2015 FJ-09 coolant leak at water pump

[Forevertwowheels]

Hi everyone,

2015 FJ-09 with 14k miles. Likely original coolant as well.  I searched for an answer on this and other -09 forums with no clear answer. 

While performing an oil change yesterday I found evidence of coolant weeping or leaking from the weep hole at the bottom of the water pump (in the form of very distinct white dried residue from coolant).  Coolant reservoir and radiator were full, no measurable loss in the 5k miles I’ve owned it)

I removed the water pump to confirm this is where the coolant was leaking (it was, circled in Orange in attached photo)

How to repair? I assume the mechanical seal (#7, pn 5VK-12438-00-00) is the culprit. Now my questions. Obviously I’d like to avoid replacing the entire pump as it’s pricey ($170). 
 

1. Can I replace the mechanical seal (5VK-12438-00-00) only without special tools?  If the bearing doesn’t require a hydraulic press to remove I’m sure I can get it off without damaging the shaft. 

2. Is there risk that the shaft is the culprit and not the seal?

3. Is some weeping normal?  It’s possible the coolant residue was there since the bike was bought by me. Any risk in just keeping an eye on it?

I can buy a new water pump (and may do so) for peace of mind but if it’s not required I’d rather not. 

[peteinpa]

I'd wipe it clean but keep an eye on it.

True story:  On later year Honda ST1300's they attached a hose at the weep hole that ran to the ground.  Would have to be gushing for you to know.

[bwringer]

I have not fooled with the FJ's water pump specifically, but the same basic design is used on lots of other bikes.

Anyway, unless you have a long trip planned, watch and wait is a valid strategy. Sometimes mechanical seals get a wee particle or something in there, and then "cure" themselves. They generally don't fail catastrophically. I'd wipe it off and see what happens.

That said, the other failure mode is if the bearing is damaged, worn, etc. the shaft can wobble around and damage the oil seal. Sometimes the shaft is salvageable, sometimes it's best to replace it. In other words, unless you have lots of other bikes and you're so cheap that a $21 impeller is worth possibly missing a week or more of riding, I'd just order all the moving parts in one go and get it over with.

1) Yes, you can replace the mechanical seal without special tools. Once removed, you have to replace it.

2) Depends on mileage, somewhat. Damage to the shaft would be more likely to cause damage to the oil seal and cause an oil leak. A water leak indicates the mechanical seal has an issue.

3) Yeah, kinda, once in a while. Run it for a bit and see what happens. But if it continues or doesn't stop. order up the parts pronto.

 

I'm seeing about $141 for the assembly (plus another $4 for that one o-ring, #17), which ain't bad at all. To do a proper rebuild, you'd want the impeller, bearing, oil seal, mechanical seal, circlip, all the o-rings, and the gasket washer. That's $94.01, so honestly only about $50 more for a whole fresh assembly ready to go is pretty appealing, and that's what I'd do.

https://www.onlinecycleparts.com/oemparts/a/yam/546a26caf87002164cb28014/water-pump

 

Edited May 27, 2022 by bwringer

[micah2074]

Mine leaked a tiny bit from the drain. It’s close to where you circled. Tightened the drain a bit and it stopped. It wasn’t much more than finger tight. 

[Buggy Nate]

You can get away without replacing the shaft. They usually last a very long time. I would definitely be replacing the seals and o rings and inspect shaft when removed. They are easy to replace. Just take not of seal direction etc and maintain squareness when pushing seals into required depth.

[nhchris]

Seven year old coolant isn't cool!  So I assume you'll be replacing it as part of reassembly.  You might find fresh coolant leaks more, or even less.  Interesting to see.

My 2016 FJ  needs all the coolant flow it can get as the engine runs very hot when summer arrives.  Not unusual to be floating around the boiling point in traffic.  So the water pump is a REALLY important subsystem. If it were me I'd spend the $170 for peace of mind.

There are a lot of wrenches on this forum who'd dig into that water pump in a heart beat. But as I look at the diagram you posted there are way too many seals gaskets and other bits to foul up during reassembly.

Look at it this way... These days $170 is only a few tanks of premium!

Edited May 28, 2022 by nhchris

[Forevertwowheels]

Thanks everyone for the advice. Since I am alert but not alarmed everything went back together with new coolant for now until I decide to repair or replace. No signs of leaking on 50 or so miles since. Fortunately the pump is easily accessed on this bike. I will follow up in the coming days with an update. 

@bwringer I do have a long ride planned next week so that is a factor. Thanks for the tips. 
 

[peteinpa]

This is a good point to mention about a ECU tune.  Not only can the fan temps be lowered but a lean running engine runs hot.

[KrustyKush]

In 97 I bought a new Yamaha Royal Star. Before I rode it I saw a trickle of coolant at the weep hole. They replaced the water pump within the hour (so they said) but the new pump also leaked the same way. Brand new, mind you. I rode that bike for 75k miles, then sold it to another guy who had over 100k on it last time I saw him. All the while, it would weep out a tiny bit of coolant from time to time. I have also seen this on a couple other bikes, mainly Hondas. Seems like every Honda I owned got a new water pump the first year. But a bit of seepage should not cause concern. 

[bwringer]

The mechanical seals in these water pumps don't really work the same as the rubber oil seals we're accustomed to; they're basically two discs of very hard, smooth ceramic held together with a spring, and once in a while a tiny particle can get in there, or you can get a tiny bit of seepage after the vehicle sits for a long time. 

You can't use rubber "lip" shaft seals because antifreeze is slightly abrasive, and a rubber seal would fail in short order. In pumps like this, the oil seal is there to keep engine oil away from the antifreeze. There's a wee chamber in between with the weep hole so that AF can't get to the oil seal.

Anyway, car water pumps can also eject a few drops once in a while but the engine is hidden so no one ever notices unless there's a bigger problem.

Maybe that's why I'm always slightly suspicious of cars -- you can't see the engine and what it's up to as easily. A motorcycle with the engine exposed is more honest.

[Forevertwowheels]

Update: road trip complete, approximately 1200 miles done over the weekend. I did it on the stock water pump and seals only changed the coolant. No leaking. I plan to keep it the way it is until something changes.

I learned that I want to flash the ECU to lower the fan temp and remove the ridiculous 115mph speed limiter. 
 

cheers

[knyte]

Sounds like  you've solved it!

In case the need arises, here's a link to all the o-rings and crush washers you might need - they're easy to swap out.