

Common Faults & Additional Info

Will need replacing if they loose sealing ability (if the engine overheats or rusts, the lips weld/roughen and the springs rot inside) and if you are replacing crankshaft into crankcase generally (e.g. rebuild/replace bearings)

If you are replacing main bearings, then you should always replace these.

The Vire 7&12  still allow salt air into the crankcase, to corrode inside like any marine 2-stroke, and condensation-pumping will do the rest if the engine is not run for weeks.

When the seals fail - you could get 2 problems:

  1 petrol (the gear/aft end heats up more than the flywheel/fore end) seeps into the gearbox.

  2 petrol seeps into the flywheel/points get dirty - also slight loss of compression/power.

Check to see if your Vire has deteriorated seals: remove points inspection cover/ flywheel: if there is any oil dribbling below the points/ignition plate, it is a sure sign.

If the front main bearing is rusted, it is quite likely it has a leaking seal too. 

There is little point replacing seals onto a rough or pitted shaft.

Seal lips and springs have to point towards the pressure/piston.

On the Vire 7 the third seal faces the gear oil.

Easy to fit the front one with the crank out.

For any further assistance please contact me.