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darksun27

Yz water pump seals

14 posts in this topic

Allright, about 6 months ago my yz 426 water pump seals started to leak a little bit. I let them leak for around 2 weeks hopeing it would stop, and it didnt. I then researched and found out i needed to replace the shaft, bearings and seals; so i did before i went on a big ride. then they started leaking again at the end of the day :thumbsup: maybe i put them in backwards :thumbsup: but neways im gettin tierd of filling it full of antifreeze everytime its rode and ive got a harescramble race coming up so i orderd a new set of seals and a shaft hopeing it will maybe fix it this time. so my question is which side of the seals need to be facing in/out? or what am i doing wrong to make the seals leak when im replacing them? ohh and btw 1 side of the seal is solid and the other side is open with a spring on the inner diameter of the seal.

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the open or spring side as you call it always goes inward and the flat surface side always out, facing you. it is important that you use a seal driver or a socket of the right size when installing seals so you dont run yhe risk of damaging the new seal. also lubricate the inner edge of the seal before installation so it wont try to crimp or fold on you. and only drive the seal on as far as needed, dont try to drive her home all the way with one wack.

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The strength of the seal needs to be facing the fluid it is sealing, and in this case, that is the coolant in the water pump. The lip with the spring on it should face the impeller, which makes it look backwards by most standards.

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When I bought my used 450f, the water pump leaked. When I removed the impeller, I saw that the previous owner had installed the water seal backwards. I put a new seal in as Grayracer says, with the lip and spring facing the wet side (impeller). The water pressure around the impeller helps hold the lip tight on the shaft. My water pump has remained perfectly dry for a dozen rides now. The previous owner was supposed to be a pro racer getting a factory sponsorship. The owner's manual doesn't show the detail very well on the seal, so I can see how he made the mistake.

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so the side with the spring on the lip faces the fluid? so the water pump seal with the lip and spring faces the impeller side, and the oil seal with the spring and lip faces faces the motor. right?

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how do you know which seal is leaking?

Can you replace the first seal without removing the crankcase cover?If oil seal #2 was leaking there would be water in the oil right?

I guess i,m looking for shortcuts

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there might be water in the oil but they designed that little peep hole between the seals to keep that from happening

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how do you know which seal is leaking?

Can you replace the first seal without removing the crankcase cover?If oil seal #2 was leaking there would be water in the oil right?

I guess i,m looking for shortcuts

I am going to guess that most of the time only the water seal is bad and the shaft and oil seal are good. That was the case on my 04' 450F.

Even though the way I repaired mine is not Grayracer approved, what I did was quick and easy.

1)remove the water pump cover after draining coolant.

2) put bike in gear and apply the rear brake.

3) put a socket wrench on the impeller and tapp the ratchet handle with a hammer with quick, but non-powerful taps to loosen the impeller.

4)once the impeller was off, I pried the old water seal out with a very small flat screwdriver being careful not to damage anything.

5) install the new water seal with the lip and spring facing out towards the impeller, (wet side).

6) torque the impeller back on to the spec and replaced cover.

7) refill with pre-dilluted Yamacool coolant.

8) rode the crap out of it for the next 14 trips, no leaks. :bonk:

Some say that you can bend or break off the impeller drive shaft doing it this way, but I got away with it by being careful and using my wrench tapping method to get the impeller off. Grayracer would say this :thumbsup: But I say this :thumbsup:

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HIJACKED!!!!! Sorry for this, but just out of curiosity what is the Grayracer approved method for removing the impellar??? Thanks,

Josh

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HIJACKED!!!!! Sorry for this, but just out of curiosity what is the Grayracer approved method for removing the impellar??? Thanks,

Josh

Here's what I found from Grayracer.

You should not attempt to remove the impeller from the w/pump shaft while the case is still mounted on the engine. Doing so puts all of the torque load on the drive tab of the shaft, and you will very likely break the tab off if you persist. With the case removed, you will find a set of flats on the inboard end of the shaft that you can use to hold the shaft with a wrench while unscrewing the impeller.

Note: the impeller will not come off easily, and a little heat and/or an impact wrench is useful. It is a normal, right hand thread.

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So, on suspension linkage (sorry that this is a little off topic) does the lip of the seal with the spring face outward or inward toward the bearings?

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To add to my previous post, if you look on thumperfaq in the greasing suspension section, the picture of the relay arm shows the seal with the lip and the spring facing outward.

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how do you know which seal is leaking?

Can you replace the first seal without removing the crankcase cover?If oil seal #2 was leaking there would be water in the oil right?

You'll know which seal leaks by the fluid that drips out. They don't mix because, like the man said, there is a void space between the seals that vents out through the weep hole, so that neither fluid that passes its seal can reach the other one.

As I was quoted above, you can remove the seal with the cover on, but you can snap off the shaft doing that, and you can't inspect the shaft for a groove worn into it by the seal. Coolant doesn't lube as well as oil, and the coolant seal will often groove the shaft deeply enough to cause the new seal to fail early, or possibly not seal at all. Just do it right, it's not that big a job. Run the bike for a minute first so you don't need to drain the oil (unless it's already time for a change)

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