Howdy from Tokyo!

I noticed if I don't run my MC28 for a while (few months) there *might* be a drop or two of coolant that drips from the water pump weep hole when I first crank it over.

I cannot get it to drip at any other point. Never drips while riding or after riding. Coolant level is solid.

I asked two local guys. The first said not to worry as pressure may build up from sitting and in temperature swings. Second guy said one drop is too many and could be a sign of seal failure.

The engine had a complete overhaul a few years ago with only a few thousand km's since.

What is the general view on a drip or two from the weep hole only on start up after a few months?

Dana
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2016 Husqvarna 701SM
2021 Husqvarna FS450 supermoto
1995 NSR250r MC28

If you look in the service or parts manual you will see there are 2 seals on the shaft, one for the water, the other for the oil. The weep hole is from the area between. Guessing you know this already. Most important is that you're not getting water into the transmission. Maybe drain the oil and check for water. If there is water in the oil I would change the seals. If no water then I would just make sure you monitor the situation close. Either way you should plan to change it at some point. If your bike has a wet clutch you can inspect and replace the clutch plates as well while in there. You'll need to replace a few gaskets while doing this work. Water pump cover and clutch cover, all available. Water pump shaft and seal kit also available. The plastic gear on the water pump has been known to crack but I think Andy will say they generally don't break. T2 racing makes a metal replacement..if you get to that point.

I worked on a friends Moriwaki MD250 last year and we had same issue, the bike has a 4 stroke dirt bike motor. The set up is very similar to NSR. In the Moriwaki case, the water pump shaft had worn and was actually causing the leak out the weep hole, no water into the crankcase. I replaced shaft and seals. We also needed new clutch basket which what prompted me working on bike and I found the water leak while inspecting things.

If I remember correctly, you don't need to pull the engine to replace the seals. But it does take some effort as the seal gets destroyed when removing it.

I appreciate the response!

No water was present in the oil.

I did buy the T2 rebuild with everything, including new shaft with the gear.

By the looks of it, the mechanical seal is the hardest part of the replacement.

Dana