1991 Force 150 prop forward seal question

[shushry]

Hi all - great forum and fantastic info here. I've been searching high and low for a direct answer here and can't seem to find anyone with the same issue.

I've got a 1991 Force 150 and finally getting around to needing to replace the prop. The issue is that most props i've encountered have bout a 1/8" thickness on the forward seal. However, my existing prop's is only about 1/16" - so any compatible prop (size, spline ct, etc) won't quite fit in the lower unit gear case correctly.

In digging around I see some eluding to something called a "small labyrinth" in some of the mercury quicksilver series (see this post and this post)

Force and mercury seem to be related in this arena - is this correct? And, is this "small labyrinth" problem what I'm running into? If so can a more "standard" prop work in some way, and if not, what do I need to look for to find the right prop?

Thanks all -

 

[Frank Acampora]

Re: 1991 Force 150 prop forward seal question

Not sure exactly what you are referring to however: If you mean the back side of the prop where the hub inserts into the lower unit

Force lower units are smaller in diameter than Mercury lower units. Even though Mercury later changed to Merc designed lowers, the 5 cylinder Force engines always had the smaller diameter. While the splines are the same, Merc props will not fit. SOME aftermarket props (I think Vortex) had a plastic ring which could be removed and the prop hub would then slide into the lower unit.

However, You need to look for thru-hub exhaust props for earlier than 1994 Force engines. Michigan does make a line of stainless and aluminum props. A stainless that will fit is SSC-319-II-C (13 X 19) It also has a Chrysler number of 540 19. If you contact Michigan they can probably tell you the equivalent aluminum model

 

[shushry]

Re: 1991 Force 150 prop forward seal question

Frank -

That seems to be precisely the issue - thanks for clarifying and educating. I do indeed have the 5 cyl Force 150. I'll give Michigan a call to get the right one.

Thanks again

 

[Frank Acampora]

Re: 1991 Force 150 prop forward seal question

You can also use the Vortex 992105 (13 x 19) or whatever pitch in that series you need. However, with that prop it may be necessary to buy a smaller anode or remove the anode from behind the prop. The internal webs will hit some Force anodes. You will think the prop will not fit, but after removal of the anode (and the plastic ring from the prop hub) it will slide on perfectly.