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496 water impeller change..

adam909

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Over this past weekend i noticed my water temp shoot up then back down but stayed at 180 but never really went back down to where it usually sets 150-165. So i figured something is up with the water impeller.. Took it apart and sure enough i lost some fins, the impeller wasn't toast but 2 fins was gone.. Glad i didn't keep running due to it would have been really bad trying to fix it on the water. This is the first time doing this but just figured it out. I found all the rubber pieces up againts the screen as well as flushed it out going back to the pump and got a couple more pieces... I got it all back together and took the boat down to the ramp and started the boat.. I didn't get any water coming out of the exhaust for like 45 seconds with a couple revs of the motor and then i got water coming out of the pipes.. Ran the boat all day and water temps was normal. Is this normal? Is there a way to prime the pump before starting?

Before i did the fix i pounded the internet and learned there was a problem with scoring on the brass housing. Before i put it back i looked it over and you can see where it rub but really no groves or scoring. Later that day i did buy a stainless steel wear plate and gaskets.. So i guess the next time it goes out ill replace it with the wear plate...

My boat is a cookie cutter magic deck and what a pain in the ass it was to change... If that fuel pump wasn't in the way it would be a lot easier. is there any tips on making this job easier? i had to leave the housing attach due to i couldn't get my arms under to cut loose the two hoses loose.. I'm sure if i could get the hoses off it would been a lot easier to change out the impeller... what a dumb design... Thanks adam
 

djunkie

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You should see how hard it is to get to on my brothers new to him tritoon with a 350 in it. I told him fuck it. Pay someone to do it. Lol
 

3queens

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if you can removing the back seat always helps
15mm gear wrench with swivel head helps (the brand name not the cheepy knock off)
ratcheting screw driver with 10mm socket for hoses helps
and being part contortionist helps :D
best way to prime is hook up your water to your drive unit earmuffs
 

3queens

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untitled.png
pic for ya
 

XX14

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I just replaced mine with the Hardin marine pump, better design, and installed the stainless steel tee and plumbed a hose connection. No more muffs and the impeller immediately has water.
 

adam909

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I just replaced mine with the Hardin marine pump, better design, and installed the stainless steel tee and plumbed a hose connection. No more muffs and the impeller immediately has water.

do you have any pics of the stainless tee? did you install this so you can prime it easier?

The hardin replacement pump looks like a better pump. would adding stainless wear plates to the stock pump do the same thing and cheaper as well?
 

Racey

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The 496 pumps are notorious for wearing internally and making it impossible for them to prime. Switch the pump out for the Hardin Stainless pump that has changeable wear plates next time you have it out. It will continue doing this until you change the pump. They are a shitty design from the get go, merc really dropped the ball on them.
 

Outdrive1

Outdrive1 Marine Sales https://www.outdrive1.com/
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The intake hose has a quick release on the other side of the motor mount if it has the cartridge filter inside the fuel pump housing. The other hose you can get once it's all loose and you pull it forward and or down.

Remove the two ten mm bolts in the tensioner pulley and get it out of the way. Then the two 15 mm bolts that hold the bracket on are accessible.

The wear plates that go in the brass housings are money. They work and solve the problem. Probably a third of the cost of the Hardin pump also.

I install that kit in almost every 496 I do. It's not worth the time to take it apart again when it won't prime. With the kit it's good every time.
 

adam909

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bringing this back to from the past.. question.. last time I changed it i didn't pull the whole assembly due there there where some 1/8" air lines attached? How do safely remove the air lines so that i can take out the whole assembly to change the impeller.. Taking it out seems a lot easier then trying to put it back together in the blind like i did last time.. thanks..
 

Runs2rch

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bringing this back to from the past.. question.. last time I changed it i didn't pull the whole assembly due there there where some 1/8" air lines attached? How do safely remove the air lines so that i can take out the whole assembly to change the impeller.. Taking it out seems a lot easier then trying to put it back together in the blind like i did last time.. thanks..

Push the air line in and then lift up on the round plastic tab. While lifting the line slides out.
 

Outdrive1

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Over this past weekend i noticed my water temp shoot up then back down but stayed at 180 but never really went back down to where it usually sets 150-165. So i figured something is up with the water impeller.. Took it apart and sure enough i lost some fins, the impeller wasn't toast but 2 fins was gone.. Glad i didn't keep running due to it would have been really bad trying to fix it on the water. This is the first time doing this but just figured it out. I found all the rubber pieces up againts the screen as well as flushed it out going back to the pump and got a couple more pieces... I got it all back together and took the boat down to the ramp and started the boat.. I didn't get any water coming out of the exhaust for like 45 seconds with a couple revs of the motor and then i got water coming out of the pipes.. Ran the boat all day and water temps was normal. Is this normal? Is there a way to prime the pump before starting?

Before i did the fix i pounded the internet and learned there was a problem with scoring on the brass housing. Before i put it back i looked it over and you can see where it rub but really no groves or scoring. Later that day i did buy a stainless steel wear plate and gaskets.. So i guess the next time it goes out ill replace it with the wear plate...

My boat is a cookie cutter magic deck and what a pain in the ass it was to change... If that fuel pump wasn't in the way it would be a lot easier. is there any tips on making this job easier? i had to leave the housing attach due to i couldn't get my arms under to cut loose the two hoses loose.. I'm sure if i could get the hoses off it would been a lot easier to change out the impeller... what a dumb design... Thanks adam

Did you have the red hose for water intake? If so don't try to take the hose clamp off at the pump. There's a quick release by the starter. You take the whole assembly off with it.

All the bolts are metric. I can do them all by feel because a lot of times you can't see anything. Take the tensioner pulley off first. Once it's out of your way the bolts for the bracket are accessible. Magic's aren't the hardest to do imo.
 
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