Yamaha Lower Unit shaft seized to the engine block. Now What??

[kitemen]

Hello!!

I have a 1996 Yamaha 250 carb. I decided to remove the lower unit and check the impeller, but it would not come off. I discovered the lower unit shaft seized in to the block.

This is what i did so far. I used a few screw drivers to try to open the gap between the lower unit and mid section. I got like 1/4 in, but i discovered that the shaft moved 1/4 in from the lower unit and not the block. Luckily i have a spare lower unit. I also tried to move the power head from the mid section and nothing.

Here are my options. I think?

I can turn the engine upside-down try to spray some chemical to dissolve the rust, than heat it with a torch.

Or cut a hole in the mid section. cut out the shaft. Pull out the power head, then try to remove the shaft with chemicals and heat.

The last think i want to do is damage the power head which works great. Has this happen to anyone before? what is the best chemical to dissolve the rust? will heat damage the power head? any tipsss???

Best Regards,
Jon

 

[kitemen]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

I guess this problem is not as common as I thought

 

[PBJohn]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

Not to sound trivial but are you sure all the bolts were removed that hold it in place. How many bolts did you take out?

 

[kitemen]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

Im sure they are all out. There were 6 around the lower unit, one on the back, under the trim fin. Today Im going to turn the engine upside-down and try to soak it with rusk disolver. any sugestions? fun project

 

[PBJohn]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

Ahhh! you forgot one more in front of the fin. There should be a one inch hole you need a short extention to get to it. Eight total bolts not counting the one that hold the actual zinc fin.

 

[kitemen]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

I also had that one. I bought this stuff call pb blaster to eat the rust away, hopefully it will work. I can feel the tention in the shaft. Its really seized in there. I dont want to use heat because of the oil seal around the crank

 

[James R]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

You may want to try unbolting the powerhead and heaving on that from side to side. That often breaks the corosion at the drive shaft connection. The gasket often holds the powerhead to the tower so be prepared to pry a little.

 

[kitemen]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

i tried taking the power head off and it didnt even move. I been spraying the pb blasted all week... and Nothing. i will be cutting the shaft Friday night!! its my last resort

 

[pine island fred]

Re: Yamaha Lower Unit shaft seized to the engine block. Now What??

Guess its rare but did happen to me with a MARINER. Wound up using a hole saw on the leg and went in and cut the shaft with a SAWZALL. Pulled the power head off and worked on it for better than a week. Never did get the shaft out. You are lucky you have a spare leg. GOOD LUCK. FRED