Help! Possibly tore up drive unit.

[Dyna]

Hit a sandbar last week at about 20 mph, bent my prop up pretty good. Got her off the sandbar & made it back to the ramp with no issues. Went to another lake & swapped props for one I had repaired earlier this year. Launched the boat & she idles fine, but try to give it gas & no go, the motor spools up there wasnt any real decent forward movement.<br /><br />My questions are, is there a shear pin I might possibly have snapped or is it possible that perhaps the prop is spinning on its hub? never had an issue with the prop before.<br /><br />Its a 16' 1984 seasprite with a 140hp I/O mercruiser, not sure what drive unit it has.<br /><br />Is it possible I tore up one of the driven gears & if so how much of a pain is it to replace it? Dont have the $$$ for a shop to do the work & I have a long history of repairing my own vehicles, tranny rebuilds, motors, etc.<br /><br />Thanks in advance for any & all help.

 

[Laddies]

Re: Help! Possibly tore up drive unit.

It sounds like the slip clutch in the prop you installed is slipping, when you ck that make sure you have thw right prop hardware installed also--Bob

 

[rodbolt]

Re: Help! Possibly tore up drive unit.

check the replacement prop for a spun hub. <br /> could have damaged the engine coupler as well. usually if any driveline part above the lower case fails engine overheat occurs due to loss of rotation on the seawater pump. but I would check the prop hub first.

 

[TilliamWe]

Re: Help! Possibly tore up drive unit.

Good point Laddies. If it's not the prop, check a couple other things...<br />Does it now overheat? Can you physically see that the splined shaft that sticks in the rear engine coupler is spinning? If it's not turning, you have a spun coupler.<br />If that is turning (which I will bet that it is), then you could have internal problems in the drive. Possibly the vertical drive shaft has sheared off? But experts, would that also cause the impeller to not turn & therefore overheat???<br />The fact that you made it back with "no problems" just after damaging it, says thatyou probably did not suffer gear failure. Cause if you did, it wouldn't have moved once off the sand bar. Then also, if a gear broke on the way back to the ramp, you would have noticed, I think.<br />One last suggestion... do you have physical damage coverage on your insurance policy? Maybe you need to file a claim?

 

[TilliamWe]

Re: Help! Possibly tore up drive unit.

See, rodbolt was answering my question as I was typing it!

 

[Dyna]

Re: Help! Possibly tore up drive unit.

No overheating at all. I trolled around for awhile & the temp stayed at a nice consistent 140 degrees.<br /><br />Is it hard to check the engine coupler?<br />Im going to back the boat into the water after marking the prop & hub, leave it tied to the trailer & just rev her up a bit on the ramp to see if the prop is indeed slipping on its hub.<br /><br />Also yes, the proper hardware was used to install the prop, its the one that was on the boat when I bought it.

 

[Don S]

Re: Help! Possibly tore up drive unit.

Is it possible I tore up one of the driven gears & if so how much of a pain is it to replace it? Dont have the $$$ for a shop to do the work & I have a long history of repairing my own vehicles, tranny rebuilds, motors, etc.

While your problem is either a prop or a coupler going bad, being able to rebuild a drive is not like anything in automotive.<br />All the gear locations and shimming for backlash are set with special tools designed for that special purpose.<br />Others have tried, putting in new gears and such, but it always ends in destroying those expensive new gears and bearings you just put in a few trips ago.

 

[TilliamWe]

Re: Help! Possibly tore up drive unit.

I think I will speak for rodbolt too, when I say, if you don't have any overheat issue, then the coupler should be ok. A coupler is eith good or bad, from what I have learned. And if it's bad, the motor has to be removed to change it.

 

[Dyna]

Re: Help! Possibly tore up drive unit.

Today with everything turned off I put the unit in gear both forward & reverse & attempted to turn the prop by hand, depending on whether it was in forward or reverse it would slip one way..but couldnt budge it by hand in the other direction.<br /><br />So im guessing the prop & drive unit are fine & most likely it is the coupler. Time to dig out the repair manual & see whats all involved.

 

[vipzach]

Re: Help! Possibly tore up drive unit.

I don't think is your coupler. Do you have a set of muffs? If you do then hook them up and start the boat and let ir run for a while, if it never overheats then it is not the coupler. Did you mark the prop and hub and put it in the water yet?

 

[Dyna]

Re: Help! Possibly tore up drive unit.

The repair manual mentions nothing of any coupler. Claims it has an electrically operated clutch setup that drives the drive shaft.

 

[Don S]

Re: Help! Possibly tore up drive unit.

What repair manual do you have? Sure hope your not using some old OMC electic shift manual..........<br />There are no electric clutches in Mercruiser Alpha or pre-Alpha drives. They did have some electric shift mechanisms, but that only operated the shift cable.<br />The coupler is mounted on the flywheel of the engine. It (Basicly) has a rubber insert with metal splines to couple your engine to the outdrive. Even if the rubber was coming loose from the splines, you couldn't turn it by hand at the drive, and yes, you can turn it one way but not the other. That is quite normal.

 

[Bondo]

Re: Help! Possibly tore up drive unit.

Originally posted by Dyna:<br /> The repair manual Claims it has an electrically operated clutch setup that drives the drive shaft.

Not if you've got a,<br />

16' 1984 seasprite with a 140hp I/O mercruiser

That'll be an Alpha1, or Pre-alpha,.......... Nothing Electrical about those drives.........<br />All Mercruisers have some sort of Engine Coupler........... <br /><br />Let me Guess,............ Seloc,.. or Clymers,..???...... <br />If it's an Internal Drive Issue,....... You'll be needing a Factory Mercruiser Shop Manual............<br /><br />Good Luck........

 

[Dyna]

Re: Help! Possibly tore up drive unit.

Could the solution really be this simple?<br /><br />I spent some time examining the coupler...I can see it & it appears fine. However I decided to take a closer look at my props...both of them. The one that came with the boat was a 14/21 & the replacement was also the same. The one that came with the boat I had sent out for repair but upon closer inspection its not my prop. I know this is going to sound crazy but I really didnt examine it all the closely when I got it back & mine had no markings on it when I sent it out however this one is clearly stamped as a 14/11 on the hub.<br /><br />I believe that is the entire source of my speed issues. Now I just have to convinve the marina they gave me the wrong prop 2 months ago.

 

[Phantom17]

Re: Help! Possibly tore up drive unit.

If he got back to the ramp with a destroyed prop OK, and the engine didn't overheat, or slip like a spun prop, why are we ripping the engine out to check the coupler? The problem sounds like the new prop. <br /><br />How high max RPM did you go back to the ramp at?<br /><br />How bad was the prop? Did it vibrate like a *******, or go OK?<br /><br />....first thing I learned, nothing that works OK on muffs means it really works.<br /><br />Good luck, hope you found your problem. You can let the experts do the prop math for you, thats like speaking Latin to me.

 

[Dyna]

Re: Help! Possibly tore up drive unit.

Originally posted by jh19:<br /> If he got back to the ramp with a destroyed prop OK, and the engine didn't overheat, or slip like a spun prop, why are we ripping the engine out to check the coupler?

Didnt need to pull the motor to see the coupler, was able to remove the covers & could see the input shaft for the stern drive unit, was able to stick a dental mirror down & visually inspect the coupler & its fine...definitely a prop screw up.

 

[Phantom17]

Re: Help! Possibly tore up drive unit.

Luckily for him. Just wondered how we got to coupler.