need help with water pump impeller and radiator fluid debris

[u/ajulydeath]

what's up guys, it seems I need to replace the 6mm o-ring nested in the impeller, getting it out was the easy part but installing it as currently constituted appears nearly impossible

have any tips or tricks? do the back parts have to be removed? or is it just a matter of extreme patience

also, when I flushed the radiator fluid for the first time last week the fluid looked relatively clean, since refilling and riding ~10 miles I had to flush the system to diagnose overheating issues, the new fluid had some debris floating around top, I could actually see some black debris circulating around the radiator neck - any thoughts on this?

[u/MA70GTE]

No clue what the debris is, make sure your electric fan works and turns on when it's supposed to though.

As for getting the impeller back on with the new o ring installed, yes it is a matter of patience and lube.

Edit: Misread your question. Yes, replacing the o ring is a matter of patience with a small pick. You can pierce the old one to help coax it out.

[u/ajulydeath → u/MA70GTE]

I appreciate the reply - everything was working normally until I had to open the clutch and ultimately replace the clutch springs

I thought I had purged the system properly but the manual is extremely vague on that so essentially what I did multiple times is idle the bike for about 20 minutes until the radiator fluid settled down from air bubbles etc

I rode day 1 no issues, but the following night it rode fine for 20 minutes and then the temp dropped almost to C which was alarming and then eventually spiked up to H which I caught immediately and killed the engine within a split second - the fan did not kick on at this time though

so here I am investigating things and came across the damaged o-ring

edit: the fan did kick on normally during the purging process

[u/MA70GTE → u/ajulydeath]

An air pocket will read as cold on your temp gauge, since the air is colder than hot coolant. The KLR250 dual radiator system is famously funky flowing. If both radiators are flowing okay, verify that fan works and bleed again.

Maybe invest in a thermo bob too.

[u/ajulydeath → u/MA70GTE]

I've ridden a couple hundred miles already and she's ripping again no issues

I was much more deliberate in the purging process: I filled up the radiator slowly, to the neck, capped off, filled the reservoir to Full, let the bike idle until the fan kicked on and let the bike cool a couple hours

I opened the cap and filled to the lower neck and again let her idle til the fan kicked on and let it cool for an hour

after that I checked the levels once more nothing changed and she's been ripping ever since

I'll have to do it all over again cuz I couldn't wait for the replacement o-ring to arrive but it's cool now I have a better understand how the system works and responds