Water in Gearbox Oil

[deako1037]

Hi, I'm looking for a bit of help/advice please, my friend has bought himself a secondhand 2000 YZ 125, when we did a oil change on the gearbox we found the oil to be grey/milky. We drained the oil and an threw in some fresh stuff. The bike was then left without being started for approx 12 hours. On checking the oil again after this period it was again the same grey colour (eliminates clutch wear). I have checked the radiator fluid levels and they appear to have dropped, would this be something like the water pump gasket leaking ? I own a 4 stroke and have no experience of 2 strokes. If that is the only or most likely cause for the water to get in, is it an easy job to fix and if so could someone give me a very brief description of how as we have no manuel with this bike.
Thanks for reading and for any help :cool: Deako

 

[reelrazor]

It could very well be the waterpump seal. There should be a weep hole on the case right below the waterpump(on the housing-rather tiny hole). If the seal has failed you should be losing coolant there also(that is why tthe weep hole is there, to be an indicator of the seal's integrity). I am not sure on that model, but usually there are two seals behind the waterpump impeller, one holds coolant on its' proper side and trans oil on its' own side. The weep hole will be between the seals. It is a fairly easy job to change the seals, but I wouldn't try to do it without removing the right side case cover(the inboard(oil) seal is usually installed from the inside).

Another possibility is that the waterpump housing has eroded and is now porous. This will necessitate replacing the housing/clutch cover.

Your overnight 'test' of the trans oil is good thinking, but unless you let the old oil drain for that length of time as well(at least), it isn't very conclusive. The clutch pack alone holds back a signifigant amount of oil.

 

[deako1037]

Reeelrazor, thanks for the reply lots of good points there., Just for your info, I did let the oil drain over night before I refilled it so I guess it sounds pretty certain that we have a leek somewhere around the pump or as you so say an eroded clutch case.
Many thanks Deako

 

[uts]

Sounds like a leak in the actual water pump (clutch case) rather than a seal as realrazor suggested. Both the oil and water seal would have to be gone and the fluids would more likely leak out the inspection hole (weep) than enter the other chamber. My CR250 had the same problem. It was a design fault with the model. I bought a new clutch cover for $280 (Aus) and within 2 months I had the same problem. Honda were willing to replace it for me but it would have just kept happening. So I coated the inside of my water pump with an epoxy called Devcon plastic steel. This works great. Every 20 hours of use I remove the water pump cover and touch up any devcon spots that need it. I do have to flush the cooling system regularly though because the devcon slowly chips away, but nowhere near as fast as the metal was. This is the cheapest way to fix it, but if you can afford it I would replace the part.