Raw water Pump
 

Installed the Hardin water pump 2 seasons ago and also replaced the intake hose from the transom.

To remove and replace of the pump is a real bear on my motor because there really is no room, so have to hang upside down for the most part. Installing the first round I removed the exhaust manifold which helped. The housing has some weight which only makes things worst. Removing the hoses from the pump was hardest part, and in part because of the new hose and weight didn't help. The increased difficulty has got me thinking about going back to the composite housing.

The Hardin pump has a small spot on one side which I think may not have been machined correct;y and noticed prior to original install. The spot did mark the impeller but not enough to cause any damage. Got the Hardin pump figure it would last longer and it does, but the inner wear plate is showing some grooves, not much. Figure I can get by with another install

Have till spring to decide if the Hardin goes back on or go back to the composite. Never had any issue with the composite

https://cimg5.ibsrv.net/gimg/www.off...a63ecf7e73.jpg
https://cimg0.ibsrv.net/gimg/www.off...7ad9fdbe79.jpg
https://cimg0.ibsrv.net/gimg/www.off...624b83b750.jpg
https://cimg6.ibsrv.net/gimg/www.off...be2b9c3eb5.jpg
https://cimg7.ibsrv.net/gimg/www.off...f79febec88.jpg

Does anyone make some kind of quick connect to male NPT fitting?

Installed the same pump a couple years ago. Thanks for the pic. The impeller came pre-installed in my pump so didn't get a look at the inside of the housing. Plan to replace the impeller this spring so I will see if I have the same issue as you pointed out here.

What kind of hose are you trying to remove from the pump? I use the parker EZ form hose from my transom to strainer which is very flexible and seems very easy to pull off the fittings.

http://www.parker.com/static_content...mHose_2013.pdf

I was planning on replacing my 2 stage Hardin pump with that stainless unit. Has your water pressure changed at all that caused you to look into this?

I have the hard wall Trident 1.25 inch hose, same kind that came on the boat originally and most boats from the factory. Have not seen the flex stuff, but looks interesting.

Did not install the pressure gauge until last season and I'm running 3 until motor warms up, then 1 to barely above at idle. Getting 20 to 23 psi from cruise to WOT, again this is first season with gauge.

My main issue is it is really hard to get to and remove the pump, hanging upside down. Hanging on to a 10 pound pump assembly trying to get the hose off (new hose). If someone made a quick connect that would work, this would at least make it easier. Could pop it off and then remove on the bench

There were “quick” disconnects on my 496 raw water plumbing. But you still had to get down there and release the clip that held them together with a small flat head and unclip it. Then still had to manipulate the hose enough to pull the two apart.

Number 17 & 18 in this pic from the 496 raw water parts diagram
https://cimg0.ibsrv.net/gimg/www.off...2caeaac3ee.png

Will look into that thanks

The original Merc bracket works the same way just doesn't have the slot. Will give it some thought and using grease may help. This one was the toughest due to new hose I believe.

I have 2 of Hardin's impeller housings (only) fastened to the oe pump. I didn't notice any abnormal wear to the impeller due to the slots. The wear plate looked just like yours, I flipped it over to use the other side and I plan on changing every other season as the impeller looked to be in such good shape. I'll only use Merc. impellers, Sierra are much flimsier and I'm not experienced enough yet to know of any others. I use OE hose and find it easier to get on an off the Hardin fittings, one of mine is even a 45* bend that goes under the engine toward the oil pan due to the engine mount. I typically unbolt the impeller housing then pull the hoses off as there's no way they'll slide off with everything in place; they're much too rigid.

Keith

I see the water pressure rating is 75psi but can't find a water suction rating. You're not having any issues with it collapsing? Has it been very abrasion resistant?

Thanks
Keith

I only use OEM Impellers, except this time since it came with the pump (New). I'm figuring the bump inside the pump is a manufacturing defect and I can fix it. Still not sure if I want to use it again, but then again its only removed every other year. I'll figure it out by spring

the impellor looks to be more than two years old,i say that from the bend in the flaps[;also called memory].when they get like that they wont move much water and soon will start to break apart in peices.i doubt the ss housing has any problems.

Appearances can be deceiving, and maybe its an old impeller from Hardin, but none the less its only 2 seasons old.

See post 11 and 33
https://www.offshoreonly.com/forums/...ps-safe-4.html

No issues with it collapsing, it’s still relatively rigid stuff but much more forgiving than the typical hose. As far as abrasion I don’t think I can comment on that, not in an abrasive environment

That's and idea, then just need to be able to get a wrench on it. Will look at it to see if a 1 1/14 wrench has a chance of getting at it.
Be nice if they made the quick attach hydraulic without the seal-off features. Wonder if that part can be removed?

There are a couple companies that make -20AN fittings as well, if you could get a crescent wrench down there. Aluminum are much more reasonable than SS, not sure if you run in fresh or salt.

Raising the motor up 3” was one of the big pros when I added my imco extension box. I remember I dropped a blue drain plug from the 496 under the motor, it took me and my wife to fish it out with our legs and feet.

i am not disputing that it has 2seasons,just saying it looks like more time on it,maybe it sat on harden,s shelf for several years before you got it.

the impeller was way over due for changing.When they fold over like that - they can not even come close to pumping enough volume of water thru all rpms. Its recommended to change out once per year weather you use the boat or not. Actually there is water volume output tests that also can determine impeller / housing changes.

And for the record the black plastic Bravo impeller housing is a proven pump and proven to flow enough volume of water until it needs changing.. In side by side testing the OEM Merc set up -- the impeller and black plastic housing provided the best water volume output tests new vs new compared to others. stock engine set ups.

Buy the OEM Merc kit --- 90 bucks and change once per year at the start of boating season. and be done with it. Never had a issue with that and once per year change. or after your lay ups are over how years that might be. Never run an impeller that has sat still for a year. Also some Marine OEMs recommend pulling out the impeller at winterization and storing it if you are going to reuse ( condition depending ) .

The older 2 piece OEM pump I like the best anyways. the old Mark IV race pump some call it

I've noticed zero water pressure difference between a new Merc impeller in a Harden housing vs. 2 years later. I therefore replace mine at 2 years.

While I only have one year with a pressure gauge, I have not seen any temp changes doing it every 2 years. When the impeller is removed they all look about the same.

Have not forgot about measuring the pressure at the thermostat housing to compare with the block pressure. Hope to get around to installing a second gauge this season.

Do think I'm going to go back to the composite housing next season, that thing is just heavy.

I converted to the stainless housing as well. The stock plastic housing and impeller would be toast after 1 season. With the Hardin, I pull the impeller when I winterize and by spring it looks pretty good. I have oil and water temp gauges but no water pressure. My temps are identical from year to year so I feel very comfortable getting 2 seasons out of an impellor. I also took a die grinder and ported my pump housing to remove rough edges and improve water flow. I run a crossover system with a 150 thermostat and I barely hit 150 unless I'm doing over 60. Water output out of the headers is significant even at idle. I like to hit it hard just before I get into the no wake zone to go down the river and then drop to an idle. My water and oil temps don't spike and temps drop right down quickly and I'm running an undersized cooler. I absolutely wouldn't go back to the plastic housing.