[badazzamc]

I have a 79 mercruiser out drive, and when you put the boat in reverse the out drive lifts up out of the water. As soon as you take it out of reverse it drops back down. Any ideas?

 

[Suta99]

thats just the prop pulling the outdrive backwards. I'm not familiar with the 79 but whatever holds the drive from pivoting up is not there or not working

 

[BATLWGN]

does the outdrive raise and lower just fine out of the water? I am suspecting the hydraulic trim rams are shot.

 

[EASY STEP]

I would say the same, if the outdrive has lifing rams they maybe bad or depending on the model the lock down level is busted or not working.
Is this a new boat for you?

 

[Motorcitydak]

Bust Out Another Thousand. With the boat out of the water, put the outdrive all the way down then grab onto the bottom of the it and try to pull it up. It should not move at all. If it does, your trim cylinders or valves are shot

 

[badazzamc]

Bust Out Another Thousand. With the boat out of the water, put the outdrive all the way down then grab onto the bottom of the it and try to pull it up. It should not move at all. If it does, your trim cylinders or valves are shot

i can lift it pretty easy, There is a valve attatched to the shift linkage that I was told could be the problem, I have not had time to check into it though.