290 DP Prop Cone/Nut Torque

[Horigan]

I had an issue earlier this year where I lost a rear prop on one of my 290 DP drives due to apparent insufficient torque on the prop cone and center bolt. I had used a Volvo prop removal/install tool and thought I had pretty good torque on the cone and center bolt. I acquired another rear prop and a used cone with center bolt. This particular center bolt took a 12mm socket to tighten. (The other side has a 13mm socket bolt.) During prop installation from the swim deck (boat in the slip) I felt the 12mm socket slip during torquing. I assumed I had rounded the bolt head corners and ordered a 13mm head center bolt for the next anode change. I did that anode change yesterday and discovered that I had actually sheared off the center bolt. It is flush with the end of the inner/rear prop shaft.

A couple of questions:

What approximate torque are people using to install the rear prop, both for the cone and the center bolt? I see little reference to prop nut torque in the 290 manual, except where it describes drilling the center shaft using the tool referenced below and torquing the cone on to 81 ft-lbs (center bolt 16 ft-lbs). That torque level isn't really possible with the short Volvo prop tool.

I see there is a Volvo tool 885149 that's a drill jig to drill a hole down the center of single prop 290 drive shaft to enable the installation of the center bolt. Does anyone know if this tool will work on the inner/rear prop shaft of a 290 DP? I was going to fashion my own tool to drill and remove the sheared bolt, but this tool may be easier.

 

[Scott Danforth]

The torque on the lock bolt is only about 15 ft-lb

You could get a deep-well 12-pt socket to sit over shaft, and use as guide for drilling. I would use a left-hand drill

 

[Horigan]

Thanks. Good idea on the socket. I intend to use a left hand drill. I'm hoping it comes out easily when I haul the boat out this spring...

 

[Scott Danforth]

Thanks. Good idea on the socket. I intend to use a left hand drill. I'm hoping it comes out easily when I haul the boat out this spring...

use Permatex #3 on the screw going forward, wont ever bind

I have 4 different nuts from over the years. have 3 different styles of lock screws. some of the cone nuts got damaged when I lost a prop hub hear and there, repaired those.

 

[Horigan]

Good idea. I was thinking a thread lock, but not sure about underwater use.

 

[Scott Danforth]

Here is how I torque the prop nuts for the past 11+ years on my 290DP

clean the shaft splines with brake cleaner
clean the prop splines with brake cleaner
clean the nuts with brake cleaner
grease shafts with VP shaft grease (blue stuff in the really pricy tube)
grease nut threads

front prop, shove a chunk of 2x4 between drive and prop. use channel lock to hand tighten the lock nut, bend the tab. Insert line cutter

aft prop, install exactly 180 degrees out from front prop. Move block of wood to between the prop and the drive. spin on prop nut, shove screw driver thru hole or slot and turn with a grunt.

tighten lock bolt with wrist on head of ratchet.

long ago jetisoned the plastic washers that kept breaking. made aluminum versions that just got damaged by salt. water jet a few garolite washers. sometimes I use them, most of the times I dont.

I do swap props about 2-3 times a year as I am boating in some skinny water. Moeler etching primer and a can of black rustoleum makes the props look good again for a few months.

never lost a nut, or broke a lock bolt. have spun about 5 props and the folks at General Propeller know me on a first name basis.

On board, I have a spare prop set, spare prop hardware and a simple tool box.

also have the Tow Boat US membership for when you shear off both prop hubs and a few blades and plug the raw water pickup from the drive to the crank mounted pump with muck because the channel moved from the prior day and you ran the drive into the muck

 

[QBhoy]

Amazingly, this very thing has happened to 3 people I know locally here. I also think that very often people forget that there is a retaining bolt in the nose cone. Common to break them it seems. I used to put a screw driver through the holes on the nose cone to tighten it up. Then tighten the retaining bolt after. Reverse procedure for removing obviously.
Very important to clean and grease the splines and all surfaces each time the props are assembled. Making sure they are home and positioned correctly and all tightly fitting. Alternatively you’re tightening up against dirt and crap..usually meaning they are lacking secure taught assembly.

 

[Horigan]

Yeah, I think I didn't have the shaft cleaned enough when I lost the prop and thus tightened against some crud. Thanks for the insight and detailed procedure. I'll find a longer large rod or screw driver so I can attain a higher torque on the cone.

 

[Horigan]

I've been noddling how I'm going to drill out the center of this broken center bolt with a left hand drill bit and I discovered a cool tool to keep the drill centered, a hinged sighting drill. The end of the prop shaft has an internal taper, so this should work pretty well. Thought I'd share for those that run into a similar situation. Still waiting for spring haul out to do the removal, but at least now I can stop looking at broken bolt removal videos on YouTube.