Elec Shift- Spring/Magnet Issue or Prop Slip?

[KRH1326]

Hi All,

Found a whole new problem to work on.

I was running through rough chop, 2-3' chop , at approx 3100-3200 RPM. Out of the blue, I lost forward thrust, and the engine rev'd out to above 5000 RPM, and I instantly dropped throttle and slipped nuetral.

I poked around and couldn't find anything amiss. I hit forward and started to move. As, I tried to throttle up, I wasn't getting any more forward thrust, but RPMs started climbing freely. I completely shut down.

I ( with engine not running) slipped forward gear, went to prop and turned by hand. It locked up OK in one direction and turned the other way with what felt like spring resistance. Tried the same for Reverse. It locked up the other way and turned the other with the same kind of springlike resistance.

As far out as I was, and the fact that I had two of my small children with me, I decided to just put back to the bay, back to the harbor, back to mooring and get the kids on firm ground.

I was able to make it at 1000 RPM's and NO MORE. Any higher RPM resulted in climbing RPMs.

I understand how the Electric shift works, and have been EXTREMELY anal about only shifting below 500-600 RPMs. I have not strained this system whatsoever.

If I wrecked the shifting mechanism, I don't know why I still had forward and reverse at and below 1000 rpm. Is there a clutch incorporated in the prop? I know that my little outboards always had shear pins, do these large props on upper HP drives have some sort of protection?

I have never had any type of electrical issue with this boat, and do not have issues with losing power, intermittant power or anything like that.

OK OMC guys, where do I start looking?

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Hi All,

Found a whole new problem to work on.

I was running through rough chop, 2-3' chop , at approx 3100-3200 RPM. Out of the blue, I lost forward thrust, and the engine rev'd out to above 5000 RPM, and I instantly dropped throttle and slipped nuetral.

I poked around and couldn't find anything amiss. I hit forward and started to move. As, I tried to throttle up, I wasn't getting any more forward thrust, but RPMs started climbing freely. I completely shut down.

I ( with engine not running) slipped forward gear, went to prop and turned by hand. It locked up OK in one direction and turned the other way with what felt like spring resistance. Tried the same for Reverse. It locked up the other way and turned the other with the same kind of springlike resistance.

As far out as I was, and the fact that I had two of my small children with me, I decided to just put back to the bay, back to the harbor, back to mooring and get the kids on firm ground.

I was able to make it at 1000 RPM's and NO MORE. Any higher RPM resulted in climbing RPMs.

I understand how the Electric shift works, and have been EXTREMELY anal about only shifting below 500-600 RPMs. I have not strained this system whatsoever.

If I wrecked the shifting mechanism, I don't know why I still had forward and reverse at and below 1000 rpm. Is there a clutch incorporated in the prop? I know that my little outboards always had shear pins, do these large props on upper HP drives have some sort of protection?

I have never had any type of electrical issue with this boat, and do not have issues with losing power, intermittant power or anything like that.

OK OMC guys, where do I start looking?

You sure you didn't just spin the prop in it's hub?? I had a similar experience with my Bayliner. I hit the throttle and she leaped but then sudden lost thrust and rpms went to 6000 and sucked the carb dry (thank god) and she died. When I restarted I could only get about 1000 rpms or less. It was enough to idle home with some forward thrust but anything more and it would just spin in the hub. I had a new hub installed in the prop and she was fine after that.

Just a thought.....

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

That is , I guess, part of what I am asking. How do I know if there is a hub/ prop issue and how to diagnose it?

Thanks for your quick answer.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I'd pull the prop and look closely at the rubber center and see if you can see any irregularities in the rubber . It should be smooth but if it's spun, you might see what looks like a crack around the center.

You could remove it and lock it into a vice but honestly not sure how much physical strength it would take to turn it by hand.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I should clarify....and forgive me if I'm telling you something you're already aware of......

The center of the prop is a big rubber plug with a shaft glued through the center of it. The plug and shaft can only be installed via a machine which compress the rubber plug. The tension of the expanding rubber locks the plug to the prop. When you spin the prop, the rubber inside usually shears away from the center shaft allowing it to spin. When you slow it down, the tension is sufficient to allow some forward rotation but too much RPM's will overcome the tension and allow the drive shaft to spin again.

If your outdrive were the source of the problem, you'd likely not get any forward RPM's and you'd be hearing a lot of noise coming from it.

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I have a spare prop in the garage, and just looked at it again. I do not see any rubber at all. All seems to be metal. It looks like the "hub" that the shaft passes through is just pressed into prop, like I said no rubber showing.

I am still learning, so please feel free to be as explicit as you want.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

While you might see metal, I'm pretty sure the core is rubber. I could be wrong but I just bought a refurbished prop for my electric stringer and they inadvertently put the wrong kind of shaft in it so it wouldn't fit. They had to remove the core and install a new one with the right shaft.

Can you install the spare and double check the performance?

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I will have a chance to go out to mooring and try that on Weds night. My wife works nights ( not Weds ) and I get to watch over my brood. I find that they are still too young (10,8,6) to just behave and stay preoccupied while I try to work on something.

So I sit and torture myself, WHAT COULD IT BE, waiting till my sweet freedom time, and try to machine gun fix everything I can.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Don't torture yourself too bad. I did that when I spun the prop on the Bayliner. I was clueless about spun props and could only see dollar signs.

My latest and current stress point was last Thursday. I picked up my Explorer back in Sept and have been working on her since. I just finished resealing the stringer outdrive and just put her in the water Thursday for her maiden shakedown cruise.

I followed the manual's instructions about filling both upper and lower units with oil but didn't realize on the upper unit that there were TWO oil plugs on the side of the unit. I didn't recognize the nearly hidden upper plug as being the fill plug I should have filled to, rather I filled to the lower plug. So I'm out testing my outdrive with minimal oil.

Fortunately she needed a tune up so bad that I could not get the RPM's much over 1000k so no damage occurred but I still stressed about it. I'm over it now. She's now filled to the proper level and seems to be none the worse off for it. I tuned her up but have to rebuild the carb and replace the accelerator pump so she'll run properly.

It's always something!

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

My concern over this is just that I don't want to do any further damage by taking pot shots at a fix.

I hope it is the prop. The thing that bugs me about it is I don't remember feeling a resistance when turning the prop by hand, while the forward or reverse mags are powered. I could be wrong.... I thought that it had locked up in one direction and free spun the other, I just don't remember.

I will try to change the prop at my mooring. I am going to take my old shiner net and hang it below the prop in the water.....One time, when I was 13 or so, I was running for home ( In my old 15' Chrysler, yes Chrysler) in front of a storm that eventually overtook and beat the crap out of me. The trough was so deep that inbetween swells could only see water, both sides, rise up see the whole world, drop down again. I must have hit some storm debris, and broke my shear pin, and didn't have another. I couldn't reach the prop from in the boat. I tied a rope around my waist and jumped in. Swam, more like groped, my was to the outboard tip, managed to get the nut/ cone and prop off and dropped them back into the boat. The whole time heaving up and down with the swells, the damn outboard kept hitting me in the head, shoulders and chest. Got back in the boat, was able to cut two bluefish hooks with sidecutters to the right length. Took everything back into the water, got the crap kicked out of me again, bleeding freely from a few locations, that damn skeg hurt, got the two hook shanks into place as a shear pin and got the whole thing back together. I put it in gear and only gave enough to keep the bow into the waves. Rode the storm out, made it to a remote beach, found a piece of drift wood with a 8 penny nail in it. Dug that nail free, cut it to length. Replaced the two hook shanks with the nail, made it back into the bay, made it back to harbor. Made it home for a first rate spankin from dad for staying out all night, and worrying him sick with the storm. That was in the NE in early November, if I recall it right, that water was so cold, it would probly kill me if I tried it now.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

My concern over this is just that I don't want to do any further damage by taking pot shots at a fix.

I hope it is the prop. The thing that bugs me about it is I don't remember feeling a resistance when turning the prop by hand, while the forward or reverse mags are powered. I could be wrong.... I thought that it had locked up in one direction and free spun the other, I just don't remember.

I totally understand. At this point, you only have two sources of the problem. The prop; cheap (in comparison) to validate and repair, or the outdrive itself; painful and much moola!

Reminds me of a time I spent $70.00 to replace an electric fuel pump on a classic car I had only to find out the $1.50 filter was clogged. I now have a spare fuel pump. JEESH!

I will try to change the prop at my mooring. I am going to take my old shiner net and hang it below the prop in the water.....One time, when I was 13 or so, I was running for home ( In my old 15' Chrysler, yes Chrysler) in front of a storm that eventually overtook and beat the crap out of me. The trough was so deep that inbetween swells could only see water, both sides, rise up see the whole world, drop down again. I must have hit some storm debris, and broke my shear pin, and didn't have another. I couldn't reach the prop from in the boat. I tied a rope around my waist and jumped in. Swam, more like groped, my was to the outboard tip, managed to get the nut/ cone and prop off and dropped them back into the boat. The whole time heaving up and down with the swells, the damn outboard kept hitting me in the head, shoulders and chest. Got back in the boat, was able to cut two bluefish hooks with sidecutters to the right length. Took everything back into the water, got the crap kicked out of me again, bleeding freely from a few locations, that damn skeg hurt, got the two hook shanks into place as a shear pin and got the whole thing back together. I put it in gear and only gave enough to keep the bow into the waves. Rode the storm out, made it to a remote beach, found a piece of drift wood with a 8 penny nail in it. Dug that nail free, cut it to length. Replaced the two hook shanks with the nail, made it back into the bay, made it back to harbor. Made it home for a first rate spankin from dad for staying out all night, and worrying him sick with the storm. That was in the NE in early November, if I recall it right, that water was so cold, it would probly kill me if I tried it now.

Sad that you didn't get rewarded for coming back at all. Dad's can be like that more often than not.

Check the prop first. You might have to pay for someone to validate it for sure but it's a cheap investment to find out it's not the outdrive.

 

[Lyndy]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Given the year of the boat you may have the shear pin type of prop. Should be able to see it after you remove the nose cone. I also checked the 1975 235 outdrive and it also had the shear pin.

http://i147.photobucket.com/albums/r282/Lyndy_photo/Misc/propshear.gif

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Hi Lyndy,

Yeah It is that type. I have been advised elsewhere that even these shear pin props still have a pressed hub that can still spin, even if the shear pin remains intact.

I do try to find as much info as possible, espeacially because of my situation of having to wait till the time that I can go and work on it. I do not intend to promote any other forums on a different forum site. But I will say that there is one that caters only to my ancient breed of OMG

Bottom line, I guess that I will find out about the prop for sure on Weds eve.

What I am trying to figure out is: A) Is this true about the props?
B) If I did smoke the e-shift components would I still have both forward and reverse gears albeit < 1000 rpms?

 

[bruceb58]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

May want to double check that you still have the ground wire between the drive and the intermediate housing. It is a stainless steel wire. Another thing is if the connections for both the reverse and forward coils are all good. You can put a current meter inline to see if both forward and reverse are within spec(manual will have this).

Other than those few things, I would suspect the prop hub as well.

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Hey Bruceb58,

I did that this spring, once I got it all together. I have not double checked recently, maybe it's time. I had to do a complete electrical overhaul when I started this restore. I was warned about the importance of protecting and babying this e-shift. I gave it a dedicated wire from the ignition that nothing else "taps" or "draws" off of. When I do marine or even my old pick up wiring, I coat the contact areas with never seize (it is a great conductor), then cover the whole connection with a generous couple of layers of indian head gasket or liquid electrical tape. I know, overboard, but I seldom have any electrical troubles.---It does however, make for a PITA if I have to alter or change anything.

 

[Lyndy]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

If the Shear Pin is still intact and you do not have an intermittent short going down to the lower unit and the ground is intact and well grounded (As Bruce58) mentioned AND when you went over 1000RPM you did not hear a clunk from the lower unit as is it lost power then you would be back to the prop hub slipping.

 

[KRH1326]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

The outdrive turns silently. Not a peep, squeal, whine, thunk, clunk, nada. The only sound is a very faint thud, when it goes from nuetral to forward or reverse, it is so soft that you feel it more than hear it. I believe that it is just the point of engagement.

The prop continues to turn when I broke 1000 rpm, just not any faster, actually I think or felt that it slowed down a little, losing some forward momentum. At that point I had throttled back down to feel it bite or grab water again, just to keep heading back to mooring.

 

[BLDFW]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I tell ya....gotta be a bad hub in the prop. That is EXACTLY the behavior of a spun prop.

 

[Bondo]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

I try to NEVER hijack a thread, but this seems to be a dead thread--

NO PM, but Bond-0 could you take a crack at http://forums.iboats.com/showthread.php?t=335419

Ayuh,... Sorry,.... I just Don't do Stringer drives,... No Clue....

 

[Lyndy]

Re: Elec Shift- Spring/Magnet Issue or Prop Slip?

Wow, didn't think the thread was dead. I believe KRH1326 got his likely culprit answered 3 times. Must not have liked what he read. Wonder how many will help him now. I know of least one that won't. Good luck!