Leaking impeller (not from the cover)

[Jim Cate]

Seals are cheap and the consequences of a failure of the water seal not caught early can lead to the oil seal failing and thus puts water in your engine oil with all the implications that has.

I agree that while apart, replacing both seals makes sense, but there is little danger of water getting into the sump via the inner oil seal on the shaft. There is a relief hole that vents water that gets past the water seal, and no water pressure is applied to the oil seal (whose task is keeping oil in, not water out!).

That relief hole is where the OP's drip was coming from...

And the bearings are pretty cheap, too, so replacing them if there is any corrosion or play is another good idea. I've been successful in pressing them on and off using a 4 inch bench vise and a socket wrench as a spacer.

Jim

[fcallard]

I had a water pump had been professionally rebuilt only a few years before it started to leak a serious amount of water when motoring. It turned out that the shaft was scored, necessitating another--but more complete--rebuild that included a new shaft. Hopefully the OP's pump shop will catch such an issue if it is there.

[Wotname]

Originally Posted by Jim Cate

I agree that while apart, replacing both seals makes sense, but there is little danger of water getting into the sump via the inner oil seal on the shaft. There is a relief hole that vents water that gets past the water seal, and no water pressure is applied to the oil seal (whose task is keeping oil in, not water out!).

That relief hole is where the OP's drip was coming from...
..........

Jim

Indeed!

And there should be a slinger on the shaft between the two seals about where the water vent hole/slot is located to ensure any leakage past the water seal is flung off the shaft before it can get near the oil seal.

The slinger need be no more than a snug O ring on the shaft.

[Jim Cate]

Originally Posted by fcallard

I had a water pump had been professionally rebuilt only a few years before it started to leak a serious amount of water when motoring. It turned out that the shaft was scored, necessitating another--but more complete--rebuild that included a new shaft. Hopefully the OP's pump shop will catch such an issue if it is there.

I have successfully repaired scored shafts with a "Speedi-Seal" (sp?). These are very thin s/s sleeves that tightly fit over the scored part, and thus restore a useful seal surface. cost about 20 AUD here in Oz, available from bearing supply houses.

Jim

[Mickeyrouse]

I’d like to point out that most marine diesel raw water pumps are Johnson, Sherwood, Jabsco, or Oberdorfer. OEM’s often don’t advertise the manufacturer, but it’s usually not too hard to suss out. Johnson pumps ( what Westerbeke currently uses) are often available on eBay for typically half of the discount Westerbeke price, and even cheaper if bought used. I carry a spare pump in case a problem requires more than an impeller. The old Atomic 4’s use Oberdorfer. Often the factory replacement impeller packaging will reveal the pump maker.

[Reefmagnet]

I used to believe that if water was dripping from the weep hole, no water would find it's way into the sump. Nek minut.....

[jannw]

If the shaft is damaged where the seal sits, then it will continue to drip with a new seal. This is a common problem related to sea water containing small amounts of grit which slowly wear away the point where the shaft and seal meet.

Replacement options include new shaft (Expensive), rebuilding the shaft (I guess you could do it with a tig welder and then re-machining), or the above mentioned SKF Speedi-Sleeve (Hint ... Answer is number 3!)

https://www.skf.com/group/products/i...-speedi-sleeve

The repair is documented by Sailbleu on the Jenneau forums on a Volvo MD22 engine:

https://www.jeanneau-owners.com/hint...waterpump.html

P.S. I feel your pain - I've already done 1 pump, and my spare is on the to-do list - I can confirm that the fix works and have put over 100 hours on the new pump without leak

[mrybas]

Update:
I got the pump back from Dempco. It cost about $130.
The exhaust water exits with much more gusto now and no more leaks!