Raw water pump....started leaking..steady little stream..."how long til she totally fails?"

[YeOldeStonecat]

Probably an impossible question to answer. Pump itself 4 years old (both engines). New impellors this spring by the yard.

Replaced engine with a long block over the summer. During my 20 hour "break in" runs, noticed on the first day, bilge has water. Doesn't get deep, maybe 1/4 inch, since bilge pumps just shoot it out as it fills. Steady little stream comes out the bottom of the pump on this replaced engine when at higher RPM, but not at idle. Not going to get a replacement pump til mid next week but wanted to do short cruises this weekend to continue break in hours. Staying in fresh water river...as I don't want salt water spraying around from it.

Do they tend to take a long time to fail?

 

[Golfman25]

4 years seems like a pretty short time to start leaking. May want to check the easy stuff, maybe there's a screw loose???

 

[km1125]

It's not the leak itself as much as it would be what the leak is doing to the bearings. Eventually that leak will flush the grease out of one of the two bearings. The leak will also cool the bearing while it's running (as it runs out of grease and starts heating up) but the wear will increase until the bearing no longer functions as a bearing. But at this point it's an impossible question to answer.

Likely few people even notice that the pump is leaking slightly until there's already been damage to the pump and it needs to be replaced.

 

[kevin27]

Don't run it. Could fail any second but worse is water spaying the machinery.

 

[Hey Ray]

I had a stbd water pump go out and it sprayed water into my generator, had to remove the entire back end and get the stator rewound and re-installed. Very costly. I then got in the habit of looking around the engine compartment when engines were running, and soon noticed the port water pump dripping slightly. Replaced that right away.

 

[FootballFan]

If I saw that - I would replace "both" raw water pumps. The one leaking is about to fail at any time - the other one is the same age, so it may be approaching failure.

Normal day is 60-90 miles running off shore. I really don't want an engine shut down due to a water pump that blows a seal.

 

[km1125]

What kind of pumps are they (Sherwoods? Bronze? Plastic?).

You might think of replacing them but doing major rebuilds on them and keeping them for spares. Are they also belt-driven? Might be a good opportunity to consider changing to crank-driven type and eliminate the belt issue. That also could make replacing impellers SO much easier if you have space in front of the engines!

 

[Riptide III]

Leaky water pumps tend to leak on the engine mounts and rust the bolt. This tends to add a difficulty factor to other jobs. Transmission removal/ install. Very hard to align a tranny if the mount is frozen or rusted.

 

[Bill Curtis]

You have a picture of the pump?

The $64,000 question(s) here is (are) where is it leaking from? The shaft? The body flange / mating surfaces? The hose nipples? Is the pump body cracked? What kind of pump is it? Belt driven? Driven off the lower pulley?

Is there a blue colored water drain plug on the pump that is broken / fell out?

 

[Gallf1]

I had a similar leak on my port motor when I bought it. Unknown to me that at cruising speed it was spraying salt water all over my alternator. Went to start the engine the next week to go out and the alternator was rusted/fused.

The raw water pump was still able to produce enough cooling water but the alternator was shot.

When I removed the OEM Mercruiser raw water pump, I saw that water had made its way into the bearings which over time eroded the shaft and caused a wobble which at higher speeds let more water thru.

So, like others have stated it might not be the fail of the water pump that stops your engine!

 

[YeOldeStonecat]

Replaced Friday, didn't take a chance, new Mercruiser one...MSRP $570....just what I needed after all the money last month on the reman long block replacement.

5 years ago when we bought this boat I had the yard put in new raw water pumps in both engines, and every other year, replaced the impellors. So not a lot of hours on these pumps. Near as I can figure, I'm guessing that the bearings/seals don't like to have the load on them changed. They get used to the same exact position from the belt on the engine. Stick them on a new engine, the angle/load on the pully is slightly different..and premature failure. So when I replace the port engine next spring, I'll be sure to put a new raw water pump on that too!