Prop Problems

tejohnsrude · Posted: Tue Oct 21, 2008 3:43 pm Post subject: Prop Problems

I have been having serious problems with prop failures. After about 50 hours they begin to free-wheel (engines race without cause). My mechanic tells me that this a a prop failure and not an engine problem. I do not do jack-rabbit starts, nor have I hit anything My prop-guy said that the wrong props were installed originally so different ones recommended with different pitch and different inserts between prop shaft and the actual prop. STILL NO BETTER. I have installed FIVE props in 2 Honda 40 HP outboards in a period of 18 months. Anyone else with this problem? Any insights?

Ted

Captains Cat · Posted: Tue Oct 21, 2008 3:56 pm Post subject:

This is undoubtably a "spun prop". If you search on that term, you'll find some hits. There's a rubber bushing between the drive shaft and the innards of the prop that is supposed to be a vibration/surge damper, I think. If you have hard/bad rubber or over torque it, the rubber can break down and the prop will spin loosely.

It's either indicative of a bad prop (the rubber is faulty in some way and failed) or over torqueing causing the rubber to fail. I had two Honda 45's on a 22 Cruiser for years and never a spun prop.

Thank heavens, a boat and not a political post. (unless the Democrats caused it! Shocked

)

Charlie

Sea Wolf · Posted: Tue Oct 21, 2008 4:28 pm Post subject:

I was told by the counterperson at Pitch-O-Meter Propeller Service in Alameda, Ca, that the rubber bushings and hubs were presed into the props using a hydraulic press with Kayro Syrup as a lubricant.

My guess is that the sweet syrup dissolves out later with water and time, and/or sets up hard until the prop is eventually immersed in water.

Sounds feasible, enough, huh? Wouldn't want to use a petroleum product on a rubber bushing......

Joe. Teeth

thataway · Posted: Tue Oct 21, 2008 5:57 pm Post subject:

There has to be something wrong. I have only spun two outboard props in over 50 years of owning outboards which had the pressed in hubs.

Bad Boy · Posted: Tue Oct 21, 2008 6:48 pm Post subject:

What diameter and pitch are you turning?

marvin4239 · Posted: Tue Oct 21, 2008 7:20 pm Post subject:

Are you maybe over torquing the prop nut?

Wandering Sagebrush · Posted: Tue Oct 21, 2008 7:37 pm Post subject: Torque on Prop Nut

Marvin,

I did not know that there was a specific Torque on the prop nut. Then again, I have never read the manual on changing the prop, I just did it.

Can you provide more info...

Steve

marvin4239 · Posted: Tue Oct 21, 2008 8:35 pm Post subject:

Steve I don't presently have a Honda but I did have a Honda 50 for about 9 months. If I remember correctly the manual called for a very low torque on the prop nut maybe 15 lbs as opposed to my Suzuki which calls for 45 lbs torque. If you have the owners manual I'd check the torque value.

marvin4239 · Posted: Tue Oct 21, 2008 9:24 pm Post subject:

http://www.honda-marine.com/mar_pdf/31ZW4600.pdf

Steve heres a link to the Honda prop install. It doesn't say to torque the nut at all just to hand tighten it. Then just tighten enough for the carter pin hole to be aligned.