2021 EGL A17 NC250/300 Coolant in oil.
 

I recently purchased a very clean low hour EGL A17 300 with the Zongshen NC engine. While doing my typical new to me bike maintenance I found coolant in the oil. The previous owner told me that dealer had changed the oil a couple of months ago and bike has less than an hour ride time since. I have searched for information and cannot find anyone else mentioning this issue. I am going forward with water pump shaft and seal replacement and hoping that this resolves the issue but was also looking for guidance on other possibilities while I am tearing into it. Bike did not white smoke or run poorly. Thanks

Have you run a compression check? I'd start there before tearing onto it too far.

I have not, but I certainly can, however the bike starts and runs perfectly, and I see no evidence of it burning coolant.

You seem to be on the right path with the seal and shaft repair. I’m thinking no air in the coolant tank while running. That would make me think no head gasket problem. It does seem odd that the bike is not very old? Just my thoughts…

Update: Every NC250 parts breakdown I have found shows a simple single lip oil seal and a similar water seal. Mine has a mechanical seal like the NC450. The seal is in several pieces. I am not sure where to go for parts. Is this an NC450 seal? Is it an updated NC250/300 design? Perhaps it was a factory screw up and the NC450 seal was used by mistake? I am having a hard time finding a reliable source.

Are you 100% sure it's coolant and not just condensation?

Have you contacted CSC? They're probably your best contact for info and parts.
It's almost sounding like some ham-fisted mutant young kid did the service at the dealership and maybe didn't service it correctly??????

Update. Replaced water pump mechanical seal and problem persists. Trying to resist the urge to put some K-Seal in it, but head and base gasket on order. Just an FYI for anyone who might order a new pump shaft, Install it in exactly as you found it. My replacement shaft had additional washers and snap rings that had to be removed to make a proper seal.

I assume you’re not getting bubbles in the coolant? Why I ask is it could be from a pinhole leak in the water jacket after all where was it built. If this was the case a sealant of some sort would be the only best bet for temporary or perhaps longer relief. Just thinking out load…

I have never used K-Seal in a bike, but I have used it in several cars / trucks and it has worked EVERY TIME. Worth a shot, IMO.

k seal never worked for me.