Prop + Rock = No Transmission

[swiftsam]

Hi All,

You were really helpful the last time I got myself into a problem, but I think I've got myself a bigger one this time.

Boat : 1984 16' Four Winns Marquise 160
Engine : Mercruiser 4-Cylinder 140 I/O

I was going 75% power (prob 25mph) when I hit a rock or something with the prop. Heard a bad but brief sound of prop on rock, and then it was as if I was in neutral, but with the engine still running at 3k rpm. Turned it off right away and put the outdrive all the way up. All three prop blades are dinged, one pretty badly.

Engine still starts and runs fine, but it doesn't even try to go into gear, forward or reverse.

So my question for those with more experience is what is likely to be broken in the Engine --> transmision --> outdrive --> prop linkages and how badly. I'll be starting tomorrow morning looking to figure it out myself and/or finding a shop to take it to. If anyone has experience or advice on this type of damage, I'd love to hear it.

Thanks!

 

[Bt Doctur]

Re: Prop + Rock = No Transmission

Check to see if it`s overheating Yes, could be coupler is bad, the lower unit driveshaft snapped at the very top where it goes into the upper housing.
No, driveshaft snapped just below the water pump, pinion gear sheared off in lower unit.You may have to split the drive to narrow it down.

 

[BAYLINER185]

Re: Prop + Rock = No Transmission

does your shift handle shift or is it frozen in place?

You may need a new clutch in the lower unit!

 

[Don S]

Re: Prop + Rock = No Transmission

Equal chance that it's a prop, drive, or coupler issue.

We could probably vote on it, but the only way you will find out for sure is to start testing.

Without the engine running, put it in forward. By hand, turn the prop CCW, it should catch. Does it? or does the prop shaft catch and the prop move?????

 

[maxxman04]

Re: Prop + Rock = No Transmission

if engine stills runs, you can rule that out. then it becomes a matter of hunting. ideas: broken lower shift cable or out of whack now, broken lower shaft, broken intermediate shift shaft. basically start with simple.

 

[swiftsam]

Re: Prop + Rock = No Transmission

does your shift handle shift or is it frozen in place?

You may need a new clutch in the lower unit!

You guys are great, thanks for all the quick responses.

The handle moves fine, and all the clutch / transmission linkages that you can see in the engine compartment look fine and move well.

 

[Don S]

Re: Prop + Rock = No Transmission

if engine stills runs, you can rule that out. then it becomes a matter of hunting. ideas: broken lower shift cable or out of whack now, broken lower shaft, broken intermediate shift shaft. basically start with simple.

If you hit a rock, you aren't going to break a shift shaft or a shift cable. And trust me, engines will run with broken gears and shafts in the outdrive, along with broken couplers and props

 

[Bt Doctur]

Re: Prop + Rock = No Transmission

might want to check your prop shaft too.There was a SS Hi-Five on this motor that was reduced to the size of a grapefruit.They were going a lot faster and hit a much bigger boulder.Exploded the lower gear case, literally.Tore the crankshaft end off the crankshaft (Black Max O/B)

 

[swiftsam]

Re: Prop + Rock = No Transmission

Equal chance that it's a prop, drive, or coupler issue.

We could probably vote on it, but the only way you will find out for sure is to start testing.

Without the engine running, put it in forward. By hand, turn the prop CCW, it should catch. Does it? or does the prop shaft catch and the prop move?????

The boat was still tied up this morning where I left it on the river last night, so I'm off to a good start.

I got it out of the water and it looks like all of the local mechanics have a multiple-week waiting list right now, so I'm delving in myself. I've got my manual out and am figuring out what's what.

To answer the diagnostic question above, if I put it in forward gear with the engine off, the prop spins freely clockwise, but catches and stops CCW. What did that rule out?

Thanks!

 

[bruceb58]

Re: Prop + Rock = No Transmission

Lower gears.

Put a spare prop on and try it out. Then you can rule out the prop.

Was this an aluminum or stainless prop? If it was aluminum, you are more than likely going to be fine and it will just be the prop.

 

[swiftsam]

Re: Prop + Rock = No Transmission

I called all the mechanics in the area and the very few that bothered to call back said it would be 3 weeks or more before they could take a look at it. So I'm on my own. Thanks for your help so far.

I've got the '84 Alpha 1 outdrive removed from the boat. I've got the prop (which is stainless unfortunately) removed from the outdrive. I've got the upper and lower halves of the outdrive separated. So far I haven't been able to see anything that is obviously broken. None of the visible shafts are broken, and none of the grooved ends look stripped out at all.

In trying to narrow down the culprit, we did some tests:

• Lower Unit : If you spin the prop shaft with the shift shaft rotated to one side or the other, the drive shaft spins. It also works the other way (spinning the drive shaft turns the prop shaft
• Upper Unit : If you spin the long yoke, and look up into the bottom of the upper unit you can see the bottom of the upper drive shaft spinning

What I can't understand is how the Lower Drive Shaft connects to the Upper Drive shaft that I can barely see. I'm wondering if that's where something broke and might even be missing now.

I've been using two parts diagrams from sterndrive (upper and lower) to try and understand how they
are supposed to connect. So far I don't get it.

So my questions are:

• Does something look wrong in the connection from the upper to lower drive shafts?
• If not, does any of what I've got so far point to a different failure point?
• If not, what should I take apart next

Below are three pictures to hopefully make it clearer what I'm talking about.

 

[FreeBeeTony]

Re: Prop + Rock = No Transmission

That's your problem..........the top of the driveshaft sheared off from the lower unit and is still in the upper gears..........

 

[swiftsam]

Re: Prop + Rock = No Transmission

Thanks for clearing that up. I knew something looked wrong, but having never seen it correctly assembled, I didn't know what I was looking at. I guess I expected the break to be more ragged.

Of course, the next set of questions that hit me are about getting a new drive shaft in there. I've made it this far, but I'm wondering if getting that shaft out of the lower and upper units is getting a bit too complicated for the garage.

Do you need any specialized tools to pull the shaft out from the lower unit?

Thanks again to everyone who has pitched in here

 

[swiftsam]

Re: Prop + Rock = No Transmission

... the lower unit driveshaft snapped at the very top where it goes into the upper housing ...

oh, and by the way, credit to Bt Doctur for the super fast and impressively accurate response to my original question. You nailed it.

 

[Bt Doctur]

Re: Prop + Rock = No Transmission

Just tell me how you accessed my photo library?
I had the same pics of the same result.
Your splined section sheared off in the upper gear.Check with your insurance to see if they cover submerged obstructions and check the SEI drives out. Complete unit for under $1200.00
www.sterndrive.cc

 

[bigskiohio]

Re: Prop + Rock = No Transmission

My brother in law did that and insurance paid for it, so check if you have coverage.

 

[swiftsam]

Re: Prop + Rock = No Transmission

Thanks to all of you guys for telling me what I was looking at. I ended up going with a new complete outdrive unit from SEI. It wasn't cheap (at least compared to my very affordable boat), but getting it on the boat was relatively easy, and I was back in the water 9 days after I hit the rock. Being back on the river for the 4th was worth it.

Thanks again.

I think I'm going to try and sell my old outdrive for parts. My instinct is that I'll get more for it if I disassemble everything and sell the parts individually on ebay or something. If anyone has any experience or input on that plan, I'd love to hear it.