Force, lound bang full out now shuttering/ vibrating, lower unit?

[Desert Lake]

1996 Force 50 Hp was out on the lake about 10 minutes into my run down the lake there was a loud bang and then my speed reduced. The rpm at idle goes up after 30 seconds idling but engine starts perfect. You can put it into gear and it will go forward but shutters/ vibrates horribly to the point that you don't want to run it. Almost feels like the proper is off balance. No visible damage to the pro I was in 200' of water at the time. Not sure what to even check. I raised the motor and the prop will move in neutral but makes a clicking noise. In gear you can move it but takes some effort with the high compression Force motor.
For some back ground My motor is a 1996 force 50 hp on a 2007 Weeres 21' pontoon boat. I had a cracked block and just put a new power head in from a 1990 Force 50hp. It's running great and had excellent compression. Starts right up but now can't use with this issue. Any suggestions would be awesome!!
Cheers, Mike

 

[racerone]

Check gear oil.

 

[Desert Lake]

Check gear oil.

Check gear oil for metal shavings or do you think being low on gear oil could cause that?
Cheers,

 

[ThomW]

Check gear oil for metal shavings or do you think being low on gear oil could cause that?
Cheers,

Make sure there is any gear oil in it. Could have been way low on lube or water in the lube causing the gears to go boom.

 

[foodfisher]

Bang could have been submerged object. Shutter could be spun prop. Magic marker a straight line accross the hub. Run it and see if the line stays intact.

 

[Desert Lake]

Make sure there is any gear oil in it. Could have been way low on lube or water in the lube causing the gears to go boom.

Do you think adding oil would fix it if it's low?

 

[racerone]

Loud noises usually mean trouble.-----Was gear oil low , yes or no ?-----If oil was low with shiny metal flakes or chunks of metal you have issues.

 

[Desert Lake]

Loud noises usually mean trouble.-----Was gear oil low , yes or no ?-----If oil was low with shiny metal flakes or chunks of metal you have issues.

Going to have to pull the boat out and check it sounds like. It's a pontoon and I rent a trailer twice a year, going to have to rent the trailer or pull the motor to test.

 

[racerone]

Hands on is the only way to check these things.----While boat is out of the water a compression test might be good to do as well.----Loud noises are not good.---Trouble shooting needs to be done.

 

[Desert Lake]

Hands on is the only way to check these things.----While boat is out of the water a compression test might be good to do as well.----Loud noises are not good.---Trouble shooting needs to be done.

Absolutely thanks for the help! Going to pull the motor off so I can check in my garage. The loud noise sounded like it came from the lower unit not the power head. Engine fires right up still but high rpm.
Thanks again everyone for the feed back!!