Cat 3126 raw water pump

Rssll45

Rssll45

Member
Feb 16, 2009
87
New Orleans
Boat Info
1998 450DA
Engines
Cat 3126
We all agree that the impeller on the stb engine pump is a bitch to replace. I was at the
Work Boat Show in New Orleans a couple of weeks ago and looked at an exhibit by JMP Products, a Korean mfg who makes a plug and play replacement for the Sherwood pump that has a spline shaft instead of a key. The impeller also has the threaded end for the bolt puller. This would take a lot of the#!%$#out of the impeller replacement. Just wondering if anyone has used this pump and has a comment on its service?
 
Never been in the bilge of a 450, but the best way to do the starboard impeller on my 410 is to remove the exhaust.
Even if there was a spline as opposed to the Sherwood pump I would still need to remove the exhaust to get the job done.
 
The impeller for a Cat 3196 is threaded. I insert a long bolt in it and just unscrew. It is really simple. Now getting to my part impeller is another nightmare.
 
JVM225 said:
Never been in the bilge of a 450, but the best way to do the starboard impeller on my 410 is to remove the exhaust.
Even if there was a spline as opposed to the Sherwood pump I would still need to remove the exhaust to get the job done.
Click to expand...
Sorry to hear that... Starboard may be a bitch but I don't have to remove an exhaust...
 
Depending upon the condition of your knees, the stbd impeller on a 450DA isn't that bad to get to. You just have to "get back there with it" and park yourself against the water heater. An old boat cushion under your knee helps a lot. Also, the faster you work, the fewer Advils are required to get over the impeller job.

I made my own impeller removal tool by buying a piece of grade 8, 3/4"-16tpi all thread rod then shaping one end on the lathe in a slight dome to avoid scarring the back of the pump housing. I drilled the other end of the all-thread to accept a 1/4" drive socket so the square end fits flush with the end of the all thread and then turned the end of the socket to get rid of most of the hex end. Last, the socket was pressed into the end of the all-thread and then brazed in place so the socket and brazing are smaller in dia. than the all thread rod. With a 1/4 ratchet and a short extension, I can jack the impeller completely out of the pump housing by running the tool all the way thru the impeller or at least far enough that it falls out in your hand.
 
JVM225 said:
Thinking of treating myself to the impellertool that was mentioned in other threads to at least make the job a slight bit easier once I get to the pump.
Click to expand...

Let me know how it work...$90.

As bitchy as it is, I’m pulling the pump from the engine, and doing it on my bench.

The oil gallery on my engines prevent good/easy access. So for me 2 reasons to just pull the pump. One, it’s just easier, but two, any water coming in around the shaft seal might be appearant before it bleeds a bunch of water into the engine oil.

D35D8FDA-1C0B-4BE5-B790-C442CB65D8B9.jpeg
 
Last edited:
So no one has installed a JMP pump. I don't have a problem getting the impeller out. with the puller bolt, although it's slow work, it's getting the new one in-aliening the key and pressing the impeller in place. I put a new Sherwood pump on two years ago and on it the keyway slot is not cut to the end of the shaft making alignment even more difficult. Just think having a spline shaft would greatly simplify the job. I may try the JMP pump. If it works, I'll let you know.
 
dtfeld said:
Let me know how it work...$90.

As bitchy as it is, I’m pulling the pump from the engine, and doing it on my bench.

The oil gallery on my engines prevent good/easy access. So for me 2 reasons to just pull the pump. One, it’s just easier, but two, any water coming in around the shaft seal might be appearant before it bleeds a bunch of water into the engine oil.

View attachment 78022
Click to expand...

Dave,
I’ve only done the impellers once, but I just removed the sender so there was more room to work with the impeller.
That’s my plan this time too
Don’t think I would be able to get the old impeller out with the sender in the way.
If we don’t get a few warm days over the winter I may go with FrankW’s method for the starboard impeller this year and just pay the guys in the boatyard to do it.
They could get the one in the generator at the same time.
The job is a lot less terrible with the exhaust out of the way, but last time I took it off to do the impeller it was a knuckle buster.
 
Rssll45 said:
So no one has installed a JMP pump. I don't have a problem getting the impeller out. with the puller bolt, although it's slow work, it's getting the new one in-aliening the key and pressing the impeller in place. I put a new Sherwood pump on two years ago and on it the keyway slot is not cut to the end of the shaft making alignment even more difficult. Just think having a spline shaft would greatly simplify the job. I may try the JMP pump. If it works, I'll let you know.
Click to expand...

Maybe you could bump the motor so the slot in the shaft is up top, put the key in the slot and hold it in there with a little glob of grease.
Use either tie wraps to compress the blades on the new impeller or try the impellertool that a few have mentioned to do it.
That might make it easier for you.
 
carterchapman said:
$196.70 for the install tool...
Click to expand...

Yikes!!!!
I wonder if you could accomplish the same thing with a short piece of PVC with smoothed out edges.......
Maybe something with the right size inside diameter to fit the impeller and an outside diameter to line up just inside the housing.......
Might take a little longer to compress the impeller in to the PVC than it would in the video for the tool, but if you could do it on the bench and bring it pre-loaded in to the bilge it might work out.
 
fwebster said:
Depending upon the condition of your knees, the stbd impeller on a 450DA isn't that bad to get to. You just have to "get back there with it" and park yourself against the water heater. An old boat cushion under your knee helps a lot. Also, the faster you work, the fewer Advils are required to get over the impeller job.

I made my own impeller removal tool by buying a piece of grade 8, 3/4"-16tpi all thread rod then shaping one end on the lathe in a slight dome to avoid scarring the back of the pump housing. I drilled the other end of the all-thread to accept a 1/4" drive socket so the square end fits flush with the end of the all thread and then turned the end of the socket to get rid of most of the hex end. Last, the socket was pressed into the end of the all-thread and then brazed in place so the socket and brazing are smaller in dia. than the all thread rod. With a 1/4 ratchet and a short extension, I can jack the impeller completely out of the pump housing by running the tool all the way thru the impeller or at least far enough that it falls out in your hand.
Click to expand...

I like that idea better than the plastic tool that Sherwood sells!
 
JVM225 said:
Yikes!!!!
I wonder if you could accomplish the same thing with a short piece of PVC with smoothed out edges.......
Maybe something with the right size inside diameter to fit the impeller and an outside diameter to line up just inside the housing.......
Might take a little longer to compress the impeller in to the PVC than it would in the video for the tool, but if you could do it on the bench and bring it pre-loaded in to the bilge it might work out.
Click to expand...
That's EXACTLY what I was thinking!!! Mine is 3 1/2" in diameter...thought I'd try a 3" piece of PVC...
 
You do this every 2-3 years, not often enough to go to extremes over. What is wrong with twisting the impeller then holding the blades with a couple of zip ties and using silicone lubricant or dish soap for a lubricant, align the key and insert the impeller and clip the zip ties as you push the impeller home ?

And, here is a tip.........use some 400 grit wet or dry sandpaper to polish key paying special attention to the square corners thus removing any small burrs from the machining process.
 
fwebster said:
You do this every 2-3 years, not often enough to go to extremes over. What is wrong with twisting the impeller then holding the blades with a couple of zip ties and using silicone lubricant or dish soap for a lubricant, align the key and insert the impeller and clip the zip ties as you push the impeller home ?

And, here is a tip.........use some 400 grit wet or dry sandpaper to polish key paying special attention to the square corners thus removing any small burrs from the machining process.
Click to expand...

Precisely what I've done
 
fwebster said:
You do this every 2-3 years, not often enough to go to extremes over. What is wrong with twisting the impeller then holding the blades with a couple of zip ties and using silicone lubricant or dish soap for a lubricant, align the key and insert the impeller and clip the zip ties as you push the impeller home ?

And, here is a tip.........use some 400 grit wet or dry sandpaper to polish key paying special attention to the square corners thus removing any small burrs from the machining process.
Click to expand...

Mine gets done every other year. I used the zip ties when I did them the first time two years ago.
The pump on the port motor was no problem because I had plenty of room to work comfortably.
But the starboard side on my 410 is a whole lot harder to deal with. Even with the exhaust removed I was in an awkward physical position wedged between the motor and the generator while working the impeller in to the pump.
Between wrestling with the starboard exhaust hoses and then the impeller I’m deciding between either having the boatyard do it or springing for the impellertool.
I’m leaning towards paying the boatyard to do the job. The only thing holding me back is that if I do it myself I can do some cleaning and touch up over the course of several sessions on the outboard side of the starboard motor while I have the exhaust hose off.
 
It is worth removing the starboard exhaust as well as the aluminum hatch channel. Once those are removed it makes it way easier although it helps if you can work well with just your left hand! Also pick up a cheap chase lounge pad to throw over the top of the engine to keep from bruising your chest.
 
Our marina and boat yard are owned by the local Sea Ray servicing dealer. They work on enough Sundancers in the 28 to 40 ft range that they understand how important access is. One of the things they have done for years is to employ a couple of smaller, very fit mechanics and they pay health club dues for the mechanics. As a result we have 2-3 guys who can get to about anything on a boat. Last year, I had them change my impellers to give my again knees a break. I just looked at the work order and the labor charged for both sides was 1.25 hours and the impeller kits were $58 ea. + freight.

Money well spent....!
 
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