Here’s how to remove the water pump impeller on a Honda CX500, GL500, CX650, GL650, GL700, GL400 or CX400 motorcycle. This is the same process for the 400, 500 and 650/700 non-turbo variants.
Once you have removed your water pump impeller cover you can see the impeller itself:
The impeller is part number 19215-415-010 for the CX500 and 19215-ME2-000 for the CX/GL650. To see the differences see this page. The impeller is held on by an acorn nut. The acorn nut – 90201-415-000 – is still available new (eBay US and Amazon):
A 10mm socket should get it off:
The threaded rod you see here is the rear end of your camshaft. The copper washer is stuck to the impeller here, too – make sure you locate it, as you don’t want to double up, or not have one at all. It’s part number 90441-706-000 (eBay US or Amazon). Not having one of these (or re-using a crushed one) can result in coolant getting past it, making it’s way down the threads and running out your weep hole.
At this point you can hopefully pull the impeller forward – it slides onto splines on the camshaft so it shouldn’t have any rotational movement available. If you need to apply a prying force to the back of the impeller to help it off be very careful – you don’t want to snap the end of your camshaft. People have reported success using small two jawed pullers or even pressure with pry bars/screwdrivers on either side of the impeller, but again – be careful! Applying force to only one side of a stuck impeller could easily break the end off your camshaft, and that is going to be a headache you don’t want.
Once removed you can see the rear part of the mechanical seal, and in this case the “polo mint” and the thrust washer/spacer still attached to the camshaft.
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