1983 80 hp Merc Complete Water Pump Replacement

[83 Merc]

1983 80 hp Merc complete water pump replacement. A two part question for you pros:

Dropped LU and disassembled water pump. Lower case part of water pump pried off easily, leaving behind the lower round piece, which has a seal inside it and an o-ring around it, and is in there pretty good. I can see (and smell) gear oil on the underneath of the lower water pump case only, and gear oil on the top of the round piece only. All the rest of the inside parts of water pump do not have any oil on them. My question is should I wrestle to get this lower round part out and replace it because I see gear oil on it, and because I have the parts to repair it, or could this oil on these particular parts be ok?

There is NO water in the LU, just wanted to do as complete of a job to the pump as I could.

Second part of my question is: the new lower water pump case part has the lower round part described above pressed into it. I lightly tried to separate them and am afraid I'll destroy the case by trying to separate them. So, if the answer to question 1 is leave the round piece in and just proceed from there, then how am I getting the new pressed parts apart to proceed?

I hope that my explanation makes sense to you guys, and I thank you for the help.

 

[saumon]

Re: 1983 80 hp Merc Complete Water Pump Replacement

The lower case you described is the waterpump base and the round piece is the drive shaft oil seals (there's two of them, face to face). If it's included, yes you should remove the older ones and it's very easy. You only need to remove the drive shaft and pry them out (seal puller or screwdriver).

If you can specify your engine serial number, i'll post a schematic identifying each parts.

If you don't mind: why are you replacing the entire w/p? Most of the time, you only need to replace the impeller, did the pump body was destroyed?

 

[83 Merc]

Re: 1983 80 hp Merc Complete Water Pump Replacement

Thanks for the reply. Guess I should have given a little history on the motor.

I bought a very neglected motor on a 21? aluminum Starcraft. Changed gear oil when I bought it and ran the boat twice. Boat ran well on first outing, but was severely bogging down on the second outing. Motor wouldn?t throttle up much past idle speed. Oil began leaking from prop area as soon as I pulled the boat out at the launch.

So I figured I would repair all of the basics - carb rebuild, fuel pump rebuild, and complete water pump. Thought that the leaking oil was gear oil and a complete water pump might solve that problem. That is why I bought a complete pump kit.

Drained lower unit and oil seems clean with no water in it. It is a brownish color, where the leaking oil was black. Now I am thinking the leaking oil was unburned 2 cycle oil from the motor bogging down.

Now I think maybe I should install new parts on top of the existing drive shaft oil seals that you named, and see how things go. As a novice, I probably shouldn?t pull the drive shaft if I don?t have to.

Which leaves me with a question: what about the very small amount of oil on top of the drive shaft oil seals and on the bottom of water pump base. Should I be worried about this? Is a thin coating of oil here normal?

 

[saumon]

Re: 1983 80 hp Merc Complete Water Pump Replacement

If you check your gear oil regulary and there's no signs of water intrusion, don't worry about it.

For your information, you usually only need to change the impeller (a lot cheaper than the whole w/p kit) as it's the only wearable part under normal operations. Other than this, oil seals on both shafts (driveshaft, shiftshaft and propshaft) had to be replaced when there's evidence of water in the gearcase, as it's hard to tell wich one is leaking.

 

[jebeebe]

Re: 1983 80 hp Merc Complete Water Pump Replacement

As there is exceptions to all rules, here's one. I replaced an impeller and the motor still wasn't pumping enough. Got discusted and replaced the whole pump, and it fixed the problem. There must have been a hole or crack in the lower houseing??????????????? You're right a new impeller should fix it..............Jerry

 

[wayne cav]

Re: 1983 80 hp Merc Complete Water Pump Replacement

hi can you help replased the water pump but cant get the bottom of the leg back in goes so far then stops the spline wont go in seems to a small pin in the way how do i do it thanks

 

[jebeebe]

Re: 1983 80 hp Merc Complete Water Pump Replacement

the pin on the end of the driveshaft is spring loaded and will compress as the lower unit is bolted up. It will however require very little pressure so if it is tightening up hard, don't force it, there may be somthing else wrong. The pin is to "preload" the berring below the waterpump. You may have somthing else causing your trouble, such as the water tube,or the shift shaft, or maybe you just need to move the flywheel.....................Jerry