Logo
FULL SITE MENU

omc stringer slips at rpms higher than 2400

G

gel1122

New member
Having issues with my electric shift omc it seems to slip at high rpms and I just had the prop replaced it seemed fine at first until I tried bringing up past 2700 rpms then it started to slip and vibrate significantly and now it can really only hpldat about 2200 or 2400 rpms only letting me go 13 mph! Help any suggestions?
 
If it is in gear then wouldn't it have to be the prop hub? There is no "clutch" on these. If it was the drive slipping you'd hear gears grinding and a lot of metal everywhere wouldn't you?
 
gel1122 said:
I just had the prop replaced
Click to expand...
sounds like the prop to me. What prop did you buy? new? used? you had it replaced? replace it yourself. It's a pin on prop- barely even requires tools to change.
There's only one place on planet earth making new props for those drives and that's Propco. Where did your prop replacer get his?
 
The marine mechanic got it from his prop shop its not new paid about 95 dollars for it! So it could possibly be the hud or the spring now this is my second prop in 3 weeks had the first one put in in april and didnt use it much about 5 times from april to sep but I kept my rpms low at about 2700-2800 maybe getting about 17 mph but the last couple of times I wanted to see if I could get a little more out of her but at 3400 rpm but I lost a prop and now im getting slippage this outdrive is paired with a 5.7 L 350 gm
If it was the spring wouldnt it slip constantly bc right now I can probably hold about 2200 -2400 rpms and cruise at 13 mph?
Thanx for all the info so far tbough!
 
I would suggest you do the " no cost " test of marking the prop!-------The spring grips around the clutch hub and it will let go at times and it can be intermittant.---------You are using the proper oil ( type -C ) in the lower unit I hope.-------If you keep running with a slipping spring / hub it will only get worse.
 
Yeah the type c oil is in the unit just out of curiousity the upper on this V8 should have what type of gear ratio? 21:16? Can I use a 21:17? Im thinking about putting together a secondary unit over the winter to have on standy just in case!
 
I thought you verified that is was a good prop if a mechanic installed it.

So now i have to agree the prop could be slipping. As stated run a line thru the prop with something that wont wash off or scratch a line thru it , if the line does not match up after running the boat and it " slips " again look at the line then you can post the question again.
 
Thanx for the info I will have the prop shop put in a new hub mark it and start from there if the problem continues I will assume its internal like a spring or worn gear!

Thanx Again!
 
you have an "expert marina mechanic", but you're here asking for help from us amateurs.... lol
 
Last edited:
So leave him the old prop when you go to get the re-hub prop and try it. Then tell him to re-hub the old prop. Now you will have a spare.

So say it turns out it is not the prop. Could be. Your back to replacing the spring in the drive. At that point do you trust your expert ?
 
I don't think it would be something I would let him work on I have another lower unit that im working on now the reverse isnt working on it I have checked the resistance on the coil and its fine 5.0 ohms on both have to check the spring at this point but maybe I can find another upper for this lower and have a back up just not sure what the ratio should be is it 21:16 or 21:17 for the 5.7L V8 350 or can I use either one?
 
Hey guys just wanted some insight on what else could be causing my slipping problems I had some time to take apart the lower unit and i didnt find a broken forward spring i found some water in the oil some metal shavings really rough edges on the hub like pieces were bitten off the edge and some wear on the sleeve i also noticed that the shavings might have been getting in btw the magnet and hub i also noticed some rubber pieces hanging around the edges of the upper shaft but i haven't taken the upper apart but im assuming thats my water pump but my setup isnt using that inlet ANY IDEAS?
 
With the coil disconnected on the engine very important, put the drive in gear now try to turn the prop if the prop turns and the ball gears turn it's the coupler.

If the prop tuns and the ball gears don"t turn it's the water pump shafts.

Then again it could be the spring.

This drive should always be run fully down.

Listen i don't want to even write this but i will and i will keep helping you not holding anything back, but your drive is beyond even trying to save.

And about your water inlet not being on the drive could you explain that one ?

I have the last of the stringer year drive, love it and i could have changed it out i had everything on a donor boat i bought just for the engine.

I kept my drive, my friends thought i was crazy.

All i did was change the transom shield one time and they are on like the 3rd set of boots. I can change my prop on the water and my drive turns further.

Yes i had shaft a problem and coupler problem but that was over 5 years ago not bad on a 86' boat.
 
Thanx for the advice I'm hoping its not the coupler and if it turns out to be the water pump shaft would I be better off getting another upper? I was able to rebuild a different lower over the winter it had a broken reverse spring so I replaced and checked it with a battery to make sure it would shift properly I also installed a new shift cable in it as far as the water inlet I was talking about the engine has its own cooling system but I was thinking it probably uses the water pump to cool down the drive? If it turns out to be the upper where could I find one for this setup its a 5.7L V8 gm motor I believe the ratio could be 21:17 or 21:16? Could it also be the fly wheel or the shaft that goes into the coupler? Thank you for all the help I just want to try and get this right once and for all!
 
I'm also having this same issue on my 1977 omc stringer / ford 351W.
I had a shift problem, i noticed it started slipping at 2100 to 2300 RPM. I can cruise around the lake all day at 2100 rpm but the second i go past that i have to go to neutral and then back into gear.

So your saying i can tilt up, disconnect my coil (what coil, Ignition, magnet coil?) put my boat in drive (forward) turn the prop by hand and watch the ball gear turn, and if it turns my issue is the coupler? and if it doesn't turn my issue is most likely the water pump shafts or the gear springs???

my thoughts were the gear springs and i have a set of gears in a donor lower unit but who knows how they are ...

whats your thoughts???
anything would help im [:mad:] that close to sinking it or selling it!!! lol



Master mechanic said:
With the coil disconnected on the engine very important, put the drive in gear now try to turn the prop if the prop turns and the ball gears turn it's the coupler.

If the prop tuns and the ball gears don't turn it's the water pump shafts.

Then again it could be the spring.

This drive should always be run fully down.

Listen i don't want to even write this but i will and i will keep helping you not holding anything back, but your drive is beyond even trying to save.

And about your water inlet not being on the drive could you explain that one ?

I have the last of the stringer year drive, love it and i could have changed it out i had everything on a donor boat i bought just for the engine.

I kept my drive, my friends thought i was crazy.

All i did was change the transom shield one time and they are on like the 3rd set of boots. I can change my prop on the water and my drive turns further.

Yes i had shaft a problem and coupler problem but that was over 5 years ago not bad on a 86' boat.
Click to expand...
 
Yes or i wouldn't have posted it.

You should have started a new thread.

First the prop, most likely.

So run a line thru the hub or mark it in some way, take the boat out and then back in see if the prop is still lined up with the lines. If no you know it's the prop.

Then go from there. Post back but start a new thread please !

Welcome aboard !
 
Back
Top