'99 400 Leaking coolant


I just picked up a 99 WR400. I was idling it out in the driveway today when I noticed that there is a steady, but very slow dipping of bright green coolant dripping off the bottom of the engine case. I'd say one drop every 15 sec or so. I went around all the 8mm bolts on the waterpump side of the engine and tightened a few of them. It's still dripping. Any sugestions on where to look to find the problem? Are the water pump gaskets prone to failure on these bikes? Other than that, this bike is in great shape. The oil was clean and full and there is plenty of cooant in the overflow tank (it only seems to drip while running).

That's the water pump seal.

Ride it a bit and see if it stops. mine leaked 3 yrs ago ..stopped and never restarted.

Are you sure it wasn't leaking from the coolant reservoir overflow? How hot did the motor get while idling? These bikes do not like to idle too long. I recently found a few green drops of coolant on on the florr. I also have a 99 WR 400. As it turned out however, it was from the overflow. I am also in MA. Where are you located?


There aren't really any water pump gaskets. But there are seals around the impeller shaft. (1 oil seal and 1 coolant seal.) I have replaced the seals and impeller shaft on my '99 twice over the past 6 years. It's not a big job- drain the coolant, take off the right side cover, replace the seals and the right side cover and refill the coolant. It should take about an hour of your time and you will need to purchase the 2 seals, 1 side cover gasket and one impeller shaft for a total cost of less than $50 if you shop around. I list the impeller shaft as a replacement item because I have replaced just the seals and it has still leaked. Then you gotta do the whole thing over and may need to get another side cover gasket because the new gasket is now used. The shaft gets worn around where the seal contacts the shaft, which is another cause of leakage.

Don't ignore this because in my experience, they don't fix themselves and the peace of mind is worth the $50. Tightening bolts will do nothing to this problem.

when you say remove the cover, is it the small water pump cover (like 3 bolts or something) or the entire big right side cover (around 10 bolts)?

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