Sea water pump - longevity?

mattie

Ours let go Sunday night. Pump shaft & pulley worked its way fwd. Threw the serpentine belt off. Immediate overheat, no power steering, etc. Belt demoed some other stuff.

Fourtunately only 1000ft from our dock. Got towed in.

I'm 3/4's handy, but there was no being prepared for that mech failure. Bit of a gong show.......

should be be good to go for Friday. Not sure if there is an expected lifespan for sea water pumps.

mattie

LaRea

Most pumps last 10 years or longer, but I've never heard of one failing that way. 

craigswardmtb

It's usually a seal that goes in the shaft or its just so scored you cant get a prime on it. I replaced one pump this season with the SS Hardin pump (seal failure) and stainless plates on the other (scored housing).  12 year old boat. 

Dream_Inn

I replaced one of mine last year and the other this past spring.  One due to scored housing, the other due to shaft leak.  10 years is about right.  I'm hoping the Hardin pump will last longer.

reneechris14

Don't forget the idler above the pump is next if it got wet.

craigswardmtb

reneechris14 said:

Don't forget the idler above the pump is next if it got wet.

I found that out the hard way.  The bearing literally disintegrated at 27knts, 7 miles from an island and 25 from the mainland.  That's the nice thing about having a second engine, albeit it was a slow bumpy cruise to the anchorage.  Whats the saying, "two is one, and one is none".

Willhound

Mine was changed out (rebuild kit) this year after 17 years. The phenolic (plastic) housing was cracked and leaking. Changed thermostat while we were at it. I plan on changing the idler and serpentine belt next week before an upcoming trip.

wm61356

Prior to launch this year, I replaced my port pump (OEM Brass) due to scoring of the housing. I went with the stainless steel version from Hardin Marine. Last week the starboard OEM Mercruiser pump failed exactly as described by @mattie at the beginning of this post. I replaced it with a pump from Hardin Marine as well. In talking with my Mercruiser mechanic, I learned that they have experienced many instances where the Merc pump fails and the shaft and pulley "exits the front of the pump". The mechanic wasn't surprised to hear of this type of failure, stating that it fairly common.

mattie

wm61356 said:

Prior to launch this year, I replaced my port pump (OEM Brass) due to scoring of the housing. I went with the stainless steel version from Hardin Marine. Last week the starboard OEM Mercruiser pump failed exactly as described by @mattie at the beginning of this post. I replaced it with a pump from Hardin Marine as well. In talking with my Mercruiser mechanic, I learned that they have experienced many instances where the Merc pump fails and the shaft and pulley "exits the front of the pump". The mechanic wasn't surprised to hear of this type of failure, stating that it fairly common.

Marine mechanic said the same thing. He has seen more & more factory pumps failing this way. I'm pretty anal with my stuff. This is one of those items that you can't possibly predict. 

Thank goodness the failure was close to home. Pretty much only bathing suits & BudLight on board. I had no possible way of limping home. Tow was the only option.

They are replacing with factory OEM stuff. I looked at the Hardin, but I would imagine we will upgrade the boat in the next 2-3 yrs. Factory parts should suffice.

mattie

I found that out the hard way.  The bearing literally disintegrated at 27knts, 7 miles from an island and 25 from the mainland.  That's the nice thing about having a second engine, albeit it was a slow bumpy cruise to the anchorage.  Whats the saying, "two is one, and one is none".

With a bowrider dayboat - we only use the boat in good/sunny/swim days. Rarely stray too far from home port.

I've often thought about the saying above..........it's absolutely correct.

Black_Diamond

That bearing was likely screaming, you just could not hear it before it let go.

I had 13 years on my OEM pumps, replaced both with Hardin Marine SS pumps.  The old ones were scored up, still working but were do.

kordo

Gentlemen, I read a few comments about getting 10 years from oem raw water pumps.  Seems pretty good but can you translate that into hours?  Someone who runs 100 hrs a year probably won't get 10 years.  Thank you.

MarkB

kordo said:

Gentlemen, I read a few comments about getting 10 years from oem raw water pumps.  Seems pretty good but can you translate that into hours?  Someone who runs 100 hrs a year probably won't get 10 years.  Thank you.

A good question. I was told it should last 3 years ... and that was given running 50 to 100 hours per year.  But I'm not sure if time also makes the impeller brittle ... so even if you don't run it??

Liberty44140

Mine is at 13 years and 300 hours. This winter I plan to either replace it, or do the rebuild kit with new wear plates. We will see....

MarkB

Liberty44140 said:

Mine is at 13 years and 300 hours. This winter I plan to either replace it, or do the rebuild kit with new wear plates. We will see....

By the way, the recommendation to replace it in 2 to 3 years is preventative maintenance. If may last 5 years, but I think someone has looked at the stats and determined the failure frequency starts increasing dramatically after 3 years.  For such a cheap part, no point in taking the risk.

LaRea

@kordo you're talking about the pump body, not the impeller?   

The life of the pump body depends entirely on how it's treated.  If the only thing it ever pumps is clean fresh water with no debris, it could easily last 1000 hours or maybe much longer.  If you run the motor with the intake sitting in sand, you could probably destroy a pump body in a few minutes.  

reneechris14

I must agree with @LaRea my pumps had 380 hours body was still pretty good the front seal was leaking. Probably could of did a rebuild but just went with the Hardin pump 900 bucks for 2. Life is short don't get over heated. Get it get it lol

randy56

I bought a fishing boat last year 1995, from original owner, that the impeller never had been changed in 23 years. It was a 75 hp Merc. A fishing boat gets used about 25 hours per year on average so it had about 575 hours on it.  To keep from getting over heated I changed it. But it looked fine. 
I think most boaters that use there boat 75/100 hours per year change them every 3 for peace of mind. 

zaverin1

I don’t get Hardin pump trend at all?
why not going with the plastic housing and replace impeller every 2-3 seasons depending on use and conditions?
old applications used metal case pumps and now the trend is back again. I hear you can get 1 gal better per hour lol? That’s nothing.

Liberty44140

MarkB said:

Liberty44140 said:

Mine is at 13 years and 300 hours. This winter I plan to either replace it, or do the rebuild kit with new wear plates. We will see....

By the way, the recommendation to replace it in 2 to 3 years is preventative maintenance. If may last 5 years, but I think someone has looked at the stats and determined the failure frequency starts increasing dramatically after 3 years.  For such a cheap part, no point in taking the risk.

Thanks for the feedback mark but the oem pump replacement for me is $900 (cost of two Hardin full pump assemblies). I don’t consider that cheap maintenance but hey that’s just my budget. If you are really replacing the pump on your Merc every 3 years, can I have your old one? 

Liberty44140

Would love to convert my merc pumps to Johnson’s with easy impeller change like Volvo. I know it’s possible but it doesn’t look simple. 

69fastback

I replaced mine do to scoring just this year, at slightly under 400 hours. 

Dream_Inn

I think maybe a couple people got the question confused with replacing the impeller, not the actual pump.  I replaced one of my pumps 4 years ago and the other 2 years ago.  So, not too bad for originals from 2008.

Dude_Himself

@Alswagg Pics or part numbers?

Liberty44140

Yea I’d be interested in how to do that. My 342 is an 06 so I’ve got more room in front of the engines