Mercruiser Slow Speed in water

[cdog5000]

Hello,

Thank you for checking my post. I have a Mercruiser I/O boat, I took it out on the water on sunday and the waves were decent. We anchored and upon unanchoring we realized we were really close to shore so everyone got back up in the boat and we started to take off. After sucessfully starting it in neutral we went to put it in gear and it stalled. So we pushed the boat away from shore, put the trim up and started it successfully. Everyone got back on the boat and put the trim back down and the boat was running beautiful. About 10 minutes after this we stopped for some reason and killed the engine out in the middle of the lake. Upon trying to start and put it in gear we realized the boat would not go over ~5-10 mph even on full throttle. So we took a nice unrelaxing ride back to shore and got the boat back home, worried. Once back home we put the muffs on it and started her up, she seems to work beautiful outside of the water. We took the prop apart and it seems to be fine.

I just want some advice on what our problem could be. I did find a random rubber piece when taking the prop apart, I just thought it might've been something that got sucked up somehow, but I have heard about a rubber hub that could be the cause of the problems maybe? Any help would be appreciated!

Thank you!

 

[oldjeep]

Re: Mercruiser Slow Speed in water

Have a picture of the random rubber piece?

Did it look like a piece of this:
http://www.ebay.com/itm/Mercruiser-..._Accessories_Gear&hash=item5d30827916&vxp=mtr

 

[ONEGA]

Re: Mercruiser Slow Speed in water

she seems to work beautiful outside of the water

What do you mean saying this? Did you run the motor in gear at higher rpm's on muffs?

 

[cdog5000]

Re: Mercruiser Slow Speed in water

What do you mean saying this? Did you run the motor in gear at higher rpm's on muffs?

The prop would spin at high speeds with the motor in gear at high RPMs on muffs outside the water.

Have a picture of the random rubber piece?

Did it look like a piece of this:
Mercruiser 3 7 3 7L 3 0 3 0L Exhaust Flapper Water Shutter 60930 | eBay

I found it behind the shaft, I am not really sure if its the exhaust flapper or not, cant tell.
Here is a picture:

Thanks for the reply's guys!

 

[Fun Times]

Re: Mercruiser Slow Speed in water

I found it behind the shaft, I am not really sure if its the exhaust flapper or not, cant tell.
Here is a picture: View attachment 206756

Thanks for the reply's guys!

Tough to tell for sure, Do you have a picture of the propeller hub? Maybe it will help?

Since you have the prop off the boat, it would be best for you to try and find a propeller repair shop in your area and have them inspect it if possible.

 

[ONEGA]

Re: Mercruiser Slow Speed in water

The prop would spin at high speeds with the motor in gear at high RPMs on muffs outside the water.

I'd try another prop in water first. You may not see a problem with no load on the prop.

 

[alldodge]

Re: Mercruiser Slow Speed in water

I think you spun the prop hub. With the engine not running and on the trailer put it in forward gear, take a hold of the prop and turn counter clockwise (put some real mussle in it) and if the prop spins on the shaft, you spun the hub, if it turns the drive you spun the engine coupler (I don't think it's the coupler because you didn't mention burnt rubber). If it's neither of these let us know.

 

[cdog5000]

Re: Mercruiser Slow Speed in water

I think you spun the prop hub. With the engine not running and on the trailer put it in forward gear, take a hold of the prop and turn counter clockwise (put some real mussle in it) and if the prop spins on the shaft, you spun the hub, if it turns the drive you spun the engine coupler (I don't think it's the coupler because you didn't mention burnt rubber). If it's neither of these let us know.

I went and tried to turn it while it was in gear counter clockwise. The prop turned actually really easily. I wasn't able to see if it spun the drive or not though.

 

[alldodge]

Re: Mercruiser Slow Speed in water

SOunds like you spun the hub, but to make sure with it in forward geag try rotating it clockwise; it should also be easy and you will hear clicking which is normal

Edit: When you turn the prop, the shaft is not turning right?

 

[HiRaTa]

Re: Mercruiser Slow Speed in water

Would purchasing a new propeller fix this or should a new hub be bought? how do you know if it is a pressed hub compared to a rubber hub?

 

[NHGuy]

Re: Mercruiser Slow Speed in water

Show us a pic of the center of the prop.

 

[alldodge]

Re: Mercruiser Slow Speed in water

Would purchasing a new propeller fix this or should a new hub be bought? how do you know if it is a pressed hub compared to a rubber hub?

HiRaTa, welcome to the forum

You should ask this question in the prop section and start your own thread.

 

[HiRaTa]

Re: Mercruiser Slow Speed in water

I would have but, my boat is actually at my nephew's house "Cdog" and he is actually asking about my boat. So I was trying to find out if buying a new prop would fix this issue. I am grateful Cdog is trying to help with my boat getting fixed. We have learned a lot this year with our starter boat and now that he has introduced me to this forum we might be able to fix a few more things ourselves. We have had so much fun in this boat but it has cost me a tad bit of money in repairs too. Well worth it though, Thanks for any help you guys can give us!

 

[alldodge]

Re: Mercruiser Slow Speed in water

I would have but, my boat is actually at my nephew's house "Cdog" and he is actually asking about my boat. So I was trying to find out if buying a new prop would fix this issue. I am grateful Cdog is trying to help with my boat getting fixed. We have learned a lot this year with our starter boat and now that he has introduced me to this forum we might be able to fix a few more things ourselves. We have had so much fun in this boat but it has cost me a tad bit of money in repairs too. Well worth it though, Thanks for any help you guys can give us!

If your prop hub has been spun then yes this should fix your prop.
Just to clarify and make sure, I was asking if it will turn in gear both ways. If you can do this and the shaft on the outdrive does not turn then it is the hub.

 

[cdog5000]

Re: Mercruiser Slow Speed in water

So, I have tried the following:



1. When engine in forward gear, I tried spinning prop counter clockwise. The threaded part on the (what I think is the shaft) doesn't turn. When turning it clockwise, It spins for a little then clicks.

2. When engine is in reverse gear, I tried spinning prop clockwise. The threaded part on the (what I think is the shaft) doesn't turn. When turning it counter clockwise, It spins for a little then clicks.

So we just need a new prop, right? The rubber part we found is probably that prop hub I am guessing? I am just really hoping its the prop hub.

As Hirata has said, we are very thankful for all the help guys!

 

[alldodge]

Re: Mercruiser Slow Speed in water

Yep, looks like the hub has spun. You can either replace the prop of have the hub replaced by a prop shop.

 

[ONEGA]

Re: Mercruiser Slow Speed in water

I am just really hoping its the prop hub.

It is.
Get a new one and have the old one rebuilt. It's always a good idea to have a spare. And you can replace it in water.