Outboard pros - Prop Spin whilst in Neutral

heywillhay1, Nov 4, 7:30pm
Hey Fellas,

Bought a new rig last weekend with a 97 60hp Mariner 2stroke, noticed the prop spinning while in neutral while I was running it up, at a guess I'd say it was doing about 150-180rpm in reverse. Felt for any movement or grinding when I stopped it but was all ok.

Anyway got it home and did a gearbox oil change and took the prop off, cleaned shaft and relubed, ran it up again and it probably halved the spin speed. Took it for a sea test and all was ok (although I completely forgot to check if it was spinning whilst in water).

Im just wondering if there's anything I should be concerned about? My old 30 didnt spin nor did a mates 96 90hp Merc. I've read conflicting thins about it so thought I'd try here too

Cheers

aj.2., Nov 4, 7:41pm
just that every thing is new , the shaft is turning , but is pushing the oil around, so is causing a flow, and the prop is turning backwards because of it.
But if you start it , and hold the prop with a piece of wood , it will not try to turn .
You would have not have felt it trying to push , at the sea test , as it is not being Gear driven , at that stage.

heywillhay1, Nov 4, 8:25pm
Thanks Aj, yeah when it was running I was able to stop the prop with my boot and I couldn't feel any resistance to this so I assumed it was all ok. Just that it was spinning so quick worried me, I thought it may be going backward in the water!

m16d, Nov 5, 5:25am
Thats a Mariner for you. I followed one on a trailer once and the prop was spinning about a million revs in the wind.

bwg11, Nov 5, 6:19am
Both my motors spin the prop slowly (about 100 rpm) when flushing with muffs. Mercury and Yamaha.

klrider, Nov 5, 6:34am
You have to be very very careful, my previous 90 hp Yamaha was spinning in a similar fashion, it took off and flew into the next neighbourhood, lucky it didnt hurt anyone.

heywillhay1, Nov 5, 10:41am
Thanks Guys, Doesn't sound too harmful then, bit of a follow up question, will it cause damage to put it in gear when flushing the outboard on the driveway?

bwg11, Nov 5, 2:43pm
No, that is provided the prop doesn't catch on the hose !

snork28, Nov 5, 5:02pm
my 50 hp merc has done that since ive owned it about 6 years, i just put a piece of wood under it when flushing to stop prop turning,the prop wont turn when in the water theres to much resistance.

gamefisher, Nov 5, 5:03pm
This may help to understand how an outboard gearbox works. https://www.youtube.com/watch?v=cCKM99k1NsU

heywillhay1, Nov 5, 6:11pm
Wow the gearbox is quite simple!, thanks for sharing Gamefisher, nice point about prop freewheeling on the trailer. I can say I've ever put it in gear but then again I have a flag around the prop when on the trailer

mainlander05, Nov 11, 7:15pm
Sometimes its best to keep mouth shut when talking BS as it dribbles down your chin.
You must be the idiot of the day in here.
Normally I wouldn't even bother with dipsticks like you but seriously?