Water pump mechanical seal and bearing

[ST-Traveler]

Need some advise on anyone having had experience with water pump and mechanical seal replacement.
I am getting a few drops directly out of the round weep hole above the square one. Shortly after start up. then it stops and no longer runs out while engine is running.
The service manual states this is a sign of the water pump mechanical seal failing and needs to be replaced.
My question is the manual states to replace the water pump as an "assembly" but the parts fiche shows 2 different parts. The Mechanical seal 19217-MAL-300 and IMPELLER, WATER PUMP 19210-MCS-000.
Has anyone replaced the mechanical seal as an assembly or do you have to buy the impeller and seal and press them together and then press them into the crank case cover ?
I am confused on what the service manual also states. It states to remove the water pump cover and press out the water pump impeller?? but you have to remove the crank case cover as well as the water pump cover right?
My other question is how long can it go like this? Is this an immediate fix needed type thing?
Thanks for any advice and help in advance.

 

[ST11Nut]

I haven't replaced a ST1300 water pump myself

I found a couple threads that you might find useful

New Water Pump... | ST1300-Leaks

I found coolant seeping out of the water pump weep hole today; it looks like the water pump seal has gone out. The parts should show up early next week, and it doesn't look like too much of a job. The shop manual says to replace the whole unit, which makes sense if I'm taking things apart...

www.st-owners.com

Article [13] - ST1300 - Water Pump Weep Holes | ST1300 Articles

There are two 'weep holes' on a ST 1300 motorcycle. They serve entirely different purposes and have nothing to do with each other. Because the two outlets (the "round hole" and the "square hole") are located very close together, this sometimes causes confusion. I'm not sure which hole you are...

www.st-owners.com

 

[CYYJ]

Need some advise on anyone having had experience with water pump and mechanical seal replacement.

I've disassembled everything in the area of the water pump, and removed the water pump (attached to the front engine cover) from the motorcycle, but I have not actually replaced the water pump. I'll tell you what I know about the disassembly required to get to the water pump.

The article cited above (ST1300 - Water Pump Weep Holes) contains photos of my ST 1300 when I took it apart this past winter. It is not at all a difficult job to disassemble the bike to get the water pump out - in fact, it's pretty simple work. A lot of disassembly, for sure, but none of it is complex. It is a very time-consuming task because of the level of disassembly needed - if you are not planning on doing any cross-country rides this year, and the leak rate remains constant at just a few drops per warm-up cycle, you might want to defer this job until the wintertime.

If you can, start work with an empty fuel tank (2 bars or less) - this gives you the option of removing the upper fuel tank later on if you decide you want to go in and replace coolant hoses.

It's pretty much essential that you have a ST 1300 Service Manual to do this job, simply because there are so many other parts that need to be disassembled to get at the water pump, and a lot of the fasteners have torque specifications.

Go to the grocery store and buy a tube of about 25 paper cups. I find it very handy to put the fasteners I remove from each 'item' (body panel, brake unit, etc.) in a cup, and write the name of that component on the inside of the paper cup - saves figuring out what fastener goes where later on.

Put the bike on the side-stand, then remove the oil plug from the bottom and drain the oil out. Don't worry about getting all of it, you will have ample opportunity to get rid of every last drop later on.

Put the bike on the center stand, jack it up a wee bit at the front to lift the front wheel two inches off the ground, then shove a block of wood under the oil pan to hold the bike in place (don't trust the jack). Remove all the lower Tupperware (pebbled black finish around the bottom of the motorcycle). Remove the mirror covers, mirrors, and the two big Tupperware pieces on either side that say "ST 1300" on them. Remove the front wheel (not 100% essential, but it sure makes the rest of the work a lot easier - I would say 99% essential).

Drain the coolant out of the engine by disconnecting the lower radiator hose. Disconnect the other radiator hose and then remove the radiator.

Now, while facing the engine (in other words, while standing at the front of the bike, looking back towards the engine), remove all the little bolts that hold the water pump cover on (see photo below, showing water pump cover removed). Once you have removed that cover, remove the rest of those little bolts and take the front crankcase cover off. The water pump is embedded in the front crankcase cover.

Now that you have the front crankcase cover with the water pump embedded in it in hand, you can get going on replacing the water pump. I have never done this, but there is an excellent article on a blog here: Front cover removed and the clutch exposed... that explains what has to be done. You will need some specialized tools (a press), and measurements are critical, which means you absolutely, positively need to have a ST 1300 service manual on hand. You might choose to sub out the work of removing the water pump from the crankcase cover and installing the new pump in the cover to a machine shop if you don't have the specialized tools, or if you are not at ease doing this yourself.

Once all that is done, you could just put everything back together. But, considering that your bike is 11 years old, it would be very prudent to replace the thermostat while you are in there, and consider replacing some of the hoses attached to the thermostat housing. Also, snug up the clamps on all the hose clamps.

Michael

Water Pump Cover Removed

 

[ST-Traveler]

Once all that is done, you could just put everything back together. But, considering that your bike is 11 years old, it would be very prudent to replace the thermostat while you are in there, and consider replacing some of the hoses attached to the thermostat housing. Also, snug up the clamps on all the hose clamps.

Hi thanks for all the info, - This past winter I did an alternator, all water hose, thermostat, temp sensor, oil pressure sensor and clutch replacement and had the engine torn down pretty far. I have the crank case cover off now and will order the parts on Monday. I am recording all the impeller measurements to match up with the old one. Larry Igofar recommended an arbor press from harbor freight. may go that route.
I am planning on re-using my crank case cover gasket and water pump cover "O" ring as it only has about 500 miles on it now and they are OK upon inspection unless you can think of a reason I should replace anyway.
Of all the work I have done to my bike so far this is one of the more tricky projects because you have to press bearings and impellers and can't just buy a part and slap it on the bike, you have to actually do some type of mechanical work by means of a bearing press etc..

 

[CYYJ]

...Of all the work I have done to my bike so far this is one of the more tricky projects because you have to press bearings and impellers...

I agree with you. The disassembly and reassembly is time-consuming, but it is very simple and straightforward. The business about pressing the water pump in and out would scare me a bit.

Apropos of the seals... if the water pump O-ring is still perfectly round in cross-section everywhere, maybe you could get away with re-using it. But, I think a new one is only about $16 or so - it would be a shame to get everything back together and then have a 'square hole leak' due to a tiny imperfection in the seal of that O-ring.

As for that paper gasket, I think you can trust your own judgement after doing a visual inspection.

Michael

 

[ST-Traveler]

Mechanical seal removal- The service manual states to press out the impeller using a hydraulic press- The it says to remove the impeller housing bearing using the "special tool" but then it says to just remove the mechanical seal- just wondering since you have to press the mechanical seal in using a hydraulic press then do you have to press out the old one also or does it just fall out some how?