91'-90hp re-assembly help & advice

[Bigprairie1]

Ok, as I posted in the fall I am trying to put together a 91' 90hp force from a 'broken lower unit' motor I bought last summer. Supposedly the power head is good. I bought a good used lower unit for it and now I have to get these two together. I am hoping to have this motor as a spare or perhaps put it on a second boat for me and a buddy of mine to use.
What I would like to know is should I just do the impeller...or should the entire water pump be replaced? (or other stuff too?) How do you tell how far to go on this? The motors serial number is 908A91H.
Note: the lower unit I bought looks very good and it appears to have a very nice intact looking water pump unit it on it...although I have not checked its impeller....yet.
Next question: what does the little rubber flexible tube connect to that is connected down into the front of the lower unit?
Next question: can the motor be compression tested (successfully) with the lower unit removed?...any danger of anything getting out in the process or over spinning or other things to watch for?
Next question: prior to doing the impeller...or the water pump...or both? is there any major step to do or something to check or align before bolting the unit up onto the motor?
Next question: do these impellers and/or water pumps vary a lot in these years? (referring to the serial number listed above)...or are they all pretty common?
Ok guys...many thanks in advance...hopefully you can wade into this with some much needed advice.
BP

 

[roscoe]

Re: 91'-90hp re-assembly help & advice

Just do the impeller, unless you find a mess when you open it up.

Tube is unused, connected to old style speedometer at one time.

Compression test can be done now.... but do not let the engine start !

Put lower unit into forward gear, and put the shift handle on the controls into forward gear.

Impellers changed over the years, not every year, but occasionally.

The impeller was the same for 1990 - 1994, 90 hp and 120 hp models.

 

[Bigprairie1]

Re: 91'-90hp re-assembly help & advice

Just do the impeller, unless you find a mess when you open it up.

Tube is unused, connected to old style speedometer at one time.

Compression test can be done now.... but do not let the engine start !

Put lower unit into forward gear, and put the shift handle on the controls into forward gear.

Impellers changed over the years, not every year, but occasionally.

The impeller was the same for 1990 - 1994, 90 hp and 120 hp models.

Thanks Roscoe, this info helps immensely. I'll start looking for a new impeller (ebay perhaps?).
I have a wiring harness that I'm hooking up to the motor which should allow me to spin the motor over with a key/switch arrangement.
Is there an easier, less complex way to spin it over other than completely wiring it up?
Again I appreciate the help and I'm hoping the compression test turns out positive.....a spare motor would be great.
The 'project' motor has a trim/tilt unit and I'm at odds whether to remove it from this motor and put it on my current 'runner', which has none.
First things first tho'....compression test and I guess I'll go from there.
Many Thanks
BP

 

[roscoe]

Re: 91'-90hp re-assembly help & advice

Part number 18-3017 in the iboats megamall.

All you should have to wire up is a ground wire to the battery. Then touch a jumper cable to the starter to spin it over.

 

[Bigprairie1]

Re: 91'-90hp re-assembly help & advice

Part number 18-3017 in the iboats megamall.

All you should have to wire up is a ground wire to the battery. Then touch a jumper cable to the starter to spin it over.

Perfect, can do.
Another quick question for ya': If the motor has not been turned over in a couple of years (which it hasn't) what would be the best thing to spray in the cylinders prior to cranking?
ie: shot of two stroke oil? or?...maybe let it sit over night with something in there? I don't think the motor is frozen or anything like that but if I can do a bit of a 'prelube' to minimize any ring grab or gouging I would.
I ask this because I hear that the Force engine have sensitive/delicate piston rings and would not want to risk snapping one if the engine is currently a little 'dry' in the cylinders.
Again, many thanks. Getting good info up front always makes things go easier and decreases the likelihood of permanent damage, especially if you are new (as I am) to outboard motor repair.
Thanks!!
BP:redface:

 

[roscoe]

Re: 91'-90hp re-assembly help & advice

2 stroke oil, Seafoam Deep Creep, even wd-40 will work

 

[Bigprairie1]

Re: 91'-90hp re-assembly help & advice

Thanks Roscoe, I appreciate the help. When I get 'er all back together I'll post the results...hopefully they will be good and I'll have a spare motor for my boat...or a good motor for a second boat.
All good and again, thanks.
BP