Tohatsu 9.8 O/B - Impeller change

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Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Need to change a 4 year old impeller on my 4 stroke Tohatsu 9/8. In the past I took my O/B to a mechanic and had him do it. But I want to know how to do this job myself. Read the service manual, have the Tohatsu kit (impeller, shell, gaskets, etc). This looks way more complicated than prying the impeller out of my Yanmar auxilliary (which I thought was a ridiculously difficult task).

Looking for wisdom and advice by them that have been down the path of Tohatsu outboard motor impeller replacement. How do I make this annual job as painless as possible?
 
Apr 8, 2010
1,600
Frers 33 41426 Westport, CT
it normally takes all of 20-30 minutes to change the impeller once you have done it once.

4 bolts holding the lower unit, and (at least on my 2 stroke) a pin and C clip on the shift linkage. The lower unit just drops down. The pump housing has 3-4 more bolts to remove, then the housing slides up and off the shaft, the rest should be self explanatory. Just make sure to turn the shaft as you slide the housing over the new impeller to seat it in the proper rotation.

When you reinstall the lower unit a little turn of the prop (if you left it in gear) or a small tug on the starter rope will help align the shaft spline to the engine to allow it to slide up.
 
Nov 6, 2006
9,225
Hunter 34 Mandeville Louisiana
Yup.. The linkage is the only tricky part. Sometimes handy to have two folks the first time.. One to hold the lower unit up as you remove the linkage connection.. Then watch the pump discharge hose as you slowly remove the lower unit.. Once the lower unit is off, the rest is really straightforward. Put anti-seize paste on the threads when ya go back up with it.. Good Luck !
 
Feb 20, 2011
7,783
Island Packet 35 Tucson, AZ/San Carlos, MX
Like Brian says, it's a quick job.
If your 9.8 is anything like my 4 horse Nissan (and I'll bet it is), first, mount it high enough so when you pull out the lower unit, the shaft has room to exit the housing.

Pull the prop, then open the portal to access the shift linkage in the housing.
Pic 1, the black circle.

Loosen the screw on the shift linkage, then you can unbolt and drop the lower unit.

Careful not to lose the locating pin that rides along the shaft.

HTH.
 

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Oct 30, 2012
8
MacGregor 25 Chesapeake City
The shift linkage on the four stroke is actually a roll pin, which you drive out with an 1/8" punch. The rest is pretty easy and covered above, just allow enough time to put it all back together the day you do it. oh... and drain the gear oil first if you're going to change the gaskets.

Just curious, this motor is for your dinghy, right?
 

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Thanks folks, after reading your instructions, looking at the photos, diagrams and video I feel completely capable of tackling this job! :dance:

And yes, this is my dinghy motor. But lashed to the quarter with this motor, I can move my 10 ton boat.
 

Gunni

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Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Change completed. Placing the transmission in gear prior to dis-assembly allowed me to use the prop to align the drive shaft splines on re-assembly. Getting that linkage pin out and back in were the toughest parts. What an amazing collection of compact mechanical systems.
 
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