How much Prop Play and Gear Noise is normal rotating freely? for Alpha 1 Drive

moritz55

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Jul 20, 2012
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I have a 1984 Dixie Boat Works Super Skier 199 with a 260HP Small Block Chevy V8 Mercuriser, Thunderbolt IV ignition and an Alpha 1 drive. Engine sn: 06840683 and the Outdrive (is hard to read) SN: 0314065 or 3314065 . Total hours on the engine is 410 hrs. I bought it with 320hrs 2 seasons ago and it's a fresh water boat in North Carolina.

Background:
Engine and outdrive run great. The outdrive was rebuilt 3yrs ago 1 month after I bought it as a result of fishing line in the outdrive and the oil leaked out. This was from the prior owner who traded it in. Since I bought this from reputable boat dealer who I know personally, they rebuilt the entire outdrive with Mercruiser parts - $2100 for the entire job and I got a very good deal costing me only $700 in labor.
Since then .. No oil leaks, no noises of any kind while idling or running WOT and shifting is clean and quick. It really runs sweet and I've been able to get 57 mph at 4300 RPM which is close to spec given I have a 4 blade prop for better hole shot (spec is 60mph @ 4400 rpm). I have had the boat now entering 3 years and have had it serviced professionally in the fall as I watch while they change the outdrive oil, lube the prop, replace the impeller, drain the water and fog the engine - all this goes well.

My questions are purely of learning and also preventative in nature:
Q1) My prop has some play in/out and would like to know what's normal . I have read about 1/8" seems normal so would like to confirm is this normal for an older 84 Alpha I outdrive?

Q2) When I freely spin my prop there is a gear rotating and meshing noise. Not at all a grinding noise but it is loud enough to be noticeable as the gears freely rotate with the prop. It's not the thrust bearing or anything with the prop hub - that's all normal and secure to 55ftlbs. Is this noise normal for an older Alpha I ?

Q3) The gear noise essentially disappears when I freely spin the prop when it's pulled away from the outdrive (when the play is such that it's pulled out while spinning). Is this normal for an Alpha I?

When I freely spin other outdrives on boats that are stored near mine - they seem to have slightly less or no play but not the gear noise, mine is more noticeable than the others. These are all newer boats both outboards and I/O Mercruisers or Volvo Pentas.

Any insight or advice is welcome.

Many thanks .. Mark
 

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JustJason

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Re: How much Prop Play and Gear Noise is normal rotating freely? for Alpha 1 Drive

1. That's about right.

2. More than likely what your hearing is the clutch dog bouncing around in there, and bouncing off the gears. When you spin the prop shaft your not actually spinning the gears. What you are spinning is the the propshaft, the clutch, and a couple of bearings in the rear bearing carrier.

3. More than likely it's again just the clutch your hearing. Again when you spin the propshaft like that, your not actually spinning the gears. They are not moving.
 

moritz55

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Re: How much Prop Play and Gear Noise is normal rotating freely? for Alpha 1 Drive

Many thanks JustJason for such a quick response. I feel much better and did not realize the gears in the lower unit are not actually engaged when it's in neutral.

Thanks again !
Mark
 

Bondo

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Re: How much Prop Play and Gear Noise is normal rotating freely? for Alpha 1 Drive

Many thanks JustJason for such a quick response. I feel much better and did not realize the gears in the lower unit are not actually engaged when it's in neutral.

Thanks again !
Mark

Ayuh,.... Welcome Aboard,.... I agree with Jason, sounds pretty normal to me,...

The 2 big gears on the prop shaft spin with the prop shaft,....
When ya shift into gear, the slidin' clutch picks up 1 of the 2 gears, to go the direction ya want,....
All 3 gears are actually in full mesh, 100% of the time,... so some "gear noise" is expected,...
 
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