Coolant leaking from crankcase
Posted April 10, 2013 - 01:41 PM
Bike Yamaha WR400F 1998.
Posted April 10, 2013 - 02:23 PM
It is there to let you know when the impeller shaft or impeller seal are wearing out.
If the bike sits for a long time, the seal becomes less compliant, letting it leak.
It usually goes away, or becomes minimal with use.
READ YOU SERVICE MANUAL
Posted April 12, 2013 - 09:49 AM
Ironically, this has happen after the winter lay up, and it was fine when I put the bike away last year
I decided to replace the seal, as I didn't want it to fail mid race, dump all my coolant and the engine seize
You don't even need to remove the clutch cover to replace the leaky seal (well at lest on the 450 you don't, don't know about the 400)
Drain the coolant
Remove the water pump cover (no need for a new gasket, as its sealed with an o-ring and hence is re-usable
Undo impeller with 10mm socket - its a normal RH thread
Remove impeller from shaft
you will now see the seal that is the cause of the coolant leak
Lever the seal out with a screwdriver or similar
To fit new seal, lube with grease the ID and OD of the seal (OD of the seal so it will slide back into the housing with minimal effort, ID so it lubricates the seal in use)
Press back in with fingers/thumbs, with numbers on the seal face, facing inwards
Refit impeller and torque to 14Nm - use a bit of locitie on the thread
Refit water pump cover
Refill with coolant
Start engine and check for leaks
No more than 30 mins start to finish
Edited by GuyGraham, April 13, 2013 - 02:09 AM.
Posted April 20, 2013 - 04:12 PM
Posted April 22, 2013 - 08:32 AM
This stops the impeller shaft turning when undoing the impeller