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Hi all. New to this forum and hoping to get some help with a problem I am having. Just acquired a 1983 GL650I with a coolant in base issue. I tracked the problem to the water pump impeller loose on the camshaft. Splines are stripped on the impeller but cam looks OK. This part is obsolete so cannot be bought from Honda. I have been researching various sources for a replacement with no luck as yet. The parts manual shows a different part no. (19215-ME2-000) for the 650 than that of the 500 (19215-415-010). Can anyone tell me what is the difference between the two and can the cx/gl 500 impeller be used in the 650? Thank you in advance for your input. Daryl
 

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Hi all. New to this forum and hoping to get some help with a problem I am having. Just acquired a 1983 GL650I with a coolant in base issue. I tracked the problem to the water pump impeller loose on the camshaft. Splines are stripped on the impeller but cam looks OK. This part is obsolete so cannot be bought from Honda. I have been researching various sources for a replacement with no luck as yet. The parts manual shows a different part no. (19215-ME2-000) for the 650 than that of the 500 (19215-415-010). Can anyone tell me what is the difference between the two and can the cx/gl 500 impeller be used in the 650? Thank you in advance for your input. Daryl
Look at this:
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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The 500 and 650 impellers are not interchangeable. Nor are the pump covers.
 

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Don't forget a new copper crush washer and the washer behind the impeller.
 

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Beware Doug. You are right, if you say "a new sealing washer" but NO COPPER WASHER in combination with my impeller!!!



...The reproduced water pump impellers are made of high-quality aluminum alloy and hard-anodized to protect against corosion and cavitation damage.

The manufacturing quality and material quality of these impellers is significantly better than the original cast iron part.

But: The use of the original copper sealing washer is not permitted and can lead to material damage, because aluminium, copper and water is no allowed combination.


That's why the impeller will be delivered together with a special turned aluminium washer and a detailed information on installing.
And only this washer is allowed to use!


...And you're right, and this is a very important notice, not to forget the support ring on the camshaft-end under the impeller:


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Sometimes this ring gets lost because it's stuck in the old seal, or it's so rusted that you can't even see it


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It is also important that the sliding surface on which the shaft seal runs is clean and smooth.

The picture is showing a camshaft from a CX 500 Turbo that has been restored. Here we used a circular grinding mashine,
but I don't have that option anymore.

Of course, you can also grind the sliding surface with fine abrasive cloth.

You don't have to remove the camshaft for this. But you can work better if the Boss, Cam Sprocket is removed.



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Good to know! I didn't realize there was a difference with the aftermarket unit. (y)
 
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No problem, Doug, that's why you'll receive precise instructions with the relevant information together with the impeller.

But the point about the disc/support ring was certainly not unimportant for Dary, because we don't know yet how much experience he has with the CX engine ;) .



...Another thing I recommend related to assembly is to replace the bottom bolt of the water pump cover with a stud and nut.

The screw tends to rot over time and can tear off. The rest is then very difficult to remove.

If you're lucky, you can turn it out with a welded washer.

If not, only milling out helps.


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'84 CX650E that is evolving into a GL500
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To clarify about the covers and impellers, the part of the camshaft that the impeller fits on is identical for all CX/GL500/650 engines. Unless I am mistaken any 500 or 650 water pump cover will bolt up to any CX/GL500/GL650 engine BUT the 650 impeller is taller and the cover is made to fit over it so while you could in a pinch run a 500 impeller in a 650 cover you couldn't use a 650 impeller in a 500 cover.
FWIW, I used a 500 impeller in a 650 with a 650 cover for a few years on my winter machine and it was fine but I wouldn't recommend it in hot weather.

What do you mean by "coolant in base issue"? If you mean coolant getting into the crankcase, a leak from the water pump mechanical seal (either a failed seal or a loose impeller) shouldn't cause coolant to get into the crankcase unless the weep hole is blocked. These links explain how it works and what to look for

Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 

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...while you could in a pinch run a 500 impeller in a 650 cover ...
Sorry Bob, but if you do that, then you can also leave out the impeller altogether.


We're talking about a "pump" here and not about a stirring device that is used to froth milk in a coffee.


There is only a few 10ths of a mm of air between the impeller and the housing cover.

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The 500 impeller is 5 mm then the 650. So you have no more pumping effect, but only turbulence.

These turbulences creates cavitation damage (Please have a click to the link and look the video)


The fact that this worked in your winter combination is due on the one hand to the low temperatures and on the other hand to the fact that the CX engine is a thermally very healthy and insensitive engine. But over time your impeller will be destroyed.

So, if you don't have a 650 impeller and want to mount a 500 in an emergency, then you must also mount the 500 cover.
 

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'84 CX650E that is evolving into a GL500
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If I had the choice I would have but I didn't. I didn't say running a 500 impeller in a 650 was ideal, just that it would fit and worked for me.
In fact, it must have been pumping a lot better than you think it would because the water pipe did heat up just about as fast as I would expect it to.
And when I had the engine apart several times (transmission problems I never did solve) there was no sign of abnormal wear to either the impeller or the cover.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Honda used aluminum crush washers in the forks, for the same galvanic concerns, I suspect. That would be a viable alternate if, down the road, you need to replace the one supplied with the impeller.
 

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Honda used aluminum crush washers in the forks, ...

These washers are thinner and have a smaller diameter. The washers for the impellers are no standard-parts, not even the copper ones.

...For overseas deliveries or generally for deliveries abroad I also can add a second washer to save shipping costs in case of use one. ;)


In an emergency it is possible to use the washers a second time, if you put an O-ring 6x1,5 on the shaft below the washer.

The copper ones you can use a second time, if you soft-anneal it. To be on the safe side, you should also put an o-ring underneath it.
 
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