Sherwood Raw Water Pump Noise

[Sharpseadog]

My 2007 Cummins QSB 5.9 has a Sherwood raw water pump that makes a "Gad awful" screech when the engine is started after it has shut down over night. Lasts for 30 - 45 seconds. I suspect it is running dry for that time. This is the 3rd pump and only has about 100 hours on it. Neither of the previous pumps did this. The Impeller was replaced last fall and probably has less than 20 hours on it and was installed by a certified mechanic. Is this common? Should I be concerned?

 

[Comodave]

The Sherwood pumps are a know problem. Check out Tony Athens website sbmar.com and buy a SMX pump. They aren’t cheap but he designed it around all the problems with the Sherwood pumps so the SMX pumps are solid. I have had them on my 6CTAs for about 3 years and no problems.

 

[Comodave]

Here is some info on the SMX pump.

SMX QSB Seawater Pump​

$995.00

Direct Replacement on all QSB 5.9 & QSB 6.7 Marine Diesel Engines
Price includes spare SUPER 27 impeller with puller, o-rings and gaskets

 

[jleonard]

I would open the raw water strainer cap, grease the o ring with vasaline and reinstall to make sure you are not sucking air into it.
If the squeal persists, get a SMX pump like como D suggested.

 

[Fletcher500]

I had a loud screeching sound like you described upon start up a few years ago. Figured it was a bad pully, pump, or other. I changed all of the belts, no improvement. Turns out the plastic belt guard at the front of the engine was a little too snug in one area and rubbing. Put a couple washers in between the screw head and nut, and that fixed it. I have the 6.7 not a 5.9 and it's likely not the source of your problem, just throwing it out there as some low hanging fruit to check. If it's your pump, the SMX is the way to go as others have described.

 

[Greg QS]

Another vote for the smx pumps.

I installed on my previous boat , 450c 's, They are still running. Nothing but impellers. 15 YEARS OLD !!!!!


Get them for both engines. NO BRAINER

 

[DDW]

SBmar periodically has these on sale. Every spring for sure, you've missed that, but other times in the year. If you sign up there you will get spammed when the sales happen.

 

[twistedtree]

Is the pump belt driven or gear driven? I have never heard of a pump squeezing like you describe, but certainly belts, typically when they are not tight enough.

 

[BlimpDriver]

My 2007 Cummins QSB 5.9 has a Sherwood raw water pump that makes a "Gad awful" screech when the engine is started after it has shut down over night. Lasts for 30 - 45 seconds. I suspect it is running dry for that time. This is the 3rd pump and only has about 100 hours on it. Neither of the previous pumps did this. The Impeller was replaced last fall and probably has less than 20 hours on it and was installed by a certified mechanic. Is this common? Should I be concerned? the pump was rebuilt or the impeller/impellers were changed twenty hours ago. My suspicion is that the impeller or at least one of the impellers was installed wrong at rebuild. Brand new they have enough resilience to manage to turn, even though they have the vanes pointed in the wrong direction. Now after sitting, the screeching you are hearing is very likely the belt that drives the pump. It screeches until it can get the pump turning. Once the pump is turning the water acts like a lube and relieves the tension formed when turning the impeller against its will.

Now there are plenty of salty dogs out there that will chime in and have an argument as to why that cannot be the case, have at it Mates. If you did the work yourself and you are not a full time mechanic, don't go hard on yourself, giving it another try will give you the answer. On YouTube there is a very good video showing the direction the vanes should be turning and how these pumps work. The video refers to a Jabsco pump, you will get the message. I hope this helps in some way.

 

[BlimpDriver]

Now there are plenty of salty dogs out there that will chime in and have an argument as to why that cannot be the case, have at it Mates. If you did the work yourself and you are not a full time mechanic, don't go hard on yourself, giving it another try will give you the answer. On YouTube there is a very good video showing the direction the vanes should be turning and how these pumps work. The video refers to a Jabsco pump, you this helps in some way.

It appears the start of my reply was cut off. A quick summation. 20 hours since rebuilding, suspect the impeller or impellers were installed wrong

 

[jgwinks]

Could be the new impeller is not sealing completely and allowing the water to flow back out during shut down. Sealing well enough to pump though. I've had a couple new impellers that were labeled as the correct ones but were slightly under sized and wouldn't seal or pump at all. Mislabeling or quality control problem. If it is dry at startup, it probably won't last long.