water-pump failure? stealth coolant leak

[aelath]

Hey All,
I wanted to pick someone's brain about the coolant system.

In an effort not to bore anyone, here is my summary version:
- no major work done to the bike recently (no valve job, rebuild, etc)
- ~1 month ago after a ride I noticed drops of water dripping off the water-pump housing in 1 second intervals onto my exhaust. Ordered the water-pump face o-ring (92055A).
- 3 weeks ago I took my ninjette to the track (!!!)... after the first session I returned to the pit with a lower fairing full of water. Steady stream of drips from the water-pump housing, leak is getting worse.
- Degreased the area, removed the chain cover, warmed the bike up to inspect the leak location: it appears that the only wet spot is from where the liquid is pooling and subsequently dripping, on the bottom of the water-pump behind the face. This made me suspect the big o-ring (671D2535) for the water-pump shaft body that seals the pump to the crank case.
- Yesterday FINALLY got to work on the bike and I pulled the water-pump to discover what you all already know: the o-ring in question is to seal the oil, not the coolant. And it was in healthy condition.

Currently: I am puzzled. The leak appears to be connected to the water-pump housing, not the face o-ring (which I replaced). The leak manifests between the body of the water-pump and the crank case (no other places on the engine appear wet) AND when I loosen the water-pump housing bolts the leak *seems* to get worse. But there doesn't seem to be a coolant system o-ring connected to this indicated area

I went looking through the manual and I found an interesting section on the water-pump that may explain my issues. Its in section 3-6 and describes a mechanical seal inside the water-pump failing and how in an event of failure the coolant leaks out the bottom of the water-pump (see attachment).

Has anyone seen a water-pump fail like this? Should I just pull the trigger and replace the pump? Should I go back and keep looking for the source of the leak?

Thanks in advance!

[Triple Jim]

Originally Posted by aelath

Has anyone seen a water-pump fail like this? Should I just pull the trigger and replace the pump? Should I go back and keep looking for the source of the leak?

My 250 is the first water cooled motorcycle I've owned, but I've experienced this problems many times on cars. It requires replacing the pump on those vehicles.

The usual chain of events is:

1. seal starts to leak a little and drips out the relief hole, but isn't noticed
2. bearing gets grease washed out
3. bearing rusts and gets very loose
4. wobbling shaft causes the leak to get very bad, very fast
5. Jim has to repeatedly pour a couple gallons of water into the system every few miles to get home where he can replace the water pump.

The events may or may not be similar on our Ninjas, I'll let other tell us.

[Z1R rider]

We've (boys and myself) had leaks on the pipe, #32150 in this partsfish http://www.bikebandit.com/oem-parts/...9388#sch283627 (it's in the cooling sys. breakdown). All of these failures have happened at the track! The joint fails in the 90° bend at the bottom of the pipe, and it slow drips for a while and is hard to tell where it's coming from. Eventually it leaks much faster, enough to coat the rear tire, and then..........we don't use antifreeze at the track anymore! I took them off and soldered the joint to fix them, been holding for over a year now. But you could have a bad pump, just giving you something else to look at.

[Motofool]

Originally Posted by aelath

...........

Has anyone seen a water-pump fail like this? Should I just pull the trigger and replace the pump? Should I go back and keep looking for the source of the leak?

Thanks in advance!

Pump seals rarely fail and when they do, coolant leaks out through a hole in the pump body.

Please, see:
http://forums.ninja250.org/viewtopic.php?p=562758

That is the seal between the shaft ans body of the pump.
I don't know if the seal can be replaced.

[aelath]

Thanks Triple Jim, I actually forgot about my experience with water-pumps failing on cars... funny how zooming in on a problem causes that sort of effect. This all sounds familiar.

Originally Posted by Z1R rider

... The joint fails in the 90° bend at the bottom of the pipe, and it slow drips for a while and is hard to tell where it's coming from. ...

I appreciate the experience with the coolant pipe failures. I honestly expected one of these to be the issue, but the face of the pump housing is bone dry while water essentially pours from the bottom of the housing.

Originally Posted by Motofool

...
Please, see:
http://forums.ninja250.org/viewtopic.php?p=562758

That is the seal between the shaft ans body of the pump.
I don't know if the seal can be replaced.

I think this puts the nail in the coffin for me. Thanks for the link Motofool, I spent some time on ninja250 but for some reason I can never find this sort of content. (maybe I should search rather than browse?). Anyway, this corroborates the manual. The leak is definitely coming from this area, but I can't see the weep hole while the leak is in progress. It also makes sense that as I loosen the mounting bolts for the water-pump the weep hole would get a tiny bit more exposure and would explain my experience of seeing the leak intensify slightly.

Ugh, I guess I need to buy a water-pump. Thanks so much everyone!!

[aelath]

Just wanted to followup that it WAS the water-pump. I ordered a used in-good-condition replacement from ebay and replaced it 2 days ago. Filled the coolant, warmed it up and rode it around the block: zero leaks.

Thanks for the help!

[Petrolh34d]

Glad you got the issue figured out