Raw water pump leaking

[drprunner]

I have a slow (1 drop every 15-20 seconds) leak in my Cat 3116 raw water pump. It's leaking from the bottom oblong hole in the pump. The pump is 3 years old and the impeller is 4 months old. The pump seems to work fine otherwise, no cooling issues. If it wasn't for the surface rust on the engine mount underneath it, I might not have noticed it. Any ideas?

 

[FootballFan]

I would replace it, at a minimum replace the seals if that can be done.

 

[Express 390]

I have a slow (1 drop every 15-20 seconds) leak in my Cat 3116 raw water pump. It's leaking from the bottom oblong hole in the pump. The pump is 3 years old and the impeller is 4 months old. The pump seems to work fine otherwise, no cooling issues. If it wasn't for the surface rust on the engine mount underneath it, I might not have noticed it. Any ideas?

View attachment 79398

Yes the seal is gone they need to be replaced

 

[drprunner]

Yes the seal is gone they need to be replaced

What seal ??? I replaced this pump 3 years ago and with my old pump as a core it was still $600. Can I just replace the seal??

 

[Soulshine]

What seal ??? I replaced this pump 3 years ago and with my old pump as a core it was still $600. Can I just replace the seal??

The shaft seals.

There’s only 2 places it can leak assuming that the housing isn’t cracked.

The shaft seals or the housing cover gasket. You opened it up 4 months ago to replace the impeller, so the latter is a good bet.

 

[Express 390]

I have a slow (1 drop every 15-20 seconds) leak in my Cat 3116 raw water pump. It's leaking from the bottom oblong hole in the pump. The pump is 3 years old and the impeller is 4 months old. The pump seems to work fine otherwise, no cooling issues. If it wasn't for the surface rust on the engine mount underneath it, I might not have noticed it. Any ideas?

View attachment 79398

What seal ??? I replaced this pump 3 years ago and with my old pump as a core it was still $600. Can I just replace the seal??

Don't take this the wrong way But from the look of it that didn't just start thats been leaking for a while and at the First sign of any corrosion it should be looked at, wire brushed, and painted. Its a possibility The belt is too tight which could cause the seals to give out so soon. Thats if it is belt driven?

 

[fwebster]

The seawater pump on Cat 3116's is gear driven off the accessory drive.......you will look a long time before finding a belt.

I'm betting that the pump seal was either faulty or improperly installed before you got the pump. It is a pain, but I would go back to the vendor you bought the pump from and tell them you got a defective one and (politely) ask them to replace it.

Another thing to consider it to never buy a seawater pump or impeller from just any cheap online vendor. There is no telling how long the pumps or impellers have been sitting on a shelf in a warehouse drying out. Always buy from a volume dealer big enough to cycle their inventory.

 

[drprunner]

Don't take this the wrong way But from the look of it that didn't just start thats been leaking for a while and at the First sign of any corrosion it should be looked at, wire brushed, and painted. Its a possibility The belt is too tight which could cause the seals to give out so soon. Thats if it is belt driven?

It has been leaking for awhile, and it is gear driven, connects directly to the flywheel. So it's the shaft seals? Can they be replaced?

 

[ttmott]

It's leaking because it wasn't painted Cat White; very bad JuJu...
There are two shaft seal assemblies one for the engine side for oil sealing and one on the pump side for water sealing. The hole is specifically there for the event of one of the seals failing so water doesn't get in the engine (for example). If that was a new pump and the shaft is in new shape then you can install a Sherwood Major Repair Kit which is widely available. But, regardless paint the pump...

 

[dtfeld]

What seal ??? I replaced this pump 3 years ago and with my old pump as a core it was still $600. Can I just replace the seal??

Yes...and No

You can buy a rebuild kits for these pumps, both seals kits and major rebuild. Pretty expensive parts, especially if you need a new shaft.

The risk on these pumps it that any leaks through the forward seal, will put sea water into the engine oil ( the drive gear is lubed by engine oil). You can guess the result of that.

By my calculus, new pumps every 3-5 years is the price of ownership. $600 is cheap compared to new engines.

 

[FootballFan]

Pretty straight forward issue.

 

[my3sons]

Yes...and No

You can buy a rebuild kits for these pumps, both seals kits and major rebuild. Pretty expensive parts, especially if you need a new shaft.

The risk on these pumps it that any leaks through the forward seal, will put sea water into the engine oil ( the drive gear is lubed by engine oil). You can guess the result of that.

By my calculus, new pumps every 3-5 years is the price of ownership. $600 is cheap compared to new engines.

I think ttmott is correct about the inability of a fluid leak to get from one side to the other because of the “windows” that the fluids appear at when one if the seals begins to fail.

 

[dtfeld]

I think ttmott is correct about the inability of a fluid leak to get from one side to the other because of the “windows” that the fluids appear at when one if the seals begins to fail.

Because of the "window" sea water under pressure is not going to force its way into the oil. Murphy's Law being what it is, I could see a little bit weeping through a bad front seal and into the oil while running or even after shut down. I think the possibility of this is low, but it would also be impossible to identify until too late. While these pumps are expensive, I think it cheap insurance compared to the cost major engine repairs.

Faced with the same issue on one pump last winter I purchased 2 new ones.

 

[dtfeld]

Just looked. Major rebuild kits are $312 (on sale). Reman pump from CAT are $470 and come with same warranty as new part.

If you have the tools and knowledge you can save $150 per engine. Nothing magic about these pumps. I have the ones I pulled and have considered rebuilding myself, just not sure its worth it.