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Discussion Starter · #1 ·
as the title says...noticed a slight leak under my water pump when I did my end of season oil change in November. I thought I traced it to the pump cover gasket so ordered new gasket and 2 O rings for the metal water pipes. Spent 4 hours today removing the fairings and drained coolant, pulled gasket cover, replaced gasket and O rings, re filled with coolant. Placed a white paper towel under the water pump to check for leaks and I'll be damned if I didn't see 4 or 5 drops on it after running the bike for about 10 minutes.

Even though I wished really, really hard that it was just leftover coolant from the change that somehow dripped out...I don't think so. It seemed to be coming from where the water pump connects to the motor. I think the only other items to replace are the mechanical water seal and the O ring (and I keep hearing @SparkyMJ saying recently that as long as you're in there you might as well replace everything).

So now I'm thinking if I do this I probably need to order another new water pump gasket and O rings plus mechanical seal and o ring..crap...or I just take tit to the dealer since I need a new chain, sprockets and tires, anyway. (hate to think how many weeks THAT will take to get done...).

Attached pic shows bottom of water pump. Yellow line is where pump cover meets water pump and where I replaced the gasket. Circled area in red is where the coolant appeared to be dripping from. Am I correct in thinking it's likely the mechanical seal? (no coolant in my engine oil..just leaking out)

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Yes, you are correct, and thanks for the shoutout! That area will leak when the "weep hole" on the water pump is leaking. And depending on what fluid is coming out of there, you can expect what to replace inside. This is actually specified in the shop manual for the bike! That is the good news.

Here's the bad news. I was going to rebuild my water pump just like you. And I even ordered all the parts, but later found out that there is a seal that you cannot buy alone, that you need to replace when doing a water pump rebuild. It is terrible. I literally ended up returning all the water pump parts, and buying a whole new water pump, which comes pre assembled, lubed, sealed, and has all the parts obviously.

The pump IIRC was about $250 shipped, and the install is easy. If you just used those O rings to install the pipes to the pump, I think they are fine to reuse. Clean them off, clean the hard lines they connect to, and of course the new pump will be spotless. Apply a smidge of silicone grease to the O rings as well to ensure sealing, and easy assembly.

So if you are willing to foot the bill of $250, and eat the cost of the parts you already bought, it is a very easy repair. That, and the lesson I've learned in the past is to test the cooling system with distilled water maybe with a tiny bit of actual coolant. So that you don't waste precious new coolant! After it runs and the radiator fan comes on and I ride around for like one day like that do I drain it all and put real coolant back in. Safer if it leaks, cheaper if you waste it, and less hazardous. Plus, then you get a quick flush of the newly sealed system prior to putting the coolant in it to stay for a long time.

That said, new chain and sprockets isn't an awful job, you could do it while the dealer is mounting your new shoes though. Up to you! We are here to help if you want to take on those jobs and save some cash and/or time. Hope this helps.

-Mike
 

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Discussion Starter · #3 ·
SparkyMJ....Distilled water, brilliant!! Man, that makes so much sense. Well, it looks like I'll be doing a water pump, too. It's interesting, this bike hasn't really cost me anything other than a set of tires and some brake pads (plus all the fluids and filters..and driving lights, led bulbs, windscreens...) over the past 5 1/2 years...then all of a sudden everything hits at once - tires, chain/sprockets, water pump...kind of like an older car where everything needs to be replaced at once.

I think I'll still let the dealer do the chain and sprockets (have read too many stories of the challenge of getting off the front sprocket nut) when I'm in there for tires. I know they are always backed up in the service dept at this time of year.

It looks like the water pump comes off with 2 bolts? Manual says impeller needs to come off, too, is that correct? Looks like a relatively easy job to replace. It also looks like I should have looked at the manual, first, then I would have seen where the weep hole was and not wasted my time on a cover gasket replacement. Live and learn. Thanks for the help.
 

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I believe it is two bolts off the top of my head. And like I mentioned, if you have the main huge O-ring that is inside the engine crankcase half that seals the water pump in, put that new one in.

The manual never ceases to shock me with how much info it actually has in it, lol. Sometimes I just don't know what to look for to answer my question, so I come here. Hope this helps! Take your sweet time putting the pump in, clean every single surface and part prior to installation, and follow the manual verbatim. You should be in perfect shape. I am about to do the install on mine this week, I will update here if I find any hiccups in the process to save you the hassle.

-Mike
 

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Discussion Starter · #5 ·
I believe it is two bolts off the top of my head. And like I mentioned, if you have the main huge O-ring that is inside the engine crankcase half that seals the water pump in, put that new one in.

The manual never ceases to shock me with how much info it actually has in it, lol. Sometimes I just don't know what to look for to answer my question, so I come here. Hope this helps! Take your sweet time putting the pump in, clean every single surface and part prior to installation, and follow the manual verbatim. You should be in perfect shape. I am about to do the install on mine this week, I will update here if I find any hiccups in the process to save you the hassle.

-Mike
Be sure to update on the process! As you said, the manual makes it look as easy as draining coolant, removing pipes and 2 bolts to pull the water pump out. New o ring, line up the shaft, and reassemble. I see it's $226 on Revzilla with free shipping. Another Kawi site had it at about $246.
 

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Tech tip, be sure to put a very light coat of grease on O-rings when installing them.
 
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Discussion Starter · #7 ·
Tech tip, be sure to put a very light coat of grease on O-rings when installing them.
thanks, that's a great tip. I did grease my o rings on the metal pipes when I installed them. Removing the metal pipes took a lot of force as the old o rings were dry which made the pipes want to stay attached to the pump cover. Greasing the new ones made the re-install a breeze.
 

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Keep a few of this coolant O-rings on hand, just in case, trust me on that.
 

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Keep a few of this coolant O-rings on hand, just in case, trust me on that.
True that. I have a bag of the repeatedly used ones now lol. My pump main O rings show up tomorrow, and I'll be putting the pump in. Then hopefully getting my remaining coolant pipes back from a shop on Wed or Thurs, and finally going riding! Hopefully no surprises come up...

-Mike
 

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Discussion Starter · #10 ·
SparkyMJ - forgot to mention that when I took apart my water pump cover and pulled the hard pipes I noticed the inside of them were kind of bumpy and…greasy..? Kind of like a coating that I could have scraped off with my fingernail. Weird. My coolant gets changed yearly so that wouldn’t be the issue…but I still found it odd.
 

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DUDE. I had this problem as well. Was it black? If so, it is the paint they apply at the factory to seal the steel. It seems to naturally flake off and just be terrible. I was so concerned that I made a thread about it, go check it out. I think I titled it something about rust in hard coolant lines, you can just find it by seeing my posts off my profile. I ended up getting those hard lines treated and powder coated. Check out that thread! I get the pipes back in a day or so, and then it'll be going back together!

-Mike
 

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Discussion Starter · #12 ·
Yeah, I remember the thread..that’s why I took a looked in mine! I should have taken a picture. Mine almost felt bumpy and textured, kind of had the look of really grainy leather. I’ll look again when I get the pipes off for the water pump replacement. Mine was still all black, nothing had flaked off…more like something had built up in the pipes.
 

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So I installed my new water pump, new O ring, cleaned and powder coated coolant lines, and fresh O rings on those. It came out perfect, and the install was super easy. Just put the new O rings on the parts, applied some grease or engine oil where needed, and slowly wiggled and tightened down the parts. I was confident my system wouldn't leak, so I put straight coolant in. Sure enough, no leaks, and tonight after riding it a few times, I will top off the radiator once it cools down. I did have to add a bunch of oil, since it poured out when I removed the pump, so be careful. It may not pour out as much if you have the bike on a rear stand unlike me.

All in all, about $250 for the pump shipped, a couple bucks in O rings, powder on my coolant pipes running to the pump, and a 45 minute install. Worth every penny, and it runs great!

-Mike
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84' Goldwing Aspencade, 91' EX500, 98' Ninja 250 w/ 17' 300 engine, 07 EX500
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So I installed my new water pump, new O ring, cleaned and powder coated coolant lines, and fresh O rings on those. It came out perfect, and the install was super easy. Just put the new O rings on the parts, applied some grease or engine oil where needed, and slowly wiggled and tightened down the parts. I was confident my system wouldn't leak, so I put straight coolant in. Sure enough, no leaks, and tonight after riding it a few times, I will top off the radiator once it cools down. I did have to add a bunch of oil, since it poured out when I removed the pump, so be careful. It may not pour out as much if you have the bike on a rear stand unlike me.

All in all, about $250 for the pump shipped, a couple bucks in O rings, powder on my coolant pipes running to the pump, and a 45 minute install. Worth every penny, and it runs great!

-Mike View attachment 115978
View attachment 115979
Looks awesome, love the red. I have a question, did you also do the coolant pipe for the head?

Also, also how much did powder coating cost?
 

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I actually did not do the top pipe. I was in a rush, and I actually have a BNIB top hard pipe too. DOH! But I think it's not a big deal, since it isn't really visible anyhow.

If you are interested in some powder work, reach out to @jkv45 about it. He commented on the original post I made about having rust on these pipes a while back.

All in all though, really happy with the fresh parts and the new water pump. Guess under normal ish circumstances, expect a N300 water pump to go about 50,000 miles. I probably change my coolant more often than needed, but helps.

Bike is basically ready to crush it at the track now. Some last minute tune ups here and there and a good cleaning, and I think it'll be ready to rip!

-Mike
 
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