Swamped my '99 WR 400

5 replies to this topic
  • kjr247

Posted March 25, 2008 - 04:54 PM


Have I missed a thread???

A couple of weekends ago, I decided to take the WR swimming. I went through a stream that happened to be almost 4 ft deep and did not have my airbox snorkel on...:bonk: Needless to say...it did not like it a bit. I have got a bunch of water in the crank case. Got it started (after getting pulled by a dreaded (but very nice :prof: ) 4 wheeler 2.5 miles up a mountain), at home pulled the plug and changed the oil 3 times... but it is still real milky.

A friend told me to let it sit a week and the oil/water will separate...nope. Still a perfect emulsion.

What needs to be done...keep changing the oil? I am cool with that but I do not want to keep the water/oil emulsion in there too long. Am I harming things? Crack the motor...experts please? KJR

  • matt4x4

Posted March 26, 2008 - 04:16 AM


You didn't state that you pulled the oil filter and drained out all the external lines etc, so my assumption (hopefully) is that there is/was still plenty of water left in places that don't drain very well/fast.
Whenever I swamp a vehicle, I tend to drain the oil, fill it, run the vehicle for 1-2 minutes (no load), immediately drain it again and fill it and run it and drain it and fill it and run it for 2-5 repeats, this usually removes 99.9% of what was in there, change the filter and you should be good.
If you continue to get milky oil, you may have done some other damage like a blown gasket or cracked head and are now getting a coolant leak into your oil.
Have you checked your coolant level to see if it is dropping?

  • ncampion

Posted March 26, 2008 - 07:26 AM


Agree with Matt4x4. Several oil changes should do it. What little water remains will soon boil off while riding. Do check for blown gaskets as you may have caused increased compression if you sucked water into the intake.

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  • kjr247

Posted March 26, 2008 - 09:25 AM


Matt/NC, I did drain the lines and changed the airfilter and oil filter. I also changed the plug and put a little stabil in the tank. The bike starts ok. I did run it then changed the oil several times. The coolent level has not changed so that is a good thing. I did buy some cheap HD30 oil with no additives to continue to change the oil. I'd hate to waste the HP4 I ussually run.

I am going to change it tonight until the water is gone. Hopefully, it will not smoke when it is all said and done. The bike has only 50 hours on it and was hoping to make her good as new. I will also take off the steering stem and wheels to be sure they are not water logged.

Now I need to work on getting a new brain. Not sure what I was thinking. I should have know when I saw kayakers going down the stream. It was a fun time anyway.

Thanks for the info. I just want to be sure I lessen the damage and determine if there were any Yamaha/WR specific concerns. Appreciate your insight and reply. KJR

  • kjr247

Posted March 26, 2008 - 06:02 PM


It took 5 changes tonight and all is well. Thanks guys.

  • Mark_NZ

Posted March 26, 2008 - 11:28 PM


I had to change mine 5 or 6 times to get it clear as well


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