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Hello after the mass over heating problem ive noticed milky oil again. I take it that the head gasket and water pump are the only ways water can get i the oil? I replaced the head gasket 6 months ago but due to the over heating it may have gone again. But i think the pump is knacked here because warm water isnt getting past the thermostat and circulating around the system. This is also not turning on the fan which I think is caused by the thermo-fan switch not getting heated

Any ideas as I'd hate to have to pay£175 for new pump

or is the thermostat stuck in the closed position, try taking it out and see what happens. As for the HG, you could try compression testing first, but if its only gone between oil and water jacket this isn't conclusive.

You shouldn't get water into the oil via the pump, there is a drain hole at the bottom of the pump which diverts the coolant if the seals are shagged and you will see a pool of water forming under the bike. If you do have coolant in the oil it is almost certainly a HG issue.

Now, if you do have a coolant pump issue (which could be causing your HGs to go through overheating) before spending £175 PM Mori Man as you may be surprised at the saving direct from Japan. Still not cheap, but cheaper. Or you could try this http://cgi.ebay.co.uk/Kawasaki-ZXR400-H ... 5196fa78fd Although this is for a H, according to the microfiches it's the same part on the L and it looks the same to me.

Pulled the water pump out, good news is the seals are ok bad news is the oil looks like coffee. Definatly the HG. Not entirely sure why this has blown as I replaced it 6 months ago.

Poss when the thermostat stuck it over-heated the head???

Might explain why the bike would run for 5 mins then cut out and struggle to start till it cooled down

Could be a warped head? Or a hairline crack?

Agree with Rob. If you've had an overheating issue previously which blew the HG you might need the head skimming if it is warped - or if it's really bad it might be toast

Get your cylinder head skimmed - will benefit from it wether needed or not.

Test your thermo switch is operating - thought mine was until I saw the fan blades had melted

In all honesty most of these bikes are coming upto being 20+yrs old so a new thermo switch & thermostat isn't much to ask, done both on my bike

Pretty sure the thermo switch is half price here so PM if you go that route.

Low mileage is not an indication of good condition - unless the bike is only a few years old , time gets us all !

MM!

Replaced the HG last time due to low compression which turned out to be piston rings being worn. Shall have it skimmed since I need to change and see about getting it checked for hair line-cracks

Yeh I've ordered a new thermostat and the thermo switch checked out ok. Just replace and go from here