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Sea water pump question

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07Crownline

New member
Tried to upload a couple photos, will be very difficult to explain if they didn't upload. I have a bravo 3 5.7 and I just got the boat not long ago, so for maintenance I thought I would change the impeller. Once apart, I have 2 steel spacer plates attatched to the rear housing, it appears for proper clearance. The plate that lays on the brass housing has a place for the impeller to ride, and the other one is cut out so the impeller doesn't ride on that plate, it appears to be only for clearance. I'm confused because I can't find any information on this setup. Makes me wonder if at one time they ground down the brass and made this up as a repair, but I honestly don't know. I know I ordered a new plastic housing with a wear plate and to be honest I have 1/8 inch between the front housing and the plastic housing before I even start tightening the bolts. This is not a part I want to fail on the water. Thanks for any advice you can provide.
 
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If I am reading this correctly, you have the 3 piece pump there. The new style is a one-piece body. This has only a single end plate and bolts up to the pump shaft housing. Strongly urge that you get this kit instead of the old style.
 
I would have to say you are correct. I will research and see what I can find. It's aggravating that the parts breakdowns don't show this. Also, I'm not a huge fan of having a piece of plastic below the water line that could break and flood the boat. It would be awesome if I could just replace the steel parts as needed and keep the housing.
 
When you tire of the belt driven seawater pump issuess, and if you have enough space/distance in front of the harmonic balancer, consider replacing that pump with a Johnson F5B-9 or F6B-9 crankshaft style pump.

No more belt tension side load (that wears against the shaft bearings), no more expensive Merc repair parts, and very easy impeller access for replacement.

Crankshaft pump 5.jpg

Crankshaft pump 4.jpg



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Both of these responses are ludicrous. Mounting a crankshaft driven pump means rerouting belts, plumbing and will take more time and money than it's worth over just putting a new pump kit on what he has. The side load on the bearings is well within their tolerance and has little to do with longevity; they're made to run this way. Adding to that will be what to do about a lift pump.

Just silly.
 
Now lets straighten this out.

Forget about a different pump.

Your pump, if OEM, has a back cover with a possible wear plate that is replaceable along with another wear plate that fits into the actual pump housing which is also replaceable.

Post a picture of your pump so I can see what you have
 
Because of the difficult location of my sea water pump I chose to change over to the Johnson Crank mounted pump. I also installed a through hull sea water pick up and elimininated the Bravo 3 leg pick up. As Rick said, you do need room in the front of your motor about 5.5 inches. Best upgrade I've done in a long time, plenty of water now.
Rick
 
o2batsea said:
Both of these responses are ludicrous. Mounting a crankshaft driven pump means rerouting belts, plumbing and will take more time and money than it's worth over just putting a new pump kit on what he has. The side load on the bearings is well within their tolerance and has little to do with longevity; they're made to run this way. Adding to that will be what to do about a lift pump.

Just silly.
Click to expand...
You may think that it's ludicrous and silly until you've had enough of the belt driven seawater pump issues and want an alternative!
Keep in mind that you do this once only (i.e., spending the time re-routing belts, re-configuring hoses, etc.) and you don't need to look back.


rick3452 said:
Because of the difficult location of my sea water pump I chose to change over to the Johnson Crank mounted pump. I also installed a through hull sea water pick up and eliminated the Bravo 3 leg pick up. As Rick said, you do need room in the front of your motor about 5.5 inches. Best upgrade I've done in a long time, plenty of water now.
Rick
Click to expand...

Rick, good for you.
I've done this conversion a dozen or more times, and I've walked many owners through the procedure.
Even the Chrysler boys (ME dot com Chrysler forum) are beginning to do the conversion. One member has designed an adapter.

Average Joe is intimidated by his belt driven pump and impeller access. He looks at this and says "oh man.... this looks difficult..... this can wait".
So now average Joe has deferred his maintenance. Once Joe does tackle the job, now he's looking at the parts cost to replace certain items, etc.

The crankshaft pump does not pose the same issues, and is much less likely to intimidate average Joe!


If we think that the crankshaft pump idea is ludicrous and silly, then I guess we should inform Indmar, PCM, Crusader, Volvo Penta and a few more companies, and persuade them to go back to belt driven seawater pumps! ;)


If you are happy with your OEM belt driven seawater pump.... then stick with it.
If you would like an alternative, then give the Johnson crankshaft pump consideration.


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I've had all(?) three water pump location on my boats over the many years I've owned and personally maintained boats. If I had the room in my present boat, I change over to engine driven. I'm not amused by having to do a face plant on my deck to get to my raw water pump.
 
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If we think that the crankshaft pump idea is ludicrous and silly, then I guess we should inform Indmar, PCM, Crusader, Volvo Penta and a few more companies, and persuade them to go back to belt driven seawater pumps! ;)
Click to expand...
Nope not silly or ludicrous but paying a thousand bucks or so to reroute all the stuff that needs rerouting just so you don't have to reach under the manifold is silly and ludicrous. Please read posts carefully and contextualize what I write in terms that are relevant and avoid Trumpian word twisting.
I'm sure that selling these conversions to weekenders is a profitable pursuit, but for us regular folk that turn our own spanners it's a no. You're asking me to give up a significant amount of fuel and beer.
 
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F 6 for sure, I keep a spare one on the boat just in case.... I could probably b
change the complete pump in 30 min. Pump was $125 approximately
 
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o2batsea said:
Nope not silly or ludicrous but paying a thousand bucks or so ...........
$160/$180 for a F5B-9.
shorten and/or re-route the belt .......$XX
new supply hose..... $XX
new suction hose.... $xx
If these add up to $1,000, something is wrong with your purchasing power.


....... to reroute all the stuff that needs rerouting just so you don't have to reach under the manifold is silly and ludicrous.
I generalized when I used the term "tired of the belt driven seawater pump issues".
The issues could be:
.... as you described....... "don't have to reach down under the exhaust manifold".
.....the expense of the Merc pump repair parts.
.... the expense of a complete replacement Merc pump.
.... the not so easy task of impeller R&R.

Again...... keep in mind that you do this conversion once only (i.e., spending the time re-routing belts, re-configuring hoses, etc.) and you are done!

*** Please read posts carefully and contextualize what I write in terms that are relevant and avoid Trumpian word twisting.
I did read your post carefully, and I did NOT twist your words.
It was clear that you do not like the idea of the crankshaft pump conversion, and that you did not mention any issues with the Merc pump!
This is an option (not a mandate) for those who may be tired of the belt driven seawater pump issues.
Not all people will be skilled enough and/or be willing to make the conversion.

I'm sure that selling these conversions to weekenders is a profitable pursuit,
By the way..... I do not sell these conversion kits.

but for us regular folk that turn our own spanners it's a no.
This conversion is a very user friendly one.
It can be done by most any boat owner who does their own work..... I.E., DIYr, weekender, etc.

You're asking me to give up a significant amount of fuel and beer.
Nope..... I didn't ask you to give up anything!
Perhaps see *** above, and read post #5 again.


Lastly, let's not argue over this...... there is enough bantering, bashing and arguing on this forum as it is.
Let's keep it civil, and let's understand that we make suggestions ONLY.
Each member is free to do as they please.

Click to expand...

rick3452 said:
F 6 for sure, I keep a spare one on the boat just in case.... I could probably b
change the complete pump in 30 min. Pump was $125 approximately
Click to expand...

Occasionally, we can find a new F5B-9 on sale for around $160 to $180.
The F6B-9 costs a bit more.





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It was clear that you do not like the idea of the crankshaft pump conversion, and that you did not mention any issues with the Merc pump!
This is an option (not a mandate) for those who may be tired of the belt driven seawater pump issues.
Not all people will be skilled enough and/or be willing to make the conversion.
Click to expand...
No, I wrote that the idea of changing a perfectly good pump to a different location simply to avoid bending knees is ridiculous. You seem to miss this distinction. I personally have no care whatsoever where, what and how one chooses to have their water delivered. It's all good.

You fail to mention the fuel lift pump. If one deletes the Mercruiser pump then you have no fuel pump. You can't bolt one to the regular fuel pump mounting on the block cz there's no fuel pump lobe on the camshaft. So your only choice is an electric one. Now you have to redo all the fuel plumbing, wire up the new fuel pump, fuse it, blah blah.
You could, I guess, leave the existing fuel pump where it is but then you still have this housing with its associated shaft, pulley and belt to maintain. So what's the benefit there except, of course, now your water pump is in front so you don't have to bend over your beer gut to service the pump anymore.

Again, thanks for suggesting relocating the pump but it's really an expensive and somewhat frivolous thing. OK so you may be old and have limited mobility, that's fair. Certainly this population cohort needs things made as easy as possible and this conversion works for them. I don't need it yet. I keep fit and am not overweight or flabby. Even though I have been in major vehicle wrecks and my 60 year old bod ain't what it used to be I can still move around and get out of my own way.

$160/$180 for a F5B-9.
shorten and/or re-route the belt .......$XX
new supply hose..... $XX
new suction hose.... $xx
If these add up to $1,000, something is wrong with your purchasing power.
Click to expand...

Oh please. You and I both know that these aren't the only costs and if you put in a seacock, strainer and have to buy an electric fuel pump and the stuff needed for that then yeh you're into a full G or more. Maybe you save by using the cheapest stuff you can find or even buy used. You don't count labor so you assume that everyone reading this has the chops to do this themselves. OK, if they do, and their "free time" is worth anything to them, then they are going to blow a day on this. I dunno about you but I have to account for what my free time is worth to me and I round it up to $100/hr. If something's going to take 4 hours thats $400 I calculate into the job estimation. If you aren't doing that for yourself then you are not only cheating yourself but being foolish. Free time ain't free, you earn it.
So, sure go ahead. Do this thing Rick says. Be happy, enjoy life. Go boating. Break stuff.
 
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o2batsea said:
No, I wrote that the idea of changing a perfectly good pump to a different location simply to avoid bending knees is ridiculous.
I don't recall mentioning or suggesting that we change out a perfectly good Merc pump.
My suggestion was intended for those who were tired of the routine Merc belt driven seawater pump issues and the high cost of replacement parts.
Here it is again:
When you tire of the belt driven seawater pump issues, and if you have enough space/distance in front of the harmonic balancer, consider replacing that pump with a Johnson F5B-9 or F6B-9 crankshaft style pump.
Click to expand...
You fail to mention the fuel lift pump.
Correct.... I made no mention of it, and you made no mention of it in post#2.
Does the OP have that combo pump????

If one deletes the Mercruiser pump then you have no fuel pump. You can't bolt one to the regular fuel pump mounting on the block cz there's no fuel pump lobe on the camshaft.
That is correct.

If I may ask..... what's your take on that Merc fuel pump/seawater pump combo unit? I think that it's a poor design.

So your only choice is an electric one.
In all fairness, keep in mind that not all who would be doing this conversion would have the fuel pump/seawater pump combo unit.
Again..... does the OP have that combo pump?

Now you have to redo all the fuel plumbing, wire up the new fuel pump, fuse it, blah blah.
See above.... and even if so, it's a One Time ordeal!


Oh please. You and I both know that these aren't the only costs and if you put in a seacock, strainer
No one said that you had to install a thru-hull pick-up and the other components.
The amount of suction and supply force between the Merc belt driven pump and the crankshaft pump are very similar. Minus the new location for the crankshaft pump, you can use the Merc seawater path.
Click to expand...
 
I knew you couldn't resist getting the final word. So predictable that you feel you have to be right about ev-er-y-thing, and creepy.
 
o2batsea said:
I knew you couldn't resist getting the final word. So predictable that you feel you have to be right about ev-er-y-thing, and creepy.
Click to expand...

Wow..... Catch 22.
If I respond to your post, I'm getting the final word in.... and if you respond to my post, you'll be getting the final word in.
It looks as though we've both been doing the same thing!
And while on that topic...... one way or another, there will be someone who gets the final word in (unless we go with the "Gone with the Wind" version).

Try to think of this as though it's not a contest, nor is it about right or wrong. It's about the importance of putting the complete info out there for the OP and/or for anyone else who may be interested in making this change.


Clarification and Disclaimer:

The idea is a suggestion ONLY, and it requires some thinking Out-Side-of-the-Box. No one is being forced to make this conversion to the crankshaft pump.
If you are completely satisfied with your Merc belt driven seawater pump, enjoy it!
If not..... I suggest giving some consideration to the conversion!




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"""""
You fail to mention the fuel lift pump.
Correct.... I made no mention of it, and you made no mention of it in post#2.
Does the OP have that combo pump????


Why would he make mention of it? Because you DONT know the product? As you only respond in generalities?



If one deletes the Mercruiser pump then you have no fuel pump. You can't bolt one to the regular fuel pump mounting on the block cz there's no fuel pump lobe on the camshaft.
That is correct.

Thanks for the Reassurance like we need your agreement!

If I may ask..... what's your take on that Merc fuel pump/seawater pump combo unit? I think that it's a poor design.

Poor or not, it is factory OEM. Worked when new and if any service bulletins exist to improve the "design" then so be it.

So your only choice is an electric one.
In all fairness, keep in mind that not all who would be doing this conversion would have the fuel pump/seawater pump combo unit.
Again..... does the OP have that combo pump?

Again, you make assumptions based on lack of product knowledge continually! You dive in because you feel you have the only and correct answer on products you have no experience supporting

Now you have to redo all the fuel plumbing, wire up the new fuel pump, fuse it, blah blah.
See above.... and even if so, it's a One Time ordeal!""""

One time or not this is not our/your choice to make and is not a choice to be offered. Fix/replace with OEM and simply be done with it. No need to reinvent the wheel every time a water pump/impeller issue arises based on YOUR opinion. Answer his question on OEM REPAIR/REPLACE ONLY. Suggesting a completely different system without understanding the full scope of the project does not belong here!
 
I do want to make mention that when I changed over to the Jonson crank pump I did not have deal with fuel pump issues. Also when I explained to the mechanic that was changing out my 5.0 to a new 5.7. He Strongly disagreed with me wanting the Johnson... until he saw the placement of my motor and the area around it.
 
rick3452 said:
I do want to make mention that when I changed over to the Jonson crank pump I did not have deal with fuel pump issues. Also when I explained to the mechanic that was changing out my 5.0 to a new 5.7. He Strongly disagreed with me wanting the Johnson... until he saw the placement of my motor and the area around it.
Click to expand...

FYI, As a Paid Factory Certified Mercruiser/Mercury Tech I cannot suggest that you modify your OEM set up as that would now make me the manufacturer and responsible for and detrimental damage caused by the custom install.
 
All I will say is that Mercruiser developed this combo pump unit for good reason. I'm sure they tested front mount pumps, engine mount pumps, remote pumps, whatever pumps and determined that this design was the direction they wanted to go. Much time and even more money was put into this little combo pump. They are in use on bazillions of vessels and have undergone countless more bazillions of hours of use. I absolutely dismiss anyone who says this is a poor design as clearly, it's not. If it was, then people would be complaining loudly about it. I hear crickets.
As I said if you have to stretch the seam of your trousers to service it, that's not a design flaw, just your own physical issues. If the engine bay is so tight you can't get your hands in there then shame on you for buying a boat with a poorly designed engine bay.
 
Perhaps some of you are having trouble understanding that the idea of the conversion to a crankshaft pump was a suggestion ONLY, and it was being suggested to those who may be tired of the Merc OEM seawater pump issues. Please also understand that the subject is not limited to the combo raw water/fuel pump (that o2batsea brought into the mix).

For those who believe that Mercruiser developed the OEM combo pump unit for good reason, consider that they may have designed this pump in order to have yet one more expensive proprietary part!

For anyone who is dismissing this combo pump as a poor design, try doing a google search: "issues with Mercruiser combo fuel pump and raw water pump" (vary your key words so that you can find more of these articles).

These are just a few forum posts. You can find this same subject being discussed on other forums.
In fact, this topic has been discussed here on ME.com.
Sadler says;
The sealed/oiled side of the sea water pump (not the rubber impeller, that
was new, and still ok) on my '95 Mercruiser 454 Bravo III failed this past
weekend just north of Beaufort, SC with only 239 hours. Talking to several
dealers, this is not at all rare, especially if you don't change the oil in
the pump every season. Does this sound right? Does anyone really change this
oil every season? And how typical is a sea water pump failure? Is 239 hours
average? My new one cost $430, and that is parts only and doesn't include my
labor for changing it--not an easy job! Good news is that BoatUS unlimited
towing saved me a $1600 (50 mile) towing fee!! And should I expect lots of
things to be breaking/wearing out now on my Mercruiser with 239 hours ? That
translates into only approx. 6000 miles at an average speed of 25 mph.
That's hardly through the break-in period for a car!


Jerry says;
My manual says to check the oil every 50 hrs. of use and change yearly
using only Quicksilvers High Performance gear lube. To bad the drain hole
isn't low enough to drain all the oil though considering that there is only
about a 1/2 - 3/4 cup of oil.

Roy asks:
I have looked at our engine (not a particularly easy task ) and I could not
see any fill or drain plugs. Where on the water pump are they located?

Dave M posts:
Fourth issue, if oil gets diluted, then you are more likely to get wear of the arm and the cam. So you will start to get metal contamination of the oil. Again, it is only a small amount of oil, and there is no pumping and filtering to get rid of it. So it will try and settle to the bottom,where the shaft bearings are!

Fifth issue, if the oil gets diluted significantly with gas, it is more likely to leak by the bearing seals and get out, taking the oil with it.:

Click to expand...



For the DIYr who is removing this combo pump and changing the oil, it may be frustrating.
For the DIYr who has the seawater pump only...... R&R of the pump may still be frustrating.
For the non DIYrs who must use a shop, I'm curious as to what the average charge would be to R&R either style pump!









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As for the Fuel pump driver you are discussing, This is a great set up and have few failures. Although they are no longer being used, there are quite a few still in service.

The biggest problem is the Bravo Brass raw water pump, the shaft bearings go bad(possibly from belt tension), the newest version has wear plates.
 
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