2005 suzuki df250 lower unit malfunction with only 400 hrs. of use

[HAWK556]

Recently, on my return from Bimini (32 miles offshore) I stopped the boat, placed the engine in neutral, waited approximately 15 minutes (drink and sandwich) and shifted the engine back into forward gear (had audible engagement along with forward propulsion) as I went to accelerate the engine went into a high rev coupled with the sound of broken internal linkage (the sound of metal components being bounced around). I immediately shut the engine down. I waited 30 seconds and restarted the motor which was followed by the sound of a broken gear/linkage inside the lower unit. I was unable to place the engine back into gear. Engine was again shut down and left off. Fortunately, I have twins and was able to return to port (32 miles from shore) on one engine. I believe that hard floating debris may have locked the prop up temporarily (but should have spun a hub). Once back on land I briefly inspected the lower unit by free spinning the prop. When I did this it seemed like it was spinning too freely, as if not connected to anything internally......I also compared this spinning to the operable engine's lower unit and there was significant difference in the feel. I was curious if anyone else has had any issues with there lower unit malfunctioning the same way? I also noted that on the suzuki specs page for this engine it states under "drive protection" that it has a spline drive rubber hub. Is it possible that this is just a rubber hub inside the lower unit that went out (hopefully not as costly)? Back at home I drained some of the lower unit fluid to inspect for possible water infiltration and/or metal fragments with none found. I have already dropped this lower unit off to my mechanic who will in turn ship this to a lower unit rebuild mechanic but I would like to find out if anyone has any information on this subject. Thanks.

P.S. The motor/lower unit has been service annually with the water pump and thermostats just recently being replaced...I did notice that when I replaced the water pump on that lower unit the drive shaft splines had what appeared to be hardened grease inside the grooves of the splines, there was also some spline wear (minor damage you might see from hard shifting....splines were cleaned with no heavy damage noted, no internal components (lower unit) were touched.

 

[Art Bernard]

Re: 2005 suzuki df250 lower unit malfunction with only 400 hrs. of use

Man, if your hearing metal clunking around in there it's a good bet your gears are trashed. The other thing your talking about if I understand correctly is the rubber insert in your prop. It's purpose is to waste itself before it wastes your prop or gears. I wasted one of these once and the result was a suden and drastic rise in the rpm. I noticed it immediatly and went to neutral, but I guess it's possible that it could way over rev causing gear damage. Anyhow, that getting wasted does not make metal crunching noises.

Art

 

[HAWK556]

Re: 2005 suzuki df250 lower unit malfunction with only 400 hrs. of use

just received update from mechanic that lower unit is 10-8, upon further inspection I have found that the internal splines have been completely destroyed. never heard of this happening. does anyone know just what the driveshaft connects to inside the motor.....is it the crankshaft? do i have to split the block to get to this piece? I was always under the understanding that the hub and driveshaft are suppose to fail before anything in the motor fails. I will also be contacting suzuki!

 

[Silvertip]

Re: 2005 suzuki df250 lower unit malfunction with only 400 hrs. of use

Here's the path for power delivery. The drive shaft is a vertical shaft that runs the length of engine from the bottom of the power head and extends into the lower unit. Splines on the top of the shaft mesh with splines in the crankshaft on the engine. A bevel gear in the lower unit at the end of the drive shaft meshes with another gear placed horizontally in the lower unit. This is the shaft on which the prop is installed. Spline drive simply means the prop end of the shaft has splines that drive a metal hub. The metal hub has a rubber cushion bonded to it and the blade area of the prop. when striking something, that bond between the rubber is intended to fail thus sacrificing itself. Since something has broken inside the lower unit, I suspect either the pinion (end of the vertical drive shaft) gear and/or its mating prop shaft gear have failed -- hence the disconnect. Idle speed set too high can cause gear failure when shifting. Or -- stuff just happens and parts break. It shouldn't happen but it does. Lastly, the prop shaft may have broken but I doubt that as you said the prop turns freely. It would wobble and likely grind even when turned by hand. No -- you don't need to open up the engine to fix this unless the splines at the top of the vertical drive shaft or those inside the crankshaft were damaged. I doubt that's the case.

 

[clanton]

Re: 2005 suzuki df250 lower unit malfunction with only 400 hrs. of use

The driveshaft is driven by gear off set from the crankshaft. Driveshaft splines are inside this gear. This gear rides on a ball bearing, and there have been failures of the bearing. You have to remove the powerhead to repair this.

 

[99yam40]

nope,prop hub spun is most likely

do not post on old threads, start a new one for you motor an problem