HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Grieby54

Need help fast! '03 YZ450F leaking coolant

7 posts in this topic

My riding buddy and I are going riding tomorrow and we've been working on his bike all night trying to get it in tip top shape. Well, we decided to replace the coolant. So I took the bottom bolt out of the water pump, drained the coolant, replaced the bolt, then added new coolant. I wasn't paying much attention to if it was leaking before or not, but I tipped the bike sideways to get the coolant in the left side radiator as well, then when I returned to the right side, I found coolant dripped out of a weep hole on the bottom of the water pump. What's the deal and how do I fix it???

Share this post


Link to post
Share on other sites

Coolant is tricky stuff. The first thing to ask is whether it's really still leaking, or if it's just kind of left over from stuff that ran across that surface when you drained it?

But if it is really leaking from the weep hole in the case, or appears to be, first be sure there's still a copper washer on that bottom bolt you had out. Then, you get the bad news.

A leak from the weep hole is caused by a failed water pump impeller shaft seal. The hole is the outlet from a passage designed to release coolant leaks to the ground rather than let them get into the engine oil (or vice versa), and it means you need to replace the seal, and possibly the shaft, if the seal has worn a groove in it. That means pulling the right engine case cover off.

But you might try running it. Water pump seals may leak when cold but not when warmed up. If you keep a careful eye on it, you might get your ride in. But ALWAYS bear in mind that it's dangerous to open a hot cooling system. Let it cool a little before you check the level.

Share this post


Link to post
Share on other sites

Thank you very much grayracer. (I'm Grieby's riding buddy, and owner of the ever problematic bike)

The weep hole is where the leak is coming from, and its fairly slow and steady (as it, drip.... drip.... drip... etc). I will try warming the bike up before I ride tomorrow and pray that it will at least work for the day. If it is still leaking, I can always just keep adding coolant throughout the day right? I'm not sure how practical this is (whether or not I will go through to much coolant trying to keep it full) but I really need to ride tomorrow.

Thanks again for the help! :thumbsup:

Share this post


Link to post
Share on other sites

The same thing happened to my 99 YZ400F and it stopped when I replaced the seal that was spoke of in an earlier post.

the seal should be cheap but the shaft may be a bit more costly. Just do the seal replacement and it should fix your problem.

Good luck!!!!!

Patrick M.

Share this post


Link to post
Share on other sites
The same thing happened to my 99 YZ400F and it stopped when I replaced the seal that was spoke of in an earlier post.

the seal should be cheap but the shaft may be a bit more costly. Just do the seal replacement and it should fix your problem.

Good luck!!!!!

Patrick M.

not necessarily. If the shaft has grooves on it ...no seal by itself will repair it. The shaft and the seal are pretty cheap - 20.00-30.00 max.

I replaced both on my 03 when it did the same thing:thumbsup:

Share this post


Link to post
Share on other sites

Is there any chance that water could be getting into the motor through this leak? We didnt have the bike running for long, but it seemed to have alot of white smoke (my dad says he saw it comming from the exhaust , but I know there was quite a bit comming from the water pump area).

Share this post


Link to post
Share on other sites

The way the pump is designed, there are two seals on the shaft, one for oil and one for water. There is a space of about 5-7 mm between these seals, and this space is open to the outside by means of the weep hole where your leak is.

When everything is working as it should, the answer is no, it can't get into the engine. Even if it did, it couldn't get to the combustion chamber. That would take a bad head gasket or similar problem. Also, the oil would take on the appearance of a sickly looking vanilla milkshake if there were coolant in it.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0