# Replacing a water pump in a 35HP johnson seahorse.



## tholdah (Apr 13, 2009)

Sorry if this is somewhere on the forum already, but there are soooo many posts now (congrats Jim on the success of the site). 

We have a mid-late 70's Johnson 35HP Seahorse, and I'm concerned about the water pump. It will pump water, but we need to be moving at a pretty good rate for it to start pumping water. I really don't want to buy the entire service book for this one repair, so is there a place I can get just the pages for this repair? Will there be any special tools I will need? Thx for the help. THE SEASON IS ALMOST HERE!!!! =D>


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## bassboy1 (Apr 13, 2009)

Send me a PM tomorrow reminding me, and I will snap pics of those pages out of my manual tomorrow evening, and send them to you. However, it is real simple. 

You need to disconnect the shift rod. On some, there is a plate on the side of the midsection you remove with a phillips screwdriver, and then undo the shift rod attachment bolt with a 7/16 nut driver. On others, you have to take the hood off, and unbolt the one bolt connecting the shift rod to the shift lever. I can't remember which that motor has.

You will see the seam where the lower unit attaches to the midsection. There should be a number of bolts around the perimeter of the gearcase, and one hidden one. The hidden one is going to probably be behind the zinc anode/torque tab, if yours is the new gear case style, or it will be from the top going down (right out in the open - not really hidden) if it is the old gearcase style. 

Then, the gearcase should slide down. Be sure to slide it straight until the shift rod and driveshaft are out. Sometimes you have to wiggle the flywheel to get the driveshaft spline to let go. Now, stand the lower unit up. I usually get a big carpenters clamp like the one in the link below, and clamp it around the skeg. It will then stand the gearcase up nicely. 
https://images.marketworks.com/hi/51/51407/ha-tz7904.jpg

Then, take the O-ring off the top of the drive shaft, and don't loose it. Now, pull the 3 or 4 bolts off the top of the water pump assembly (the case surrounding the drive shaft), and slide it off the top. You should now see the impeller. Slide it off, and DO NOT loose the woodruff key. If you are doing the full rebuild kit, you may have the plate on the bottom, and sometimes even the impeller cup. Depends on what your kit comes with, or if you just replace the impeller. Now, start reinstalling parts as they came off. Impeller WITH WOODRUFF KEY, housing, bolts, O-ring at the top (easy part to forget). When you put the impeller in its housing, make sure to spin it in the direction that the motor will, and have all fins facing the same. If you have one backwards, it can break off when you fire the motor up.

Now start to slide it up the midsection. You will need to make sure the water lines line up correctly, as do the shift rod and drive shaft. Reinstall the bolts (I can't remember torque specs, but since it is into aluminum, it is probably 20 - 30. I will look that up for you when I send pictures. Reconnect your shift rod, and give 'er a test run. 

Some advise to drain the gear lube before starting, and replace it when finished, and while it sometimes is nice, I have done them both ways. If you haven't replaced it in a while, go ahead and do it now. Be sure to replace the drain and vent hole washers, as they aren't good to be replaced.

Good luck.


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## turne032 (Apr 14, 2009)

I do not want people to mistake what i am trying to get across. PLEASE, PLEASE, PLEASE, Check your water pump if not every season, but at least every other season. 

But, some motors will not (pee) untill the motor heats up a little or rpms increase above idle speed.

And if your motor is not (peeing) it doesnt always indicate that its a water pump problem, it could be a dirt dober or dirt inside the (pee tube).


But ALWAYS CHECK YOUR WATER PUMP.

just sharing my .02


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## bassboy1 (Apr 14, 2009)

If you haven't replaced it in 2 years, do so now. 15 - 20 bucks, and 30 minutes of work is a good piece of mind.


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## tholdah (Apr 14, 2009)

Thx for the info. Is there a way to know if the water pump is worn without disassembling the unit? When I bought the engine, the guy said it was replaced recently, but they all say that right! 

I may do it regardless....just to be safe. I am not sure if there are engine numbers on the unit...I don't assume it's a universal item? That's rediculous right :lol:


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## bassboy1 (Apr 14, 2009)

Best place to buy online would be iboats.com. Just click on engine parts - Johnson engine parts - Johnson cooling parts - impellers. Then, hypothetically it will come up with a spreadsheet of motor models. Scroll down to your model (you will need exact year, as there was a change in gearcase design during the late 70s, and they may or may not have changed the water pump design), and it should have either a Sierra or Mallory part number, or both. Both are good quality aftermarket parts. Were they the exact same price, I would go with Sierra, but I have no reason behind that. 

The other option is to get an OE part from them. If they are local, and good people, then by all means support the local guys in times like these. If it is like some of the marinas around here, I don't give them a penny of mine.


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## bassboy1 (Apr 14, 2009)

Here is a link to the iboats.com page for the impeller. Need to know the exact year of yours. 

https://www.iboats.com/Johnson_Impellers/dm/cart_id.462353285--session_id.961191252--view_id.271268


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