impeller change questions on a 72 Johnson 20 hp

JoeLo

Cadet
Joined
Apr 13, 2009
Messages
9
Hi guys,
I was hoping to get a little advise from the gurus. I am new to motor repair and am concerned about a job I just did. I eplaced the impeller and plate on my 20 hp and in doing so I removed the drive shaft from the lower unit. I removed the oring at the top of the shaft ,slid of the pump housing,impeller and plate, replaced with new and reassembled. Every thing went back together way to easy! I made sure the curvature of the rubber impeller matched the old one . My biggest concern is the drive shaft. Is there a wrong way to reassemble them? also I replace the lower unit lube and it looked like chocolate milk!. One other thing...this motor has been stored in a heated area since 1995. Would that cause the lower unit oil to look like it did?

Advise would be greatly appreciated

Thanks
 

Mas

Lieutenant Commander
Joined
Oct 3, 2006
Messages
1,656
Re: impeller change questions on a 72 Johnson 20 hp

Milky lower unit lube oil represents water intrusion into the lower unit. It may be time to reseal the LU...or at the very least do a pressure/vacuum test to see which seals are leaking.

You may get lucky also in that the drain/fill plug washers were reused (a no-no!), and just replacing the washers after refilling with fresh lube will do the trick. If so, recheck the lube oil after running on the lake to ensure no water is in the case...which will destroy your LU.

Seal kit...$50

LU...lots!


MAS
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: impeller change questions on a 72 Johnson 20 hp

always replace the seals on the screw plugs. BRP part # 0311598 **WASHER, Fill & drain seal
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: impeller change questions on a 72 Johnson 20 hp

There is only one way to reinstall the drive shaft, so don't worry about that (as long as you did put the o-ring on the top).

As for that oil: Don't get all bent out of shape over it. How long since it has been changed? Maybe even never? Change it and recheck it after running a few hours. Minor water intrusion is not abnormal. That is why the factory said to change it regularly. Of course serious leaks should be fixed.
 

JoeLo

Cadet
Joined
Apr 13, 2009
Messages
9
Re: impeller change questions on a 72 Johnson 20 hp

Thanks! I picked up new LU lube today and will give it a test run this weekend.
As usual you guys are the best!
 
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