70HP Impeller Replacement Problem

ettenho1

Cadet
Joined
Jun 25, 2004
Messages
11
Hello All,<br /><br />I'm in the process of replacing my burnt out 1980 Johnson 70HP lower unit with a lower unit that was apparently from a 1982 70HP engine. The 1982's water pump impeller was in awful shape, and I had to cut it off to get it off of the driveshaft. When I did this, I noticed that the impeller and driveshaft were quite different between the two units, in that the 1980 shaft had a flat indented spot and used a small metal rod for a key, whereas the 1982's shaft protrudes in ridges that form a key that the impeller fits onto. <br /><br />However, when shopping for impellers, everyone is trying to sell me the same item regardless of whether it is a 1980 or 1982 lower unit, so I'm reluctant to buy just to have to ship it back. An impellar that would fit my 1980 unit would definitely not fit my 1982 unit. What's going on here, and how do I find the impeller I need? <br /><br />Thanks much,<br />Mark
 

marinemech1

Chief Petty Officer
Joined
Mar 26, 2005
Messages
623
Re: 70HP Impeller Replacement Problem

the impeller hub is still stuck on the drive shaft
 

ettenho1

Cadet
Joined
Jun 25, 2004
Messages
11
Re: 70HP Impeller Replacement Problem

Hot damn - you must be right! Any advice on how to get that corroded brass ring off my driveshaft?
 

marinemech1

Chief Petty Officer
Joined
Mar 26, 2005
Messages
623
Re: 70HP Impeller Replacement Problem

try heating it gently so you don,t burn up seals in gearcase
 

Walker

Captain
Joined
Jun 15, 2002
Messages
3,085
Re: 70HP Impeller Replacement Problem

If you are careful you can cut it off with a cold chisel. I mean very careful. Don't bugger up the drive shaft. If you can get it split on one side it will come right off.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: 70HP Impeller Replacement Problem

A Dremel tool with a fiberglass reinforced cutting disc will have it off in about 10 seconds... Cut it ALMOST all the way through then split it open with the cold chisel method outlined above... That will prevent getting the shaft all marfed up...<br />- Scott
 

rwcreigh1

Petty Officer 2nd Class
Joined
Feb 13, 2005
Messages
199
Re: 70HP Impeller Replacement Problem

becareful if using heat not to heat the shaft and bend it.it would take a lot of heat but just wanted to let you know.
 
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