5.0 MPI seawater pumps

D

DaleM

Member
Aug 5, 2009
690
Mt Airy, MD
Boat Info
340 Sundancer
Engines
Twin 8.1 Horizons
I'm planning on replacing my seawater impellers this winter. I spoke to Mercruiser customer service who said the only thing available that is typically replaced for my serial numbers are the impellers and the associated o-rings.

I know the pump housings are plastic. She said the housing is not typically replaced unless there are groves in it from wear.

I'm not doubting their expertise but I thought there was a kit available that provided the impeller, o-ring, and the plastic housing. She said the only way I could get the housing was essentially to replace the entire pump (@$350). I'm not sure if I need a housing or not but figured if there was a way to transfer the bearings, seals, shaft, etc to a new housing I'd go forward and do it.

Please let me know if others have had heard otherwise.

Thanks!
Dale
 
DaleM said:
I'm planning on replacing my seawater impellers this winter. I spoke to Mercruiser customer service who said the only thing available that is typically replaced for my serial numbers are the impellers and the associated o-rings.

I know the pump housings are plastic. She said the housing is not typically replaced unless there are groves in it from wear.

I'm not doubting their expertise but I thought there was a kit available that provided the impeller, o-ring, and the plastic housing. She said the only way I could get the housing was essentially to replace the entire pump (@$350). I'm not sure if I need a housing or not but figured if there was a way to transfer the bearings, seals, shaft, etc to a new housing I'd go forward and do it.

Please let me know if others have had heard otherwise.

Thanks!
Dale
Click to expand...

Dale, your pumps are like mine. Cast. Older ones are plastic. Newer ones are cast.


I just did this 2 months ago. I have some tips if you would like. Just shoot me a PM and I'll send you my cell number.

If you would do a write-up with photos and socket sizes that would be a great addition to the board.
 
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Found my notes!



Impeller kit = 862232A 2 $28.15/each @ JMS online. I carry a spare onboard + the tools needed to change.

Impeller change x 2 – took me 5 hours total including some swearing and breaks to stretch when the back got soar. If you are small this will be a lot easier. I'm 6'2" and about 246 lbs.

I removed the cockpit table holder first.

To get the hoses off and on the back of the water pump I am laying on the bottom of the engine compartment. If I can fit you can too. You need to overcome the idea that you can’t get down that far.

It would really help a lot if you have someone to hand you tools. I didn’t.


Remove the serpentine belt.

To remove the water pump I used a deep 9/16” socket, removed one bolt and one nut just above and to the right of the water pump, remove the bracket that goes to the alternator then remove the one hose that goes below the water pump from the top of the hose. This hose I only took off from the top. This hose does not go to the ware pump, its just in the way.

Remove two hose clamps on the water pump then pull the water pump off and out. Turn and pull the hose one at a time. They are hard to get off.

Open the water pump. Note the fin orientation. Take a photo with your phone.

To remove the impeller I used needle nose pliers holing the top of the water pump with my feet.

To get the new impeller in I put ty-raps around the impeller and got the fins all in the correct position then covered the impeller and inner pump housing with KY jelly.

Replace O-ring then close the pump.

To get the hoses back on the port water pump I put the pump on the threaded rod sticking out, put the nut on then pushed the hose onto the water pump, top red hose first then the back one on the bottom. Tighten hose clamps.

Once the hoses are on, remove this one bolt, put alternator bracket back on, reinstall the nuts and bolts, hose and serpentine belt.
 
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The plastic ones tend to wear out over time. You might get 1 impeller change - before the plastic housing is shot. If cast - they should last significantly longer. Sand tends to wear grooves into the pumps. A dock neighbor ignored the groves and the new impeller trashed the plastic housing within 10 hours and he was taking on water. So, good luck with your impeller change.
 
skolbe said:
The plastic ones tend to wear out over time. You might get 1 impeller change - before the plastic housing is shot. If cast - they should last significantly longer. Sand tends to wear grooves into the pumps. A dock neighbor ignored the groves and the new impeller trashed the plastic housing within 10 hours and he was taking on water. So, good luck with your impeller change.
Click to expand...

Sand wears groves in the cast pumps also.

Stupid engineer was too stupid to engineer in a stupid wear plate.

Did I mention that this is stupid?
 
Dale,

I just replaced my impeller back in the spring. My mechanic said I would likely have to replace the entire unit next time which would probably be prior to 2012 season. I had approximately 285 hours on the boat during that time.
 
Presentation said:
Sand wears groves in the cast pumps also.

Stupid engineer was too stupid to engineer in a stupid wear plate.

Did I mention that this is stupid?
Click to expand...

Yeah, you did. And for good reason, too!:smt001 The only way around this is to be proactive and replace the impeller on a (more) regular basis, especially if you are boating in shallow, sandy water.

I've thought about using this (it's rebuildable) when the time arrives to replace my pump, but don't have any personal experience to comment one way or the other. The only thing I can say is that ITT (Jabsco) has been around for a while and I've only ever heard good things about this pump.

http://www.ittflowcontrol.com/marin.../43210-0001-43210-bracket-mount-1-14-pump.htm
 
Wow! Great information in the post folks! I had no idea there were so many bored boaters out there as I hoping to get back in the water soon!

I'm not sure if my pumps are truly cast or not. I didn't spend enough time when looking at them to determine if they are or not. I'm 6'4" so I really wasn't in the mood at the time (closing down the boat) to lay down there and try to figure out what I had to deal with.

I guess the short answer is either way if you need to replace cast or plastic as a result of the grooving, you need to replace the entire pump, right?
 
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Oh, and another one - do the impellers need to be changed with the boat out of the water? I've read that the boat will take on water which sort of makes sense. Just wanted to know if there was a trick to it that would prevent you from having to pull the boat if it is in the water. Mine is out now and I plan on doing it out of the water but just in case something goes bad while in the water, I'd like a contingency and be prepared in knowing what I'm dealing with!
 
DaleM said:
Oh, and another one - do the impellers need to be changed with the boat out of the water? I've read that the boat will take on water which sort of makes sense. Just wanted to know if there was a trick to it that would prevent you from having to pull the boat if it is in the water. Mine is out now and I plan on doing it out of the water but just in case something goes bad while in the water, I'd like a contingency and be prepared in knowing what I'm dealing with!
Click to expand...

First time, yes, do it on land. Even on land you will get wet.

As soon as you pull the hose off the water pump the 3 gallons of water inside the engine block will run out the hose.

To change the impeller in the water your steps are the same except:
#1) Test your bilge pumps first.
#2) make sure your batteries are fully charged.
#3) As soon as you pull the hose off the water pump, stuff a rag in the hose and flip the hose up. Even doing this you will get a good 10 gallons of water in the bilge.
#4) When you go to put the hoses back on work fast. Expect to spill another 40 gallons of water. Expect to get wet.

My ‘big idea’ that is untried, is to put a hose on my muffs, so I don’t lose the muffs, dive down and put the muffs on the drive over the holes before I start the impeller change process. Again, I’ve never tried it, but once I get the chance I will go for it and report back.
 
My first time - I had the boat sitting on a hydrohoist lift - just a bit out of the water - so it wouldn't siphon -
 
I ended up needing a new housing this summer. I had my impellers replaced the year before and this year in the middle of summer i was heading out to our favorite shallow area and I dropped a belt on the starboard engine. I limped back to the slip on one motor, the one without power steering and when i got back i picked up another belt and put it on. I bumped the engine over and the belt came off again. I looked at the pulley on the pump and it was not lining up with the rest. I could grab the pulley and shaft and slide it in and out a good 1/4 inch. The sand had worn the pump housing to allow the shaft to slide in and out.
 
I thought I'd post some pictures of the SW pump impeller change. It was tough as Presentation mentioned getting around down there and it made taking pictures tough too.

In short the steps described in this thread were spot on. Remove the idler shive bracket that goes to the alternator and the block which mounts behind the pump bracket.

One thing - there are washers behind the bolts that need to get between the block and the bracket. I had one fall down into the bildge because I didn't know its was there. Just keep an eye out for it.

Here's a shot showing sorta where the bolts are.
IMG_1388.jpg




Here's a pic showing the one hose that got pulled from the top only in attempt to get more room to work behind the pump.

IMG_1391.jpg



Here's a rear view of the pump:

IMG_1389.jpg


And finally the pump after you remove about 6 or so bolts to split the case:

IMG_1393.jpg




One more FYI:
The oring that comes with the impeller kit is completely round. I initially thought I got the wrong oring because I thought it would be more to the shape of the housing. After comparing the old one to the new on, it's the right one. They just come round stock and over being in the pump they end up somewhat holding their shape.
 
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