Monday, August 22, 2005

Water Pump leaking

**Please note: MV has recently changed the water pump seals in question so we don't expect future issues. Please report if your 2006 production bike (or later) develops a leak. Email me at right or post a comment below.

There are two main causes of seeing blue (factory) coolant on the lower cowl. One of the first telltale signs:


1) Normal coolant overflow from the overflow drain as seen here highlighted in red (ignore the rest for now):

The main cause of simple overflow is a reservoir overfilled. Keeping your reservoir at the MIN line (found below instrument cluster/clocks) is the usual prevention of this type of "leaking". Many owners also shut down their bike's engine but keep the ignition turned to on to allow the fans to run, thus cooling the radiators even after the ride. The normal turning off point is flexible but is often 185F /85C.

2) The second type of leaking is from the Water Pump itself, two internal parts in particular.

**NOTE: For 2006+ bikes or to retrofit the new pieces to your 2000-2005 bike please see section 3)

For 2000-2005 See numbers 10 & 23 below; per Factory Parts Manual section G07.
Click to enlarge:

The part numbers for the two points of failure (#10 & #23 above) are:

#10 800081236
#23 800081237

One contributor suggested preventative replacement O-ring while Water Pump is apart (#14 above) - though no others (+25) have required this part for successful fix:

#14 800086702

In ONE case a bike also required the shaft be replaced due to scoring, check your part for any abnormal scoring and replace if required. Part number is:

#9 800081539

2006+ bikes or to retrofit new design:

The factory have changed the water pump makeup to diverge from the previous design. They have moved from a shaft and two seals to a shaft and one seal as below (click to enlarge). See parts numbered 7 and 19:

The part numbers for the new design are as follows:
#7 8000A6709
#19 8000A6708

The following photo shows the hole out of which the coolant escapes, see red arrow.


If you see this much coolant accumulated you may very well have a water pump leak. Now, what to do? Some owners, author included, have had the leak subside after 500-1000miles/800-1600km. If leak does not subside on it's own then replacement of the above two parts are known to resolve the very vast majority of leaks. Often, if under warranty, the factory will replace the entire unit rather than the two parts in question. This varies by geography.



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