Prop rubbing housing

harleyman_nc

Recruit
Joined
Jun 9, 2008
Messages
1
I just purchased a 1995 1800 Bayliner with a 120 Force on it, this boat has set for a couple of years. The boat registation ran out in 06. Took it out this weekend for a test run. Everything was going well for a couple of hours I ran the boat at different speeds and was basiclly getting a feel of how the boat would handle. We where running along at top speed when the engine started reving as though it had no load, I stop and raised the engine, the prop was rubbing the side of the lower unit. Brought the boat home, pulled the prop and the hub was detiorated, I suspected that it was because of age. Anyway, got a new prop and installed it tonight however when I spin this prop it is still rubbing the housing slightly. I pulled the prop back off and put a dail indicator on the prop shaft a can move the shaft up and down a couple of degrees and when I turn the shaft it is not true.
Should there be this much play in the shaft? The prop that was on it was a 12 3/4" X 23 pitch, I have been looking at the post and most are running 17 or 19 pitch
Could the wrong prop cause this rubbing?
Also, how do I know if I have a L drive?
 

maxum247

Lieutenant
Joined
Sep 18, 2007
Messages
1,363
Re: Prop rubbing housing

An L-Drive is an outboard powerhead mounted inside the hull with the outdrive on the outside of the hull.
If the motor hangs off the stern its an outboard.
Reason I mention this is because you mention it has a (120 on it.)
Although there was a 120 L-Drive produced.
 

maxum247

Lieutenant
Joined
Sep 18, 2007
Messages
1,363
Re: Prop rubbing housing

What rpm were you running at full throttle with the 12 3/4"x23?

In reference to the prop rubbing the housing, when you removed the prop was there a splined washer behind the prop about 2" in diameter and about 1/4" thick?
Has to be there on my 89 125 Force or the prop will rub.
My 89 125 Force has about the amount of play in prop shaft as yours and my engine has very low hours on it.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Prop rubbing housing

The outboard lower unit should have .010 end play in the prop shaft. If you grab it by hand then push in and pull out you should be able to feel and possibly hear a slight click. because of the design of the gearbox, more than .010 will not hurt anything if it is not excessive --like 1/16 or more. I would not be surprised if the L-Drive had similar tolerances.

The splines on the prop shaft only go partway down and if you do not have a thrust washer behind the prop, it will rub on the gearcase until the ends of the splines stop backward movement. This can be different for different brands of props. Thus, until you spun the rubber hub in the old prop, it did not contact the gearcase.

Obviously, the new prop will not have its outer hub worn, so it will contact the gearcase when installed without a thrust washer.
 
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