Raw Water Pump Failure

Jcclark85

Jcclark85

Member
Dec 16, 2019
32
Boat Info
2002 Sundancer 360
Engines
8.1S Horizons
When back in our marina from a couple days on Put-in- Bay. I went down into the engine compartment to just look around as we had a pretty rough ride down and back. I noticed a couple drops of water on my waste tanks vent filter and thought it was odd, stared at it a little longer and then realized there was vertical water mark on the side of my waste tank itself. So go exploring a little more and find my port engines raw water pump is dripping water from a broken bearing seal onto the pulley wheel which is then getting on the belt and the water is being slung up the side of the waste tank. Anyways, I pulled the pump (pain the @ss on port side engine basically laying on top of the engine hanging upside down) and purchased a new pump and figured I’ll rebuild the old pump and keep it as a spare in case of another failure. So I started pulling the old pump apart today and this is what I found. The inner bearing was completely destroyed. And the outer casing of the inner bearing had siezed to the inner wall of the pump. I had to tape one end of the pump and fill it with PB Blaster to hopefully free it so I can rebuild. What’s crazy is I have no idea how long that’s been like this, we had a 4.5hr ride home at 23 knots and didn’t get an alarm or notice any engine temp increase or see any steam coming from the exhaust. Just sharing as if I had not noticed those couple drops I would not have noticed the issue.
 

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CAn you cut the outer race with a hack saw?

Once you get close to cutting through it, it should collapse on itself and drop right out.

Another method used with automotive wheel bearings is to weld a bead right onto the bearing surface all around the race. It’ll cool relatively quickly and shrink the race enough that it’ll pop out.
 
Or put the whole thing in an oven, get it nice and hot. Then pull it out and spray some "spot cool" on the race to make it shrink and break the bond between the race and housing.
 
suggest check combustion air inlet silencers on all engines that were running. most likely you will find salt
 
Good on you for looking deeper. What an unnerving feeling when you see just how close you were to a total meltdown! 'Reminds me of my wheel bearings:
C0-FDE156-9-BD0-4-F42-AC2-A-7-FC5-CD32-E98-B.jpg


@Espos4 nailed it. Assuming you have access to a MIG, merely run a bead around the inside of the outer race. Doing that with my wheel bearings shrunk the races to the point where one just plain fell out of the hub when it was flipped over.
 
scoflaw said:
That brass water pump is nothing but trouble. SS harden marine way to go
Click to expand...

I thought it was brass, too, from the pictures.
Hardin S/S is the go to pump, IMHO.

Have has 3 of them on BBC Bravo's and never once did one fail.
 
Cast bronze not brass.
You'll never cut that bearing race with a hack saw - it needs to be either pressed out or ground through with a grinding stone in a dremel. I think you have a great plan to rebuild as a get home spare but can you get a complete shaft/bearing/seal kit for it?
 
Regardless of the alloy they are referred to as brass but the problem is it's soft that's why the shafts walk out. They score easily and your not fixing that. Metaltec makes some wear plates for it, but why bother when there are better options.
 
scoflaw said:
Regardless of the alloy they are referred to as brass but the problem is it's soft that's why the shafts walk out. They score easily and your not fixing that. Metaltec makes some wear plates for it, but why bother when there are better options.
Click to expand...
Agree on replacement but for a emergency get home backup that he is wanting it's a great solution. How can the shaft "walk out"? isn't it pressed onto the bearings? Or are you saying the bearings walk out? In his scenario it looks like the seals failed then corroded the bearings and the bearing failure but, the outer races are still in place in the pump housing. Right?
 
ttmott said:
Agree on replacement but for a emergency get home backup that he is wanting it's a great solution. How can the shaft "walk out"? isn't it pressed onto the bearings? Or are you saying the bearings walk out? In his scenario it looks like the seals failed then corroded the bearings and the bearing failure but, the outer races are still in place in the pump housing. Right?
Click to expand...
Agree his didn't walk out but that is a common failure with this pump. The outer race that he's trying to get out comes loose from the pump body and every thing moves as an assembly. Some recommend staking the body after a shaft assembly replacement.
 
scoflaw said:
Agree his didn't walk out but that is a common failure with this pump. The outer race that he's trying to get out comes loose from the pump body and every thing moves as an assembly. Some recommend staking the body after a shaft assembly replacement.
Click to expand...
Interesting thanks. There are bearing adhesives for machinery also.
 
Mercruiser acknowledged the bad design and introduced another similar one that uses wear plates but also needs their narrower impellor
 
Change both engine pumps. The other will not be far behind that one. I had a pump fail on my 300da in the Keys years ago and it took hours to clean everything in the engine room from the salt. Changed the failed one there and the other as soon as I got home. It was starting to go as well.
 
I saw the Hardin option but went with mercruiser standard pump because my mechanic had one in stock and I had guests coming over so needed a quick turnaround. The new mercruiser pump looks like it has a wear plate in it. As far as the old pump, I had to apply a torch to the side and a couple blows to get the siezed outer bearing out. I don’t see any damage to the inside wall so I’m going to rebuild it and keep it as an emergency pump..
 
Had the same thing happen a few months back. Definately replace both pumps and I was strongly advised by the dealer and my mechanic to buy new versus a rebuilt. It costs more but you'll have peace of mind that they wont crap out after a couple months. Mine cost @$900 each after negotiating a discount with the dealer. Good luck.
 
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