Where to look first,

I currently have a 98 WR400 lump on my bench, all i know is that it had water problems that were fixed then the oil turned milky, im not too sure how much riding was done but it was only a few days.

So wheres the oil leaking.. can anyone give me tips on how to find out,

My limited experience tells me wither water pump or head gasket (engine maybe ran dry)

Or is there somewhere else i should be looking?



normally, milky oil means coolant leaking in from the water pump seals. i don't know the wr400 very well, but it's a very common problem on the wr450.

Stripped out the waterpump and the head, new gaskets and seals tomorrow!

this is the first time iv done a 4 stroke and it wasnt as scary as i expected, especially with all the hints and tips on here :thumbsup::ride:

There not actually "that" complex once you get down and dirty!

I think the hardest part is getting the cams back in exactly right was a pain got it one tooth off the first time.

iv marked accross the chain with a marker, just hope it holds. I couldnt see any real damage on the headgasket or seals,

would it be just to replace and rebuild or do i need to get head skimmed

(im 75% sure the leak was the water pump due to the sheer volume of water in the oil)

Also, On my 98, theres no expansion chamber.... so where does the water go when it expands? could this have been what blew the seals?

The water goes out the overflow tube onto the ground...

Make sure the overflow tube isn't plugged and don't plug it on reassembly by zip tying it to the frame, which pinched it closed, like a friend of mine did. :thumbsup: WR Dave.

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