Mercruiser Raw Water Pumps

i'm 65 , and wrenching and maintenance is what I do and have always done, and no stranger to this pump. Maybe the the captain can give his age, weight and height, that might give a clue to how this job is termed SIMPLE

58, 210, 6 foot.

Now please, go troll someone else. I'm not playing your little game.
 
I think this is the crux of the design. I guess I'm willing to accept that the rubber impeller is an unavoidable design choice based on a lot of constraints, but the real killer is that the pump itself isn't designed with any kind of ease of changing.

I haven't actually tried it, but removing the pump assembly appears to be necessary to gain access to the housing face where the impeller is actually located. I watched two videos, looked at some threads here, and my summary is that the task isn't exotic but is time consuming and troublesome.

If the impeller is a rapid wear item, then the pump design should reflect that and make the impeller easy to change.
You want your impeller to last a long time, stay out of the shallow water so you're not sucking up sand.

Really this job isn't that bad. Once you know how and do it a time or two no big deal. Truth....I mean would a stranger on the internet BS you:lol:, go for it, get 'er done.
 
You are the newbie here, although I'm not liked here as well, you have obliviously not done a water pump impeller job on a 310 da with a b3.
 
You want your impeller to last a long time, stay out of the shallow water so you're not sucking up sand.

Really this job isn't that bad. Once you know how and do it a time or two no big deal. Truth....I mean would a stranger on the internet BS you:lol:, go for it, get 'er done.

But would you call it simple ? When I think simple....many other things come to mind
 
i'm 65 , and wrenching maintenance is what I do and have always done, and no stranger to this pump. Maybe the the captain can give his age, weight and height

58, 210, 6 foot.

Now please, go troll someone else. I'm not playing your little game.
candlelight dinners, softly whispered poetry, and bare foot walks on the beach?:huh: You guys, I dunno....:smt043
 
I think everyone might have a different opinion on what "simple" means. What I might call simple for a certain job might be hard for someone else. And what someone else might call simple, I may find hard. We'd likely never totally agree on some of these things, simply because they are opinion based.
 
But would you call it simple ? When I think simple....many other things come to mind
Actually I find the hard part for me is the water lines. I'm older than you, with one knee that don't bend much some days, I'd still call it a simple job.

Clarification....I'd call it a simple job, but an awkward place to work in.
 
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When I saw the merc tech upside down on his head when getting the hoses on/off the outboard pump I knew i made the right decision to open the wallet. :smt001

I'm sure there's easier ways but he was conscious of costs and was able to remove the pump change them and back on in less than an hour each.

Fast forward 3 months later and a shaft seal then went on one of the pumps when on a trip. Courtesy of the serp belt, seawater was flung through the bilge including the flame arrestors of both motors - although no evidence of any ingestion when the arrestors were removed. Anyway called him back out again where he changed the seals, shaft and bearing assembly on both pumps for another $800.

Suffice to say I had questioned the merc tech whether he had done any crank mounted conversions - but no.
 
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I think the reason for the rubber is because it IS in a high wear place. If we placed a finer filter (to filter sand) in front of the impeller, I would imagine that it would also restrict water flow to the engine. So if a metal impeller was used, it may very well wear out just as fast as the rubber one, but yield a much higher replacement cost.

Interestingly, in addition to making an upgrade for the stock Mercruiser sea water pump, Hardin also make a high volume raw water filter for sand. I don't know more than what I read on their web site, but made with bypass valves so it can be literally filled with sand and still pass water in addition to being easily removable with a reusable, easy to clean filter.

Keep the fines out of your pump path as best as possible and you can make an impeller that doesn't need the properties of a garbage disposal.

I don't like shallow water, period. My previous boat was a jet a and had a working draft of about 15 inches with people in it, but the intake would clog with weeds which were a nuisance to clean out (and Yamahas have a clean out plug to make it easy), and I insist on swimming in 20-30 feet of water -- no beaches or sandbars for me.

So I figure if I'm running on new impellers and stay out of the shallows, I ought to avoid some of the wear and tear on the impellers.

I find the Hardin pump kits compelling, as are the Globe impellers which in theory are longer running.

I also like another suggestion in this thread of buying an additional pump and when replacing impellers, just replacing the entire pump assembly and rebuilding the reused one for the next engine and then rebuilding that one as the next "new" one for the next cycle. That makes less all-at-once work and putzing at the boat.
 
I had not been looking forward to replacing 4 oil coolers, especially the inboard ones. Coolers were 10 years old in saltwater. So when I lost an impeller I went to work. Installed crank mtd pumps and put the new coolers between the valve covers and carbs. Of course new water and oil lines in the lengths needed for the remodel. Now everything is accessible for everyday inspection and service as needed.
 
If the design is so great, why has the pump on the new 4.5 been relocated?

David, I don't think anyone is saying that it's a "great" design - or, at least, I am not. It's just "a" design and depending on a person's point of view determines their opinion of it. Of course, I'm also not saying that a crank-mounted setup isn't easier for maintenance - obviously it is. There's always room for improvement!

For what it's worth, Merc says the reason they use the existing setup is for space-saving and allowing their packages to fit into more boats.

The new 4.5L and 6.2L still have the pump in the same place as before. Nothing has changed there.

Mobo: That's interesting about the Hardin sand/filter thing you mentioned. I had not seen that before. I'll have to take a look at that - if for no other reason than to learn a little more about it.

FYI, traditionally "raw water filtering" has been a boat-manufacturer responsibility, not an engine manufacturer.
 
Mobo: That's interesting about the Hardin sand/filter thing you mentioned. I had not seen that before. I'll have to take a look at that - if for no other reason than to learn a little more about it.

FYI, traditionally "raw water filtering" has been a boat-manufacturer responsibility, not an engine manufacturer.

I'd guess impeller life is something of a function of the kind of water you suck in and what's in it -- the more hard stuff you suck in, the more wear on the impeller and impeller housing contact faces. If the boat is run in mostly clean, fresh water and running in shallows is avoided as much as possible, my guess is that the filter wouldn't be worth the expense and water line retrofit expense.

I'm in a fresh water lake that's pretty clear and I don't like the shallows like some people do. I see people on this lake on or real close to sand bars and I often wonder how they avoid simply grounding their drive units let alone not inhaling a ton of sand and silt getting in and out. My only real concern for my specific use is free-floating vegetation scraps which isn't uncommon but not pervasive and I'm guessing that the sea water intake on the base of the hull makes that less of a problem.

But if you were on a river, murkier water or spent a lot of time navigating shallows where sand or other bottom fines could be stirred up a good raw water filter setup seems like it would make sense. Even if its not directly a source of wear/damage to the impeller, it can't be good to pump gunk through cooling passages.
 
Another enemy of the rubber impeller is non use. If allowed to sit for prolonged periods of time the blades take a set, then when the engine is run this accelerates wear. It's been my experience that boats used often the impellers often show less wear than the occasional use.

And of course as others have previously stated, where the boat is used factors in to all this as well.
 
Hello to all who reads this and to you CaptRonn , my name is Frank , I'm no stranger to tools
or doing any type of repairs , new to boat engines repairs, down in the bilge its tight i'm short, 68 and fat so i have to squeeze in to places. I have to replace both these pumps
(sea water and fuel pump combos ) does someone in the CSR have pictures or Schematic on removal of these pumps or bolt location, or better where can I fine a free download of a repair manual showing this procedure . like I said i'm new to this site, also new to searching
on the web even searching on this forum. any help would be Greatly Appreciate
Thanks
 
At first I thought this was going to be about Mercruiser I/O pumps. Now there’s an inconsiderate design.

My current boat is my first inboard and I’m very fortunate in that it has a huge engine compartment, so impeller changes are a snap.

Despite being Merc 454s, I have Sherwood pumps that once lived on Crusaders. Having seen the stock pumps, I’m happy to have them.

Changing the impellers is a snap. Removing the pump can really suck.

Ease of maintenance was top priority for me when boat shopping last summer. Prior to that I worked an a boat with a 10’ beam and twins. Never again.

No more I/Os for me.
 
At first I thought this was going to be about Mercruiser I/O pumps. Now there’s an inconsiderate design.

My current boat is my first inboard and I’m very fortunate in that it has a huge engine compartment, so impeller changes are a snap.

Despite being Merc 454s, I have Sherwood pumps that once lived on Crusaders. Having seen the stock pumps, I’m happy to have them.

Changing the impellers is a snap. Removing the pump can really suck.

Ease of maintenance was top priority for me when boat shopping last summer. Prior to that I worked an a boat with a 10’ beam and twins. Never again.

No more I/Os for me.

Like you, I decided to make ease of self-service a priority when shopping for my current boat. The trade off was the lack of a mid-ship (or aft) cabin, but that was fine with me. Because of this, there is more room to perform maintenance in the ER and the engines are facing forward making the pumps more accessible. Even so, the job is not easy especially lining the two hoses back up to the fittings once the pump is loosely back in place.

With the wear issue on these brass pumps, I opted to go with "Aftermarket Marine" that utilizes two stainless wear plates on the ends and their "cut to fit" impeller along with an end cap/gasket in their kit. It's much less ($110) than a new Harding pump and the plates can be replaced if they become too scored. New impeller, O-ring, and gasket is only $35 for future. So far no issues with this product.
 
I did a brief search for these pumps you mentioned, but the site was chaos.

Very interested though.

Gotta link?
 

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