oil and water are not mixin' for me!

Hey folks, lookin' for some feedback.

I have a 98WR400, just bought used, and each time I go out for a ride I have to top up the water and the oil. In 60 miles I will burn enough oil to drop the line from the top of the full range to the bottom of the full range on the dipstick.

The only oil leak is from the oil breather hose and this is just the occasional drop that I see after stopping the bike

WRT water, each ride I go on I have to add at least half the amount of water that it takes to completely fill the rads. On occasion I have seen water coming out of the hole at the bottom of the water pump...I assume this is the overflow.

Is this normal to have to add so much oil and water?

No this is not normal! Is your bike running hot ie boiling water in the overflow resovior?? could be a radiator cap problem maybe have it pressure tested. The 98 models have a problem with the water pump shaft hardening/plateing/anodizing. It was fixed for 99. If you start seeing water coming out the weep hole on the bottom of the water pump then the seal and or shaft have warn and need repacing. Use the search function and a key word like "water" and it will find several posts that address this issue and tell you how to replace the water pump shaft with the updated 99 part and both seals.

A head gasket leak can also empty the radiators right into the cumbusion chamber and straight out the exhaust. Bryan had this problem earlier.

As to the oil could be rings, valve seals, head gasket or a leak. Would need more info. Keep us psoted as to your progress.

Hum head gasket and a bad water pump shaft would be my guess for starters and investigation good luck.

Keep us posted on your progress.


The hole at the bottom of the water pump is where the water drains when the impeller shaft seal(s) are leaking. There are two seals on the shaft. The inner one has engine oil behind it and the outer one has coolant behind it. The drain hole leads up to an empty space between the two seals. You need to update to a '99 impeller shaft and change both seals. That will fix your water leak. As far as the oil, if the oil seal there is leaking as well then that will fix that too. Once you fix the seals if it's still losing that much oil then you'll have to figure that out at that time. I know on my bike if I fill it to the top line it'll lose some out the breather hose, I usually fill it halfway between the marks and it never uses any. I suspect you're losing some through the same spot as the coolant and just don't realise it...


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First things first, did you know that you have to run the bike just before you check the oil level? If you don't, the dipstick doesn't read right and you'll over-fill (like I did).


What about the head gasget.

Thanks for the feedback guys. Now that I know what I am looking at and for it is clear that there is a steady and slow leak from the hole at the bottom of the water pump. I have ordered a new impeller shaft and seals and will change them next week. I can detect no oil in the water leak, however, there is always a few drops of oil from the breather hose after a ride. This alone could be the cause of my very slow loss of oil. Is it normal for a small amount of oil to drip from the breather tube on a regular basis?

Hey trent:

I don't consider myself as any type of expert on the WR but I have been on a fairly steep learning curve since I bought one. Regarding the breather hose oil leak, I found that mine blew oil out this hose as I was not filling the bike with the corrct amount of oil. My bike is incredibly hard to get the oil to the right level on the dip stick as it had to be run for a few minutes before the oil completely pumped up to the header tank in the frame. I now just measure out the correct amount of oil in a large measuring beaker and then pour that amount into the bike at every oil change. After doing this, the bike never leaks a single drop from the brether hose. After doing this I routed the breather house into the air box as I have sunk the bike a couple of times and found that the breather hose sucked water into the engine. It seems to me that having the correct amount of oil in the bike has stopped oil dripping from the breather hose. Also, I now check the oil as soon as I have finished riding and the level is always right on the full mark. By the way, when changing the oil, I try to let it completely drain out for at least a day before replacing the drain bolts and re filling. What I have just explained is probably very basic stuff that you already do, or perhaps even absolute bullshit as like I said, I am still on a very steep learning curve.

Originally posted by Trent:

Is it normal for a small amount of oil to drip from the breather tube on a regular basis?

Yes, this is normal. I think GB and Gil may be onto something as far as you topping off oil before every ride. Unless you run your bike for a bit the dipstick reading is useless, so you may have been overfilling with oil. I made the same mistake when I first got my 426 and overfilling seemed to increase the amount of oil blown out the breather.

I change the oil, check/change filter every few rides and measure out about 1.8 quarts and pour it in. Then I may check it while riding a few times.

I consider a small amount of oil coming out of the breather to be a good sign 'cause it indicates that your valvetrain is well lubed.

As for the water, these bikes run a bit hot (even 426 w/ larger rad) and tend to loose coolant out overflow. So even after you fix pump seal you need to check coolant level periodically.

Don't be discouraged, you bought a great bike. You just need some time on the learning curve like GB said.

[This message has been edited by Hick (edited 08-03-2000).]

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