Raw water pump leak...

rondds

Well-Known Member
Oct 3, 2006
8,859
Jersey Shore
Boat Info
2001 380DA
Engines
Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
I was poking around the bilge getting acquainted and noticed this rusty looking spot and a slightly rusty raw water pump pulley on the port engine. Looked over at the stbd and it was perfect and painted with no stain beneath...
100_3930_zps17614e81.jpg


Start the engines and check again and spotted a water droplet forming at the spot with the arrow. I haven't looked into it much further so I'm not certain where the water is originating from. If it's from the pump, what's going bad? The bearing? Spoke to a few people with the same pump and they have not encountered this. Anyone have a raw water pump fail/leak?

e054bdfc-4117-4f31-845c-67d2baf678d7_zps7ac40d21.jpg
 
The raw water pump on the boat is performing the same duty as the water pump on your car. I could be wrong, but the biggest real difference between them is that on the boat, the impeller is designed to be replaceable, while on the car it isn't.

But just as the water pump on your car will eventually wear out and start dripping coolant from the "weep hole", the one on the boat will do the same. That's due to the fact that there are still mechanical seals around the shaft and other moving parts in the pump to keep the water/coolant where it is supposed to be, and they wear out with use.

That's why the weep hole is there - it's designed to be an early warning of seal failure, before the unit dies completely.
 
src...thanks. I have replaced the impellers several times on my old boat but have never seen this pump fail or leak, nor has anyone else I've spoken to. I'm wondering if anyone else has experienced failure.

Each motor also has a circulating pump, which is the equivalent of an automotive water pump. My leak is on a different pump that is designed to pull seawater in to cool the motor. Cars use air to cool the coolant. Boats use seawater to cool the coolant. My "circulator pump" is fine. It's this raw water pump that's iffy.
 
I guess anything with a seal has the potential to fail. From the all that rust it is flinging around.

Clean the area to help with tracing the leak. Is it possible it could be coming from a hose that may be above? Pics don't show that area. If the leak is not easily traceable yu might try cleaning, then coating with a thin coat of vaseline and then sprinle baby powder over everything. Hopefully where the water is ciming from will be more eveident.

Just some thoughts. Good luck.
 
I have a similar (maybe the same) raw water pump on my 2004 300DA with 5.7s. I just had the impellers replaced for the third time. One pump had bad bearings and so we rebuilt it. The other was fine. My dock neighbor has a 2002 300DA and last fall one of his pumps started to leak and had to be replaced. The mechanic that just did my impellars said I should get new pumps with the next impeller change in three years. That would put them at 12 years old. So, if yours are original they may just be reaching the end of their natural life.
 
If I can confirm that the water is indeed coming from the pump bearing I'm likely going to replace with one of THESE. The boat was repowered in 2008 so if this is an original pump, it's going to be about 5 years old. Looks like a much improved design over Merc's. I have a friend who had them installed in his 320DA and he's very happy with them. I'll leave the stbd (it's fine) for now. Probably pull it and replace the impeller on that one while I'm at it.
 
If I can confirm that the water is indeed coming from the pump bearing I'm likely going to replace with one of THESE. The boat was repowered in 2008 so if this is an original pump, it's going to be about 5 years old. Looks like a much improved design over Merc's. I have a friend who had them installed in his 320DA and he's very happy with them. I'll leave the stbd (it's fine) for now. Probably pull it and replace the impeller on that one while I'm at it.

Just curious. Why not go with a crank mounted pump and save yourself the headaches? The impeller change becomes a 30 - 40 minute job for both engines.

Pump-Mounted-BIG.jpg


Priced out with the bracket and everything else, it's about the same as the stainless.
 
In the case of the 320DA, crank mounted pumps are not an option - there simply isn't enough room in front of the motors (at least with the genset installed). I agree they are a great option if you have the room for them.

I had a pair of the pumps Ron linked to installed this year. Cheaper than the OEM bronze pumps, built from 316 Stainless steel, and designed with internal wear plates...the mechanic that installed them was very impressed. They are solid and well made. Time will tell if they outlast the OEMs, but as someone that has replaced three sets of OEM raw water pumps over the last eight seasons, I was ready to try something new.

-CJ
 
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Has anyone rebuilt one of these pumps?
45000.png


I'm not finding a "rebuild kit" but the cost of #4 thru #9 above is around $100.00.
 
That's the same site I got my image above from. What exactly did you order from that parts list? #4,5,6,7? Thanks!
 
You might be better served buying one of the SS pumps that CJ found and using it as a replacement and rebuilding this one for your spares locker.

Just sayin'...
 
The raw water pump on the boat is performing the same duty as the water pump on your car. I could be wrong, but the biggest real difference between them is that on the boat, the impeller is designed to be replaceable, while on the car it isn't.

But just as the water pump on your car will eventually wear out and start dripping coolant from the "weep hole", the one on the boat will do the same. That's due to the fact that there are still mechanical seals around the shaft and other moving parts in the pump to keep the water/coolant where it is supposed to be, and they wear out with use.

That's why the weep hole is there - it's designed to be an early warning of seal failure, before the unit dies completely.
Just to set the record straight... the raw water pump is NOT performing the same duty as the water pump on your car, and there is no "weep hole". Now there is a circulating pump on our boats the is very similar to the one on your car and what you describe.
 
Just to set the record straight... the raw water pump is NOT performing the same duty as the water pump on your car, and there is no "weep hole". Now there is a circulating pump on our boats the is very similar to the one on your car and what you describe.

Thanks for clearing that up. Some of the later posts also made it clear there were two pumps.
 
Ron,

As far as I know this is sort of a common thing on diesel engines (at least Cummins, but I think others are similar) where around 1,000hrs mark the pumps start to go. Sometimes when one fails folks just do both b/c it's only a matter of short time before the other side goes. Having said that I've replaced both of mine. Wanna know the cost?.....no you don't....:lol:

I understand that we're comparing apples and oranges, but I think it's just a matter of age/hrs before gas engines get to the point of leaking water pump.
 
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Ron,

The pump rebuild is a piece of cake. I have a 30-tom hydraulic press in my shop, along with boxes of press and receiver rings, so if you want to come up and do it with me one weekend, I'll have my wife make lunch (This applies to other CSR members as well, but I'll need to see your membership card before approval) You might want to install the stainless one, then bring up the old one for a rebuild, and have it as a spare. Then, keep it as a spare, since you'll want a nice shiny stainless one on the other engine soon too...

At any rate, we can do the rebuild in a few hours, once you have the parts....

Dale
 
Thanks Dale. I ordered the SS pump and pulley. I'll get around to the rebuild at some point. I'll keep an eye on the stbd pump but right now it's in perfect condition.
 
Thanks Dale. I ordered the SS pump and pulley. I'll get around to the rebuild at some point. I'll keep an eye on the stbd pump but right now it's in perfect condition.

Carnac the Magnificent says:

carnac.jpg

It will fail the day before you leave for Atlantic City.
 
Or the day of....

Dale
 

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