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Discussion Starter · #1 ·
Hey guys, had one member have a little issue, so I wanted to bring it to everyone's attention and make sure all is ok.



When you install the impeller side of the seal (the ceramic 'polo mint' if you will) make sure the impeller is nice and clean. I know when I did mine, I sandblasted the impeller clean, and had no issues.



Anyway, the question is one of the polo wanting to 'pop' back ouf of the impeller, which it really shouldn't do. So yeah, let me know how your seal installs go
 

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Mine did want to pop back out. I finally got everything situated perfectly so it went in straight and didn't want to pop out. But . . . . I still did something wrong because I still have a coolant leak from what looks to be the weep hole. So . . . . I am pulling everything back apart and seeing if I can find my mistake. Install went smoothly tho.



Thanks for putting everything together and making it happen.
 

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Discussion Starter · #3 ·
I remember putting a dab of silicone on the threads of the water pump shaft when I put that nut back on.. something I read on the old forum about a possibility of a leak there?
 

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When fitting the new mech. seal, wipe the polo mint with metho or rubbing alcohol to remove any fingerprints you've put on it installing it into the impellor, then give it a light smear of soap.



Make absolutely certain the metal can is installed dead square.



The copper washer under the dome nut needs to be replaced with a new part or re-annealed by heating cherry red and allowing to cool. A sealant should be used on the cap nut.



Also, sometimes a mech seal will weep for a few hundred miles before it beds in, keep him topped up and cross your fingers that the weep goes away on it's own. If not.....
 

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I am the member with the popping polo Doward mentioned in the first post. I took the chance and put the engine back on the bike. This morning I started the engine for the first time and drove a mile. Unfortunataly the weep hole weeped like never before. I think I lost approx. a bottle of beer of coolant. That's way too much IMHO. I cleaned the impeller first and also used the best joining compound (Hylomar) in both rear cover and impeller to install the seals.



I will now replace the polo in the impeller with a new one (which hopefully doesn't pop back out) to see if that helps. I won't replace the seal in the rear cover since I drove only a mile with it so I hope can take that risk. I will first clean the impeller better than before.



What I also noticed during installation, is that the sealpart that goes into the rear cover (i.e. the metal part with the spring etc.) is about 3mm lower than the previous (Wemoto) seal. I hope that doesn't lead to a less firm joint between the sealparts once installed.
 

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Replaced the mechanical seal on my '81 GL500i using the "Sheps" method. Process went very smoothly and there has been no weeping. Smeared a little Dawn on the mating surfaces before installing the impeller. Made sure the 'polo mint' recess machined into the back of the impeller was free of all old seal material. I did not use any adhesive here. It is an interferrence fit and with the seal spring pressure it shouldn't move. Do NOT allow any solvents (WD40, carb cleaners, etc) to contaminate the rubber cup that holds the 'polo mint'. That can cause swelling and make it impossible for those parts to fit properly in the impeller recess. I disagree somewhat with a previous poster that there is a 'bedding in' period here. If the correct parts are properly installed, there should be NO leaks until the thing wears out again. Also, a previous poster (JiMi) reported a 3mm difference in the height of the seal assembly with the new part being shorter. That sounds like a real problem that needs to be explored.
 

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Here's a positive (
) update of my situation:



Today I replaced the polo for a new one. But not after I thoroughly cleaned the impeller with a Dremel. The new polo also wanted to pop back out just like the first one, but not that fast (about 60 sec). I used a new copper washer and tightened the endnut a bit more firmly than the first time, but not too (because it could damage the shaft!!!) Once I reinstalled everything I drove about 2 or 3 miles to get the engine warmed up. And not a single drop of coolant came out of the weephole. So everything is looking good so far.

I have the feeling that I am to blame for the leaking problem for not tightening the endnut firmly enough. Not the seals.
 

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"Posted 22 March 2011 - 01:39 PM



The ceramic,"Polo Mint" sits inside it's own rubber cup and that goes into the impeller.It has a chamfered edge and a flat edge(Not easily see-able) and the flat edge goes into the rubber cup." Shep.



Thought I'd add the above quote here. Maybe the position of the Polo Mint in the rubber cup has something to do with the popping out?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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When I replaced my seal using Shep's in-frame method, I had trouble getting the polo mint from the Yamaha kit to go INTO the impeller. I'm not certain, but I think I reused the old Honda rubber seat in order to get it to fit correctly.



In retrospect, I decided that a dab of plumbers grease would have made it easier, but in light of the current conversation, I wonder if it would have stayed.





R
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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D'oh! Double post.



R
 
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