78 115 Powerhead Removal

[Archnawan]

I'm removing the powerhead on my 78 115, well attempting to at least. I took off the heads and found the starboard pistons both have damage so I want to inspect the internals to see if I can rebuild. I have a manual and have taken everything off to get to the powerhead but its very vague about what bolts to actually remove it from the engine. Can anyone give me a clearer idea of what bolts I need to remove to get the powerhead off? Also, do I need to remove all the covers from the lower unit for any reason?

 

[Joe Reeves]

Re: 78 115 Powerhead Removal

Remove the small covers from directly under the hood pan.<br /><br />There are two 1/2" nuts at and under the front of the powerhead and two bolts (1ea on each side).<br /><br />Four long bolts on each side.<br /><br />Two nuts under the rear of the powerhead, under the exhaust baffle plate.<br /><br />And of course the incedentials in the powerhead area.

 

[Archnawan]

Re: 78 115 Powerhead Removal

Joe, thanks for the help. I'm not sure how you have time to deal with all us motor newbies but I for one appreciate it!<br /><br />Further problems with the removal though. After taking out all the bolts you listed, which I might add helped me when the manual did not, I still can't separate the powerhead. When I put the hoist on the lifting hook the power head pulls up about 1/2" then stops. I can see that it is separated from the base all the way around so I know I removed all the bolts. I can only assume the shaft is frozen to the lower unit. <br /><br />Any suggestions?<br /><br />Oh yeah, the incidentals you talked about I assume are shift linkage, fuel pump, etc. which have all been removed.

 

[o/b tech]

Re: 78 115 Powerhead Removal

Did you make sure to disconnect the shift linkage at the front of the powerhead. There will be a small diameter shift rod that goes thruogh the lower engine cover. If it is still attached it will do exactly what you have described.

 

[Joe Reeves]

Re: 78 115 Powerhead Removal

If you're absolutely sure that there is nothing else holding the powerhead, the problem would have to be as you suspect.... the driveshaft splines being frozen within the crankshaft splines.<br /><br />This is caused by someone previously failing to install the "O" Ring at the top of the driveshaft and greasing the splines.<br /><br />However, it's highly unusual for the powerhead to move upwards any distance at all if this were the case, let alone 1/2". I suspose it's possible but I've never run across that movement with a frozen shaft.<br /><br />After double checking for any other retaining connections, if it is the shaft, you have no choice but to do whatever has to be done......<br /><br />Forcing the shaft back and forth, turning the engine upside down and spraying penetrating oil in that spline area, whatever. A time consuming, nerve wracking ordeal!

 

[Archnawan]

Re: 78 115 Powerhead Removal

I unscrewed the bolt that goes through the shift rod but did not remove the actual linkage arm. I can see the shift rod is free of the linkage though. <br /><br />Not real excited about trying to turn over the motor over, no way do I have the facilities for that! Guess I will have to take it to the shop after all.

 

[Basscat 1]

Re: 78 115 Powerhead Removal

I went through the same thing with my powerhead. It was as Joe mentioned, the driveshaft splines were frozen into the crankshaft. It took me about 4 hours to remove. I kept constant pressure on it with a lift, and pryed up. Mine too would only raise about 1/2 inch. <br />Spray inside towards the shaft with penetration oil. <br />It turns out that the lower crank bearing was just about to let go. I guess it had got hot enough to seize up the splines in the end of the crankshaft.

 

[Archnawan]

Re: 78 115 Powerhead Removal

Dang, and I was really hoping it was the shift linkage!<br /><br />Did you do any damage to the lower unit doing the course of the removal? My fear is all the pressure and prying will damage the lower unit gears then I'm looking at a total lose and a new motor.

 

[phatmanmike]

Re: 78 115 Powerhead Removal

did you remove the lower unit first?

 

[Basscat 1]

Re: 78 115 Powerhead Removal

To answer your question, I did do a small amount of damage to the adapter plate that goes between the powerhead and lower unit. Nothing that a little sandpaper and some extra sealant couldnt take care of.