1998 Yamaha 9.9 High Thrust Lower Unit

MTBoat

Petty Officer 2nd Class
Joined
May 11, 2011
Messages
143
Picked up a 98 Yamaha 9.9 High Thrust with remote electric start and shift earlier this year and there were videos showing it running in a tank etc. Decent deal, but, had to meet halfway to get it, so, had to trust a bit too. Started it before putting controls on an ran very nice.
Today, after putting it all together including shift cables and such, it seemed (not running) that when I shift to reverse the prop is engaged, but when shift to forward kind of but not totally....
Then, I noticed that at the prop, it was movable in or out...if I pushed it in a little it engaged forward fine,,,,but generally it was as if there was an independent house carrying the prop, yet, no leaks of oil (oil level good and no water). I never had this type motor before and never have see anything quite like it.
Am I missing something here, or does anyone have this experience or can explain what is normal, or what is going on?
I did not want to run it in or out of water on muffs before I can understand this.
Thanks
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Picked up a 98 Yamaha 9.9 High Thrust with remote electric start and shift earlier this year and there were videos showing it running in a tank etc. Decent deal, but, had to meet halfway to get it, so, had to trust a bit too. Started it before putting controls on an ran very nice.
Today, after putting it all together including shift cables and such, it seemed (not running) that when I shift to reverse the prop is engaged, but when shift to forward kind of but not totally....
Then, I noticed that at the prop, it was movable in or out...if I pushed it in a little it engaged forward fine,,,,but generally it was as if there was an independent house carrying the prop, yet, no leaks of oil (oil level good and no water). I never had this type motor before and never have see anything quite like it.
Am I missing something here, or does anyone have this experience or can explain what is normal, or what is going on?
I did not want to run it in or out of water on muffs before I can understand this.
Thanks

not sure I understand what you are saying about the different house

if motor is not running or the prop not being turned ,the shift clutch dogs may not be lined up properly to lock into gear.
maybe his is close to what you are trying to explain
 

MTBoat

Petty Officer 2nd Class
Joined
May 11, 2011
Messages
143
I think what I am trying to say,,,is that you can literally grab the prop and push it inward about 1/4 to 1/2 inch,,,then it will engages the forward gear solidly,,,not running of course.....I mean is that prop supposed to be in a solid "housing" or able to kind of float out or in a half inch or less?

It sits in the out position,,,BTW,,,,,and if its loose inside somehow,,,, how come no oil leaks?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
take the prop off and see if the shaft is moving that far or is it just the prop sliding on the splined shaft

maybe you are missing the thrust washer
 

MTBoat

Petty Officer 2nd Class
Joined
May 11, 2011
Messages
143
Does anyone have a link to the actual thrust washer kit for this year 1998 of yamaha 9.9 high thrust kicker motor? I seem to find a lot of chioces, but they don't look like what is on this one, unless someone put the wrong washer and prop assembly on it?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
so does that mean the shaft is not moving back and forth?

did you think to ask the guy you bought it from what was going on with the prop?
what he put on it ,
when,
where he got it from,
any part numbers?
 

MTBoat

Petty Officer 2nd Class
Joined
May 11, 2011
Messages
143
When I took all the items off the shaft, you can move the shaft in and out about 1/4 inch.
Having not had this unit before, it appears that the thrust washer doesn't fit far enough over the inside of the shaft to tighten the unit to the frame when you screw the nut on,,,,however, if the shaft is not supposed to move at all with all that stuff removed, I assume we have another issue inside somehow? I'll probably take it to a mechanic from here as I don't seem to have the expertise to analyze it.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
my C40 does not have that slop in prop shaft when prop is on, but I could not say if it does with the prop off or not as I have not checked.

If you pull the prop up tight against the housing , the prop will not turn because it will be rubbing on the housing,
but I do not think it should have 1/2 inch slop

being you do not know much about this I would recommend you have someone that does have a look at it
and like I said before ask the person you bought it from some questions
 
Last edited:

MTBoat

Petty Officer 2nd Class
Joined
May 11, 2011
Messages
143
Thank you all for your input, I'm going to put a brand new complete lower unit on this one for $950 out the door and have something I can truly depend on....the powerhead is in great condition.
 
Top