Ok The Mariner and Yamaha are very similar.
In order to explain the problem, let me say what you should have done to change the impeller.
1-take out kill switch
2-select reverse gear
3-remove rubber cover in leg (or find adjustment nut at bottom of swivel bracket)
5-undo adjustment nut counting the turns or flats
6-drop leg change impeller etc, and reverse order 5-1 above.
By letting it hang on the control rod, you might have bent something but lets work around that.
Tools: Flat screwdriver, 2 x 10mm wrenches, long nose pliers, flashlight.
Identify location of adjusting nut, it is either behind a rubber cover lower on the leg, or it is peeping out of the leg just behind the swivel bracket at the lower part. You must find it first.
By pulling on the control rod, you might have pulled it out of the lower unit too far and there could be oil
leakage, or worse, water going in to the gearbox
. It would be wise to re-do the dropping of the leg to check that the rubber seal that the control rod goes through is intact and in place (Expensive if you don't check)
SO to remove the whole shebang again please follow these steps.
1-remove kill cord
2-remove rubber cover or find the adjusting nut
3-select reverse (as best you can)
4-slack locknut on adjusting nut and undo adjusting nut till its free.
5-undo the 4 lower unit bolts
6-ease away the lower unit completely
Using flashlight, check that the mechanism from the shift lever is operating the square shaft, and the plastic cams. Check that the detante spring is able to click into 3 positions r-n-f. Check that the washer and splitpin are in place to prevent the hooked end of the shift rod unhooking from the cam. Return the shift lever to R.
Check the condition of the seal where the shift rod enters the gearbox
, if all OK then
7-coat the water pump rubber grommet where the water delivery
pipe connects with grease, taking care to not block the pipe.
8-look up the leg to identify the location of the water delivery
pipe and that it is not free like a pendulum but retained more or less center.
9-coat the spline at end of driveshaft with grease
10-offer the lower unit up gently, no force is required, feeling for the waterpump to engage the delivery pipe.
11-the spline should now engage, rotate the prop by hand to align splines.
12-close the gap, and place two opposing bolts in and hand tighten
13-place the other two bolts, and only tighten if you can shut the gap by hand pressure only, if so, tighten to spec.
14-Now, the lower unit is in reverse still, and the lever is in reverse.
15-Screw the adjustment nut onto the shift rod, it should be at least 1.5x diameter inserted
16-place shift lever in N try to rotate prop, it should rotate freely without any clicking.
17-select F - try to turn the prop backwards, you should not be able to, but there should be clicking if you turn it forwards
18-select R - try to turn the prop forwards, you should not be able to, but there should be clicking as you turn it backwards.
By feeling at the prop where the "sweet spot" in between the F and R positions is, you adjust the nut until that spot occurs when the shift lever is in the vertical position. So let me put it another way, one hand on the shift lever, the other on the prop, moving the lever and feeling the prop, find the true neutral at the prop, and then see where the lever is. If it does not agree then adjust the nut so that it does.
Normally you would count the turns, or insert it a specified amount, but you have to "feel" this one, as the kinks in the shift rod might have been pulled out of spec by hanging it while you did the impeller.
Question....how did you get the impeller off the top of the driveshaft if you never pulled it right out?
Hope this helps, now I am in SH12 for hogging the computer while my wife wanted to go online...