Problem with 70's Merc 200 20HP motor - Very little thrust

[ShastaCA]

Hello all,

I came across these forums today and am hoping you might be able to help me do a little troubleshooting.

I bought a 77 Silvercraft with a Merc 200 20HP motor (I'm guessing the age of the motor is about the same, but I am not certain) about a week ago, and today I took it out for only the 2nd time since getting it.

We were at nearly full throttle when all of a sudden we lost about 99% of our thrust and the motor revved up very high. I brought it back down to minimum throttle immediately, and eventually decided to just use our trolling motor to get us back to the dock, since we weren't far.

I don't know a whole lot about boat motors, but have done a little research since I've been home, and it seems likely that the problem is that rubber hub in my prop is slipping.

I spoke with the previous owner of the boat, who asked me if I could spin the propeller by hand with it in gear. I am able to spin the propeller in one direction when it is in forward and I can hear a clicking sound as it spins. It is locked in the opposite direction. In reverse, I cannot spin it in either direction.

The previous owner thought that it should not be able to be spun by hand in either direction, when in forward or reverse, but a little internet research indicates this may actually be normal behavior.

So, with it being Saturday the outboard shops are closed and I'm wondering if there are others here with knowledge of this motor who can confirm or deny my suspicions of the hub being the problem, as well as the propeller spinning behavior when it's in forward. Also, with the propeller locked in gear, I can get the hub to slip a bit if I turn the propeller with a little force... I wasn't sure if this was bad practice or not, so I didn't want to try too hard. Should there be any give at all when doing this test, or should it feel completely solid (for lack of a better term)?

Any other things I could check while I'm stuck on land this early into what looks like a nice weekend would be greatly appreciated as well.

Thanks guys.

 

[racerone]

Re: Problem with 70's Merc 200 20HP motor - Very little thrust

The clicking in forward is normal !!-----------Try another prop as the hub appears to have lost its friction drive.

 

[oldman570]

Re: Problem with 70's Merc 200 20HP motor - Very little thrust

From what you have stated , it dose sound like the prop hub is spinning. On that motor you should hear a clicking sound when the motor is in foreword when you turn the prop one way, and you should not be able to turn the prop at all the opposite direction, nor when the motor is in reverse. It is a good practice to carry a spare prop when boating, as it can be changed and save the day, not to mention the long paddle back to the dock at times. JMO
Oldman570

 

[ShastaCA]

Re: Problem with 70's Merc 200 20HP motor - Very little thrust

Thank you both for the quick replies, and definitely good advice picking up an extra prop to have on hand... luckily we weren't too far from the dock today, but it would have been terrible to be in this situation several miles out.

Hopefully this is all that's wrong with it. I'll take my current prop to get looked at on Monday as well... If I can just pick up a new hub kit for it, and get a backup prop, that would be ideal (save me a few bucks).

 

[ShastaCA]

Re: Problem with 70's Merc 200 20HP motor - Very little thrust

I just thought I'd post a quick follow up in case someone else down the line has a similar problem and my experience could help them.

I went into our local propeller shop on Monday and picked up a new propeller and thrust washer for my motor. I also left my original prop with them to attempt to press a new hub into it. Unfortunately, they called me yesterday and informed me that the propeller "exploded" under the pressure of the press when they attempted to install the new hub into it. They actually warned me that this was a possibility when I left it with them, so at least I was prepared mentally for this outcome.

We got out on the lake today with the new propeller and everything is back to normal.

Thanks again.

 

[Mi duckdown]

Re: Problem with 70's Merc 200 20HP motor - Very little thrust

Nice to get follow ups with Problems. Sorry about old prop, it happens sometime But rare.