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Discussion Starter #1
02 ST4S. First decent ride of the season and I find mayo in the sight glasses on both sides when I get back.Too hot and long a ride to still be winter condensation.
Drained the water and oil...no oil in the coolant which has got to be a plus.
Pulled the alternator side cover off and found heaps of mayo around the water pump and inside the cover.
One of the pump's ball races is rough so I'll replace both of them.
What do I need to replace as far as the seals? do I need to buy a whole new impeller with the spring part of the seals attached or can I just do the rubber and ceramic bits?
Thanks.
 

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Colin,

Recently, I had a leaking waterpump seal on my ST3s 2007 with similar symptoms. I had the following parts replaced (see Ducati ST4s 2002 parts manual, pages 55-57):

#9: 702.5.010.1A bearing
#11: 702.4.009.1A bearing
#26: 930.5.005.1A seal
#28: 930.5.006.2B mechanical seal

The problem is gone now (I used to lose about half a liter of coolant through the seal in ~1500km). These parts appear to be identical in my ST3 and your ST4. You may find some more mayo after the repair and your oil change. These are remains of coolant that are still in the system. A second oil change will solve that.

Good luck,
Mark
 

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Discussion Starter #3
Thanks Mark....that was the same symptoms for me.Slight water loss from the header tank over 1000km...thought it could have been an air bubble but then it was a little bit more .....and then the mayo signs in the sight glass yesterday.
Good news compared to other possibilities.
 

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They are not hard to replace, however do make a note of how it goes together as I found the diagrams incorrect for st4s. I bought the bearings from elsewhere as they were a lot cheaper. One word of advice if you do it yourself! Make sure you heat the bolts that hold the bearings in as they are have thread lock on them...

John
 

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Discussion Starter #5
Thanks John...hope I remember how it goes back together by the time the bits get here.
Found the mechanical seal but no one in australasia seems to have the other and say 3 or 4 weeks from Italy for it to get here.
I'm guessing I'll find the bearings with a generic bearing supplier.
Any recommendations for quick supplier of the seal?
 

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Sorry, no idea on the seal? I dont remember having any problems from the local Ducati dealer. I can make some enquiries if you wish?

John
 

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Colin, good luck on the seal replacement! If you would not mind, would you consider photo documentation and posting? Especially if as posts state the ST4s manual is incorrect, a few key photos when you do replace may be quite helpful to other members should something similar develop. Again, best of luck and happy spring to you down under.

Vince
 
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