Here is how to remove the water pump (or impeller) cover on a Honda CX400, CX500, CX650, GL400, GL500, GL650 or GL700 motorcycle. The 400/500 and 650 covers are different in shape and depth over where the impeller sits but the bolts and procedures are the same.
There’s a few reasons you might want to do this; an in-bike mechanical seal replacement, just to check the impeller or removing the rear cover are a few. The impeller cover is at the rear top part of the engine and looks like this:
The hose at the top leads to the thermostat housing and can be removed by loosening the clamp and then lifting it upwards:
Now that that’s removed there are five bolts holding the impeller cover on:
The three smaller bolts circled with the thinner line are identical and have 8mm heads (6x25mm bolts, part number 96001-0602500 or 96000-0602500):
The two bolts circled with the thicker line are identical and have a 12mm head (8x65mm bolts, part number 95700-0806500 or 95701-0806500):
Now that the bolts are out, you should be looking at this:
There are two dowels between the rear engine cover and impeller cover so you won’t be able to twist it off – and the cover is often stuck on quite firmly. Tapping with a rubber mallet might help, but we have had good luck carefully using a disposable cutting blade (or razorblade) tapped gently inbetween the impeller cover and rear cover – just avoid the dowels, which are located around the bolt holes for the larger (12mm head) bolts. Once you have tapped the razorblade in and broken the seal in a couple of places you should be able to pull the impeller cover off towards the rear of the motor, and you’ll probably get a bit of coolant running out:
Cover removed – you can see the dowels still in place:
If you came here from the triple bypass page, click here to go back. Or read on for how to remove the water pump impeller itself.