Loss of Power 1975 70hp Evinrude

[mav6759]

I was out fishing and I went to start the motor. The motor was running good all day. The motor was running and the prop hit a log or something before I got the motor in gear and the motor shut down. I restarted the motor but now I can't get up enough power to get the boat off plane. The motor ran and it ran good and took me back to the dock but the boat stayed on plane. The prop doesn't look that bad, it does have a few nicks, but I don't think the prop is the problem. Would anyone know what the problem could be. The motor still starts on the first turn of the key.

Mav

 

[Bifflefan]

Re: Loss of Power 1975 70hp Evinrude

I can't get up enough power to get the boat off plane. The motor ran and it ran good and took me back to the dock but the boat stayed on plane.

"On Plane" is when its running fast and up on top of the water. Not on plane is like when your going slow.
I think you have them backwards.

Check the spark, you may have lost a power pack, adn only running on 2 cylinders.

 

[mrcj001]

Re: Loss of Power 1975 70hp Evinrude

It may have a spun prop.

 

[mav6759]

Re: Loss of Power 1975 70hp Evinrude

Thanks for clearing that up for me. What the motor is doing is not give enough power to put the boat on plane. When I give the motor full power, the motor has enough power to raise the front of the boat to the point I can't see where I'm going. So I had to reduce power to get back to the dock. How do you know if the power pack is blown, or the prop spun,

thanks Mav

 

[aaasnapper]

Re: Loss of Power 1975 70hp Evinrude

Firstly, you need to check for spark on piston. If you found you have dropped spark you need to check all the connections.
After that you will need a DVA adapter and multimeter to check your coils and power pack.

If your prop is slipping you revs would have been increasing with no power gained.

 

[mav6759]

Re: Loss of Power 1975 70hp Evinrude

I think I spun the prop. I went out and checked the prop. I put the controls in forward and tried to turn the prop by hand. The first time I tried to turn the prop it spint a full circle without catching. When it did catch, the prop had a lot play in it. I can almost turn the prop a good 6 inch of a turn before it catches. Is that normal, should the prop spin that far before catching.

thanks Mav

 

[aaasnapper]

Re: Loss of Power 1975 70hp Evinrude

no it is definitly not normal for the prop to do that.
You have obviously damaged something in the lower gear case.

 

[Sixmark]

Re: Loss of Power 1975 70hp Evinrude

Firstly, you need to check for spark on piston. If you found you have dropped spark you need to check all the connections.
After that you will need a DVA adapter and multimeter to check your coils and power pack.

If your prop is slipping you revs would have been increasing with no power gained.

Please try to be accurate, as a DVA adapter is not required to test for spark on a cylinder, it can be checked with a simple spark tester available at your local auto parts store, set it to a 7/16 to 1/2" gap. Running out and buying a multimeter and a DVA adapter is not always an economical option for everyone.

If you were able to get back to shore without any issue other than having a "power loss" I would suspect a spun prop. Being that you didn't mention any symptoms such as a grinding, or periodic clunk coming from the lower unit, I would definately focus more on the prop.

Did you have a noticeable change in RPM after the strike?

Remove the drain plug in the lower unit and check for metal shavings, and or water in the gear lube in any case. This will help tell you if any seals or gears, clutch dog were damaged.

 

[mav6759]

Re: Loss of Power 1975 70hp Evinrude

I did the spark test everything was good, matter of fact I started the motor last night it ran very well no issues. I just put new spark plugs in and only ran those plugs once on the water so far. After the prop hit, you heard a quick grind. But there was no grinding, periodic clunking, nothing from the motor going back to the dock. I did notice a change in RPM's, I just can't tell you how much. Does a spun prop mean that the prop is bad or the shaft the prop spins on.

Thanks Mav

 

[mav6759]

Re: Loss of Power 1975 70hp Evinrude

I just went out to check the prop this morning. As I remove the cutter pin I noitce that the prop nut was lose. I can spin the prop nut with just one finger. My question is, how tight should a prop nut be. This may be the issue to my problem. Or should the prop nut be finger tight and replace the cutter pin.

Thanks Mav