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Thread: Water Pump Seals

  1. #1
    apriliaforum expert kzmille's Avatar
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    Water Pump Seals

    Water Pump Seal
    ------------------------------------------------------------------------
    Since the introduction of the V60 Rotax engine there have been many instances of water pump seal replacement that fail. The procedures outlined in the factory shop manual for both disassembly and assembly are not very dependable! It looks quite simple. Once everything is torn down you drive the water pump shaft out of the cover with a soft hammer against the threaded end. Now use a pin punch to drive the water and oil seals out of the primary cover. This action moves the oil seal first, very easily, till it comes up against the water seal (called the sliding ring in the parts book). It then requires significantly more force to get the water seal moving. On my first attempt at this job, by the time I got the seals out, the oil seal had been so distorted that it made a deep gouge in the housing bore wrecking the primary cover. I now use an expanding bearing remover with slide hammer to remove the water seal from the outside first and then remove the oil seal.

    The manual then directs you to drive in the oil seal followed by the water seal with the Aprilia special tools. Sounds good. Now you are told to drive the water pump shaft through the water seal, oil seal, and housing bore with a hammer and block of wood. This directive is so illconceived that it is laughable. For those who do not know, the water seal is actually a ceramic seal common to virtually all water pumps. It is made up of two dissimilar ceramic rings, very finely finished, one fixed, one rotating which are held in contact by a spring. A rubber boot surrounds the spring to make the package water tight. These ceramic rings are fragile. While driving the shaft through the seal the force of each blow must travel through a rubber seal to the 1st ring, to the 2nd ring, through the rubber boot, through the spring after it bottoms,and through the rubber boot again before the shaft moves through its interference fit in the seal. The chances of doing this without cracking the rings are not good. Then the shaft must find its way, unguided, through the oil seal. While tearing one down once I found that the spring in the oil seal was half way out of its groove. Witness marks indicate that it was jarred out of place when the shaft was driven through upon initial assembly at the factory. Lastly the shaft must now find its way into the bearing bore in the housing with only a few thousandths clearance while you're pounding away on your block of wood.

    There is a better way. It does require some special tools made on the lathe but they are simple and I will describe them and the procedure. First install the oil seal in the housing. A light smear of oil on seal OD and housing bore helps ease it in without damage. Set the housing aside for later. Now we need to press the shaft, threaded end first, through the back side of the water seal. This requires making special tools. A thick steel plate with a 23/64th inch hole drilled through it makes our anvil. This must be drilled on the drill press, milling machine or lathe so it is perpendicular. Now make a guide pin from steel turned on the lathe to a slip fit in the drilled hole. Thread one end of the pin internally 8mx1.25 while on the lathe. Do your threads first! Then turn the OD. Make the pin about 1 1/2 inch long.

    Before proceeding, check the edges of the hole that goes through the pump shaft. If there are sharp edges or burrs they will cut the lip of the oil seal when the shaft is installed. I use a small grinding point followed by fine wet/dry sand paper to smooth the edges. Screw the pin onto the pump shaft. Make sure it's straight. Insert the guide pin and pump shaft, guide pin first, through the back side of the seal. Invert everything and insert the guide pin into the hole in the anvil. Carefully press the shaft into the seal. Make sure the face at the base of the threads on the pump shaft is flush with the flange of the seal. Now apply some moly assembly lube to the pump shaft bearing bore, some light grease or oil on the oil seal and shaft, and insert the pump shaft through the oil seal and housing bore. Now the lathe comes in again to make a drift to bear against the flange at the OD of the water seal and press it in till it bottoms against the flange. I made mine from aluminum and drilled it to receive the guide pin so everything is kept nice and square while pressing in. Remove the guide pin and install the impeller. Do not use thread locking compounds. Install the washer, drive pin and plastic gear on the back side and you're ready to put it all back together confident that you haven't damaged anything because of a bunch of hammering.

    The tools from left to right: Anvil, Guide Pin, Drift for Water Seal, Mandrel for Drift. The drift could be made in one piece. Notice that the drift and mandrel are drilled to receive the guide pin so it can be left in place on the shaft while pressing in the seal. This helps to insure perfect alignment during the pressing operation.
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    Last edited by kzmille; 02-07-2012 at 02:40 PM.

  2. #2
    %@*#&! hank's Avatar
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    Thank you for that OUTSTANDING write-up.

    I have had the weep hole gasket replaced 3 times and it now leaks more than ever..... Where I thought the design simply sucked or perhaps the gasket was faulty, or even the mechanic missed something, it is evident that the Aprilia-supplied instructions suck....

    I will print out your write-up and hand it to the mechanic next time I get this looked at.

    Thanks again.

  3. #3
    apriliaforum expert kzmille's Avatar
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    Removing and installing the water seal (sliding ring)

    What follows are the critical operations using the procedures and tools I developed. Refer to the article above for the full sequence and a description of the tools.


    I use this pilot bearing puller to remove the water seal. This prevents damage to the housing which sometimes occurs when driving the seals out with a punch as directed in the manual.
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    Last edited by kzmille; 04-07-2005 at 12:07 AM.

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    apriliaforum expert kzmille's Avatar
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    Guide pin installed on the water pump shaft.
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    apriliaforum expert kzmille's Avatar
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    Insert the assembly through the back side of the seal.
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    apriliaforum expert kzmille's Avatar
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    In this shot you can see how the drift is machined to contact the outer rim of the seal.
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    apriliaforum expert kzmille's Avatar
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    Before proceeding, check the edges of the hole that goes through the pump shaft. If there are sharp edges or burrs they will cut the lip of the oil seal when the shaft is installed. I use a small grinding point followed by a mounted rubber abrasive point to smooth and polish around the hole edges. Insert the guide pin, shaft and seal into the anvil.
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    Last edited by kzmille; 12-31-2011 at 12:43 AM.

  8. #8
    apriliaforum expert kzmille's Avatar
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    Carefully press the shaft in till the face of the shaft contacts the anvil.
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    apriliaforum expert kzmille's Avatar
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    After you have installed the oil seal lubricate the shaft bearing bore and the oil seal lip and insert the shaft through the seal and housing.
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    apriliaforum expert kzmille's Avatar
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    Pressing the seal home.
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  11. #11
    apriliaforum expert kzmille's Avatar
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    All pressed in.
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    apriliaforum expert kzmille's Avatar
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    Remove the guide pin and you are ready to install the impeller and drive components and put it all back together confident that the job is done correctly.
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    apriliaforum expert Futura's Avatar
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    Thanks for the very detailed procedure. You seem very much like me in your approach to things. I too have fabricated many special tools to do jobs properly.

    I have a new Futura and have had no problem with the WP yet. Is the failure only due to poor factory assembly, or is it a lubrication failure? Is there anything you think might be done preventatively, such as WP lube additive?

  14. #14
    apriliaforum expert kzmille's Avatar
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    There was an oil seal upgrade sometime during or after the 2001 model year. The original seal was black. The upgraded seal is dark brown. This is the only change I am aware of. I just think it is a bad procedure, not to be confused with poor workmanship which I do not think is the problem. There are two possible problems; leaking either oil or water from the weep hole. The oil leak problem was partially corrected with the upgraded oil seal. Lubrication is not an issue with either seal provided the oil seal and pump shaft are lubed during assembly. Water pump lube additive is not necessary. Water pump seals(the water seal) last almost for ever. If they are damaged during assembly they usually leak immediately. The oil seal can work well for a long time even if compromised and the leak is very small. There is no oil pressure near the seal. The pump shaft, oil seal and drive gear are lubricated by oil splash. Inspect the weep hole when ever you have the body work off and don't worry about it.

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    apriliaforum Junkie
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    Excellent

    100% for effort. 100% for quality. 100% for photographic reproduction.
    Superb example of what can be achieved with just a little 'extra' thought
    Dealer had to replace my water pump seal as it leaked from almost day one. When this was repaired??? the weep hole then started to pass oil!!!! So the bike was taken back (dealer collected) for another 'go' at effecting a cure. This time success, wish they'd seen your write up and photo's before they did my bike.

    Thanks again
    May the Gods of hot metal go with you and your Futura be bright!

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