Raw Water Pump - Impeller Indmar/Johnson

[CazaSub83]

I just bought a 1999 Malibu Sportster LX. Today I tried replacing the impeller (Johnson pumb/Indmar). This is something I've done in the other boats I've own. What I thought was a 20 minute thing became an hour just to remove the old impeller. Now trying to put the new impeller has become a nightmare. After various attempts I noticed the pump shaft was marking the brass in the impeller. I checked  the old impeller and it was easy to tell that the brass part had the marks of an extremely tight pump shaft.

After checking YouTube videos from Skidim and others I can only think the tolerance on the pump shaft is on the high end. Has someone had this challenge? How did you resolve it? Thx.

 

[justgary]

12 hours ago, CazaSub83 said:

I just bought a 1999 Malibu Sportster LX. Today I tried replacing the impeller (Johnson pumb/Indmar). This is something I've done in the other boats I've own. What I thought was a 20 minute thing became an hour just to remove the old impeller. Now trying to put the new impeller has become a nightmare. After various attempts I noticed the pump shaft was marking the brass in the impeller. I checked  the old impeller and it was easy to tell that the brass part had the marks of an extremely tight pump shaft.

After checking YouTube videos from Skidim and others I can only think the tolerance on the pump shaft is on the high end. Has someone had this challenge? How did you resolve it? Thx.

 

Congratulations on your purchase, and welcome to the crew.

Photos would help.  I would blame an aftermarket impeller hub before I blamed a genuine Johnson shaft.

One way to assist your impeller with coming out is a bit of dish soap.  Some people report using WD-40.  Another help is to pull your safety lanyard and crank the engine with the impeller cover off.  The impeller will begin to walk itself out of the housing so you can get a good grip on it with needlenose pliers.  A little more soap on installation will help the new impeller slip into its new tiny house.

[CazaSub83]

Thanks Justgary. I cannot figure out how to upload a picture.  I hope the description here helps. The impeller I removed was a genuine Johnson Impeller. The shaft scratched a perfect circle in the brass all the way to where the shaft ends. If you put your finger or a tool in the brass you can fill the circle is actually brass scratch. When I attempted inserting the new impeller it was making the same marks. I only inserted it 1/4' into the shaft. A mechanic friend stop by a basically said he had never seen something like this. 

I contacted the original owner since the previous owner hadn't changed the impeller the two years he owned the boat. Original owner confirmed that removing the impeller was extremely hard and the only way to get the impeller in was by pressing it in with a 2by4 and tapping it with a hammer! This is a Johnson/Indmar 68-5001 and the impeller being used is a 812B. I just wonder if there was/is another impeller designed for this pump.

 

Edited May 16, 2022 by CazaSub83