water pump 75 merc 20hp

F

farscapehw

Cadet
Joined
Mar 17, 2009
Messages
12
i got my mercury 200 20hp running, (thanks for the help with the electrical stuff. it was a short in the orange wire to ground for the ignition switch up front of the boat)

now my impaler isnt even trickling water. so i took the nut on the front of the lower unit loose and the nut above the prop off and the front of the unit is loose but the rear near the prop is not coming loose. is there another bolt?

there is an aluminum plate with no bolts in it above the prop and above that from the top there is a tiny round hole i see another bolt in but cant get a socket on.

anyone have the procedures for changing the water pump?

serial # 4148481
 
J

jeffdjpeat

Petty Officer 2nd Class
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Mar 25, 2009
Messages
125
Re: water pump 75 merc 20hp

i have a 91 merc 60hp i just did an impeller change on, maybe a bit the same. mine has 2 bolts, one on either side of the leg, above the water intake peice, then above the prop you mentioned a bolt down in that hole it needs to come out, it is bolted to the aluminum plate above the prop, or at least mine was. and then i had another bolt right in front of my aluminum plate yours might not. but in total i had to remove 4 bolts to take the bottom end off. then be carefull, it might slide right down, i almost lost a finger when mine dropped.
hope this helps
 
J

jeffdjpeat

Petty Officer 2nd Class
Joined
Mar 25, 2009
Messages
125
Re: water pump 75 merc 20hp

p.s you may need a 2-3" extension on your wrench to get that bolt above the prop. but the socket should just barely fit through the hole.
 
F

farscapehw

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Mar 17, 2009
Messages
12
Re: water pump 75 merc 20hp

i got the one above the prop off with a thinwall 14mm. the one in the hole bolted to the plate is larger than the hole, there is no way it is coming out.

what are these 2 you say are on either side of the leg? is the section between the engine and the lower unit called the leg?
 
S

Starppy

Petty Officer 3rd Class
Joined
Mar 23, 2009
Messages
84
Re: water pump 75 merc 20hp

The bigger mercs of that era had a bolt hidden under the zinc trim tab. There was a bolt on either side of the drive shaft housing and the one under the trim tab. You have to remove the trim tab to get the third bolt out.

The 200 might be different, but it was like that on the 650 and 500.
 
5

56 rude

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Aug 8, 2008
Messages
198
Re: water pump 75 merc 20hp

just checked a merc manual and though its for 40 hp and above it looks like you have to go from the top ,i had a mariner 60 hp and i had to use a thin walled socket like one of the other guys said.shine a light in the hole its possible that it may use a large allen bolt also, ive seen them used before.
 
F

farscapehw

Cadet
Joined
Mar 17, 2009
Messages
12
Re: water pump 75 merc 20hp

whoop! thanks dude! it was an allen bolt but the hole had crudd in it so i couldnt see. got it off and the pump is completely destroyed. going to go get one now. thanks!
 
5

56 rude

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Aug 8, 2008
Messages
198
Re: water pump 75 merc 20hp

your welcome ,i was looking at the manual and it showed a guy holding the bolt and the more i looked at it the more it looked like a round head,thus a allenhead bolt.i wonder if my mariner was the same and i just forgot because its been 6 years since i owned it.
 
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