JON242

Yesterday I was running at WOT when I picked up a vibration, speed started to drop and I think RPMs started to go up. The reason I say "I think" is that I quickly throttled back and in thinking about it later I'm not 100% sure that the r's went up. I opened the hatch, checked everything out, and ran it back in to the marina at 3000 rpm and it seemed fine. I didn't want to push it and end up getting towed in. Here are my questions. My initial thought was a spun prop hub. If that was the case could I tell by looking at the prop. It is a Ballistic which I think has a pressed in hub. Second thought was that something happened to the coupler. It is a 3 finger type. Could I have a problem with it that wouldn't show up until WOT? Could either of these situations cause a vibration? In thinking back it could have been a miss but the engine idled and ran fine afterward. I know it's not alot of information to go on here but any ideas on where to look?

mopower

Well Jon,
If you were on the Delaware like I suspect , you sure you didn't just snag something. I've done it many times and the symptoms are the same .
Rpms go up and speed goes down . I guess you didn't try stopping and backing up a bit to clear the crap off? If you look at the prop closely and see bits of balled up rubber hanging out of the hub , it's probably spun . Couplers usually just flat out go and you don't! Been there done that . My bet is you had something on the outdrive . if you were in the trash can Delaware.

Offshore Addiction

hes right about the traces of rubber,look on the front of the wheel by the thrust washer,if your still in question you should have a local prop shop that can test the hub,it should hold about 750 ft lbs of torque....you can also reach behind the engine and feel around the coupler.....but they usually go out and you don't(nice wording)also inspect the magnets on your drive as you may be spittin parts......our hillsboruogh river is also notorious for the trash,all the streets run off into it,a plastic bag will cause it to cavitate and loose speed and gain r's

formula31

In my experience, if the prop hubs spins loose, it wont hold much over idle, around 1000 rpm, then spins loose again. But that was with Merc props. If the engine coupler goes, its usually much more dramatic and noticable. Let us know, I still have the triangular couplers too and Im sweating them. How much power do you have?

cuda

If it was the coupler, there would be no doubt in your mind. The engine compartment would fill with black rubber smoke. I was afraid to lift the engine hatch until I had the extinguisher in my hand.

mopower

Cuda's right if the rubber goes. On mine the aluminum splines gave way ( alignment problem). No smoke , no smell. After I fixed it , that motor was 3/4 inch higher than the other . Yeah you guessed it . Aligned that one too , before it was too late

HOUSTONPROP

you all are correct , here is one other way you can check the hub and that is to take the prop off take a center punch and mark the inner hub if the PROP and then come straight across and mark the brass or aluminum center of the hub, then put the propeller back on run it again and pull it back off to see if the marks are Lined up if not its slipping, oh if its a stainless prop it should have a brass and rubber hub as the durmonter is higher than a prop with aluminum and rubber that is usually for a aluminum prop . hope this helps.

JON242

Thanks for all the replies. MOPOWER - Yes, I was on the river. I keep my boat at Hargrove's. Beautiful day but more trash than I've seen all year. After it happened I stopped the boat and raised the drive. Didn't see anything but it might have floated away by then. I hope that's all it was.
Formula31 - I'm running about 425hp through the triangular coupler. I've been running this hp for about 4 years and stock hp for quite a few years before that and no problems but I do baby it since I'm running an Alpha.

formula31

Thanks, I plan on replacing mine but its pretty low on the money list right now.

HOUSTONPROP

they are very inexpensive normally around 55.00 installed.