Is my water pump failing, 2013 yz450f? Pictures added!

So, bike had been sitting two months and I dont remember starting it inbetween that time. My bike has only about 60+ hours now and that is pretty low hours imo considering it has not been raced hard. More like bike had sit on the garage too much and not ridden regularly.  Temperatures are around +5- -3 Celcius degrees in my garage. I started it yesterday and noticed this:




I started it today again and it gave a drop of anti freeze again...



It does not seems to leak when it just sits but when I start it. What is the next step with this? Buy whole repair kit, which includes what?



I read that failing waterpump/Shaft is typical failure with Yamaha. And it usually is due low quality water pump shaft(lame for yamaha not fixing that after all these years)...



Anyone heard of this? Cycra sells this and they say it has hard coating on it, which is harder than the OEM shaft surface and no more worn and scratched shaft which usually cause the seals go and leakage from the weep hole.

Edited by KTMfinrider

The fault is probably with the outer of the two seals (the coolant seal) alone.  What you are likely seeing is that the seal has hardened a bit so that it gets too stiff to work in the cold.  But, the shaft could be at fault, too, of course.  


The Cycra shaft seems like a good idea, although I haven't ever used one.  Haven't had any real bad luck with the OEM shafts.  When replacing the seals, the best practice is to replace both the inner and outer (oil and coolant) seals and the shaft bearing.  Review these two posts:

GrayR, i just took the bike for short ride. I only wanted to get engine on operating temperature. So I rode like 20 minutes after warm up and came back to garage inspect of any leaking is showing... and guess what, not one single drop anywhere. When I said earlier started it yesterday and today I only let it run on stand like few minutes. But now I had proper test ride.

I dont get it, is seal or what ever worn just a little bit and when the engine has not been running for some time it kind of oozes there some Antifreeze which spits out from weep hole when waterpump shaft is turning, engine running?

When i bought the bike year ago it had only 20 hours in it. It had sitting like year in first owner garage and not being used. I remember few drips antifreeze then also around weep hole. But after I got the bike and it was ridden regularly there wasnt any signs of leaking anymore.

What i am trying to say can seals kind of shrink when bike is sitting in rather cool temperatures and not being run? And which let liquid get through the outer seal?

Bike has had same anti freeze for 3 years since new and hasnt lost a smallest amount it when i have been measuring the level from radiator cap.

Sry for poor english. im not much of story teller.

Edited by KTMfinrider

That's OK, my Finnish is horrible. :smirk:


As they age, water pump seals will often do this sort of thing.  Once they start leaking, they can leak while the engine is cold and not running, cold and running, hot and running, hot and not running, and they might leak in any one of those conditions only, or a couple of different conditions, or all of them.  Spinning the shaft can either help the seal hold because the coolant lubes the seal and helps it, or it can make it leak.  It's almost like the seals have a mind of their own.


After they get used a little, they may stop for a while if not stored for a time, but they always end up leaking again once they start to fail in this way.  The thing to keep in mind is that you only have a bit over one liter of coolant between you and a seriously damaged engine, and you can lose it to a small leak in a very short time.


I suggest you "bite the bullet" and just fix it.

Why risk it?

I replaced mine with a hotrods rebuild kit for like 20 bucks. I missed a planned day of riding over but was glad it didn't totally let loose in the middle of the woods and trash the motor.

Yes guys I ordered new seals both of them and new bearing and waterpump cover seal paper. That said now when I have been checking it ever since I noticed the leak week ago there has not been one single ddrop of coolant coming out from weep hole.

But I will open clutch case and inspect seals and shaft too.

If shaft has grooves, buy new OEM one or that cycra or can that old shaft be honed? :D

Whether you can successfully polish the shaft depends on how much damage has occurred. I've done it before and had it work. Chuck the shaft up in a power drill and hold a piece of 320 grit around the wearing portion while you spin it. If you can get to where you cannot feel the mark the seal left with your fingernail it will probably work.

One more question...

Gray, I was offered with half of the price of OEM Hot Rods kit for the water pump. Good or bad?


I am asking because it was so cheap I might buy it for spare parts box.

One more question...

Gray, I was offered with half of the price of OEM Hot Rods kit for the water pump. Good or bad?


I am asking because it was so cheap I might buy it for spare parts box.

I have seen a lot of Hot Rods waters pump shafts installed without issue.

Don't know anything about them for certain. 

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