Hardin Marine stainless steel replacement for Merc seawater pump

Dream_Inn

I change mine in the spring (no sense changing in fall and letting it set all winter) & then I will go thru two full summers.  So, basically, every 2 years.  Skuter, I'd say change it.  Not worth the risk waiting.  Just wait until spring, but do not start up motors before changing.  That is where it is mostly likely to fail, first start in the spring.

louscag

I have the Hardin pumps they last me around 50 hours. They have warrantied me 3 pumps but still a pain to be getting a little over a season. I have 496 fresh water cooled in New Jersey waters. The last replacement is a new design not out yet its a Gen 7 plus I will put on in the spring it has a larger bearing and seal

Glassguy54

There is a raw water pump conversion kit from a company that eliminates the horrible mercruiser design and makes it more like the the Volvo Penta design, which is mounted on the crank pulley and takes maybe 5 minutes to switch out the impellor. I can't understand why Mercury designed such a Byzantine raw water pump system when it would be SO EASY to make it more user friendly. WTF???!!! Johnson Raw Water Pump, around $200.00.

aero3113

@louscag , it’s nice to see they have an upgraded pump. I will request them when I order mine.

@Glassguy54 , interesting.

Black_Diamond

Interesting. I will have to look at mine for that ‘plus’ logo. 

Going over size on bearings vs proper sizing usually indicates an application issue. Belt over tensioning. Belt misalignment. Pulley runout
(squareness to shaft). Improper bearing installation can be an issue too. 

Depending how much you use your boat, false brinelling can cause bearing failures too. 

All or any of the above will cause problems. The bearings should have an L-10 life of 10’s of thousands of hours....at a bare minimum. Think of your alternator bearings running at near 10,000 rpms and they rarely fail. 

LaRea

louscag said:

... The last replacement is a new design not out yet its a Gen 7 plus I will put on in the spring it has a larger bearing and seal

@louscag thanks for posting that.  I had heard they might modify the design.  Good to know the new version is out.  

reneechris14

Bought mine last spring march 2019 and no plus on mine

rasbury

I still don't get all the fuss with these pumps. They are sharp looking. What fails on the pump?  Bearing should last forever and it is not smart enough to know if it is sitting in brass or stainless. Impeller gets a set to it and no longer seals? Same comment. Nest problem which has been my experience is the face of the impeller gets sand between it and the housing, wears groves and loses it's suction...so I bought the kit that has the SS "washers" and a shorter impeller. I have replaced once so have averaged a little over 100 hours in each and replacement was really just for the impeller and changed the plates out. 100 bucks. Not feeling the need to spend the 8 or 900 bucks they cost...

LaRea

On Hardin pumps, the pump shaft has sealed bearings.  The problem is that the seal fails, allowing water into the bearing race.  Once that happens, it's just a matter of time before the bearings fail.  

I don't have a clue why the bearing seal fails, but I've had four failures in six years.  

aero3113

@rasbury , the big selling feature of the Hardin pumps to me are the two replaceable wear plates. Now that it looks like they’re upgrading the bearings, it seems like a no brainer to upgrade to them if you have to replace your original pumps.

rasbury

So I have replaceable wear place in my Merc pump for a hundred bucks and not spending seven or eight hundred dollars to get a stainless steel housing to replace wear plates. if you're having issues with bearings then you probably have something else going on as others have mentioned like alignment or belt tension.

aero3113

My bearings are starting to leak because they’re  over 10 years old. Belts are tensioned correctly and no alignment issues. OEM pump costs about the same as a Hardin pump. @rasbury, do you have inner and outer wear plates in your pump?

rasbury

Yes I do. My pump is a 2006 vintage but only has about 300 hours on it. How many hours were on the pump? My coolant circulating pump has had no issue so far.....wish I hand not said that!

aero3113

About 450 on the raw water pump housings, no weeping on the circulating pumps yet...

rasbury

are you closed cooling??

aero3113

Not closed cooling, I've thought about putting kits on.

rasbury

that was a must for me.....most (99%) I'm in fresh but so many boats down here come from salt(99%) at least in this style and size...plus I wanted to go in salt when I can find the dang time....I'm really glad I did when I replaced my spacers - my manifolds will last forever!

Dream_Inn

While I'm not disagreeing with you Ras, the cost of the Hardin pumps that I bought were not 6 or 700 bucks, they were half that.  I have not had to replace mine as LaRea has been stating.  I've gone thru 3 summers with it, and even the wear plates look just fine.  So, I'm happy and as I said I replaced the other OEM one last summer (it had only last 4 seasons and was brand new and much more expensive than the Hardin I bought last summer).  I do wonder if something is not set up correctly with @LaRea 's ??

LaRea

@Dream_Inn - it's definitely not just me.  Last year I discussed my boat's issues with Hardin.  They acknowledged that a lot of customers were reporting bearing failures after a couple hundred hours.  At that time, they were working on redesigning the pump body to allow room for bigger, beefier bearings.  Now the new version is entering production.  

If you look on Hardin's web site, the original Gen 7 pump only has one product review, and it says the bearings failed after three seasons.  

(No mention of the Gen 7 Plus pump yet ...)

davidbrooks

I was thinking that one of the biggest reasons for bearing failure would be if the belt was too tight.  I know i am guilty of that sometimes.  Mine have been on for one two seasons. The other thing is that the rubber impeller itself is larger.  Really everything is just built a little bigger and stronger.  Plus...who doesn't want more chrome on their engines.

aero3113

I ordered the Hardin pumps today. I called in and specifically asked for the upgraded pumps (Gen 7 Plus) to be shipped. If anyone is interested, the new part number is 625-4131 .

aero3113

Since I have the new pumps coming, I started to remove and prep the rear housings. Some definite scoring on the old wear plates. Do you leave this plate in place when the new plate gets installed or remove it? The impellers itself look ok, not sure when they were last replaced. Also, you can see definite evidence that the bearings were leaking.

Port

Starboard

aero3113

Both port and starboard impellers were actually getting ready to strip out on the shaft. Port isn’t as bad as starboard, they both have excessive play where you can rotate the pulley back and forth.

LaRea

Oh yeah, it was definitely time. 

The Hardin pump has wear plates on both sides, so don't worry about that scoring.  

reneechris14

Yup that seal has been leaking for while must of had evidence on the floor under the pump. The new also has a gasket to go behind the wear plate. Probably made it easier to get out with the fuel cell  out. Remember the Hardin pump uses a different impeller.

aero3113

reneechris14 said:

Yup that seal has been leaking for while must of had evidence on the floor under the pump. The new also has a gasket to go behind the wear plate. Probably made it easier to get out with the fuel cell  out. Remember the Hardin pump uses a different impeller.

Fuel cell out? I didn’t remove anything in front of the engines. I have about 2 feet of open area in front of the engines.

reneechris14

The cool fuel module hits the little notch on side of the pump when pulling it forward off the stud. Yours maybe a tad different then the horizon model. I should of said fuel module in stead of cell.

aero3113

LoL, got ya. Port side module is out, I didn’t have to modify the starboard side. I actually pulled the pump before the module came out. It will definitely make it easier going back in.

aero3113

One thing that helped me also is that the stud backed out on both sides.

aero3113

I received the Gen 7 “Plus” pumps today! I was surprised to see that they have weep holes. Did the earlier version have the weep holes? I don’t remember them on the OEM pumps. Hopefully I can get them installed in the next week or so. I couldn’t find any Permitex #3 in the 3 stores I went to, I had to order it.