Merc outboard impeller replacement

[jamima]

I've read some good posts on this site to impeller questions but would like to make sure they apply to my outboard--1988 Merc 100hp ser#OB311227. I bought a manual but can't lay my hands on it and I'm anxious to get out on the water for the spring Rockfish run (Chesapeake Bay). Any help, the more specific the better, would be welcome. I plan to do this tomorrow morning even if I have to use the previous posts as a guide. Thanks in advance.

 

[Chris1956]

Re: Merc outboard impeller replacement

Jam, Most any procedure for a 4/6 cylinder Merc outboard or Mercuriser Alpha waterpump rebuild is applicable to your motor. The smaller Mercs and the OMC procedures are different.

A couple of tips. Put the motor in neutral before you drop the LU. Don't forget the bolt under the zinc trim tab. The impeller has a key that locks it to the drive shaft. The white plastic tube fits into the pump output, and helps guide the motor copper tube into place. The large rubber washer is the slinger, and fits around the driveshaft tight to the top of the waterpump housing. Replace the oring under the waterpump base. match it up since the kit will have extra gaskets and orings. Grease the driveshaft splines before reinstalling the LU.

 

[jamima]

Re: Merc outboard impeller replacement

Thanks Chris.
A previous posting stated, "Do not grease the drive shaft where it meets the crank shaft. It will seal and seize together." Is that different than greasing the splines?

 

[Chris1956]

Re: Merc outboard impeller replacement

I did not see the other post. I think he is in error. You need to grease the driveshaft splines or they may corrode into the crankshaft. Also grease the propshaft splines before installing the prop, or it will corrode to the propshaft.

I boat in salt water so I put some grease on the entire driveshaft, waterpump to splines. I use saltwater resistant Boat trailer wheel bearing grease for all the areas then need grease.

 

[jamima]

Re: Merc outboard impeller replacement

Good advice. Thanks again Chris.

 

[Missxena]

Re: Merc outboard impeller replacement

I guess I'm a little late but for anyone else reading, this how-to helped me do
mine the first time.

 

[nitroman946]

Re: Merc outboard impeller replacement

Missxena

I do have to say you have done a great job at putting this impeller replacement folder together. The pic are great they will let most people complete this job with out spending $150.00 or more. I also like to change the pump each year. Ok happy fishing just wanted to tell you GREAT JOB.

Big Tom