Ex-500.com - The home of the Kawasaki EX500 / Ninja 500R banner
1 - 3 of 3 Posts

2000 Ex-500
29 Posts
Discussion Starter · #1 ·

First, I did a search of the forum and found LOTS of posts about coolant IN OIL, but only a few about oil IN COOLANT. If this issue I have described has been addressed, please accept my apologies, and I humbly accept a flaming and possibly a link to my answer.

I have a 2000 EX-500 with 13000 miles, and I am the original owner (OK..everybody at once...GARAGE QUEEN!!!)

I am doing winter maintenance and as part of that, I decided to do a proactive changing of the 20 year old major cooling hoses before they made the decision for me.

When I flushed the system I had what looked like a thin skim layer of oil on top the cooling fluid in the receptacle I used to collect it. Much less than 1mm, but you could see the colorful gas/oil like sheen. This was after a drain and 2 flushes until i got straight water.

After a brief freak out about my head gasket being shot, I checked my compression and it was beautiful 173-ish and 178-ish.

I also checked my oil and saw no evidence of coolant in the oil. Nothing "milky"

I did clean the two cooling pipes that stick into the head next to the spark plugs, and changed the O rings. The pipes were a little gunky, and the O Rings were in tact and still had some life left in them.

I did my last flush about 3 years ago and did not notice anything unusual, but I don't remember if I looked too hard, and I did change the O Rings at that time.

Although I have no leaks of coolant or oil coming from the vicinity of the water pump (or anywhere else), I am leaning towards the water pump gaskets that have been mentioned several times here.

What do you think and / or what else might it be?


As an aside you guys are great in this forum. I went from ZERO motorcycle maintenance experience to delving into really complicated stuff all based on this forum, not to mention some really cool modifications. All thanks to this forum. I am also a dreaded Prius owner, and those forums are a complete mess compared to this one. So...thanks for everything.

2004 Kawasaki Ninja 500
43 Posts
This response isn't coming from a place of deep experience or knowledge of this motorcycle - so take this with a grain of salt. But I have wrenched on vehicles for most of my life, I've raced little Formula Vees, and I did stay at a Holiday Inn Express lastnight...

But I would think a very thin skim layer or some residue floating on top of the drained coolant wouldn't be something to worry about. At least not yet.

When is the last time the bike got to stretch her legs? And you say it's possible that the last coolant drain had the same thing, but you're not 100% sure?
You could always do a cheap fill, run, and drain again to see if it persists. Especially after a flush, you'd know for sure if there's actually a leak somewhere.
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.