shift problem

I have a mercruiser 165 hp early sterndrive which I have just installed a new water pump in the lower unit, When I reassembled the upper and lower units with everything in the forward gear position I cannot put the drive in neutral or reverse , did I do something wrong can you please help.

probably, did you remove it as a unit or just the lower half?
did you make sure the upper shoe located correctly in the splined shaft?

I didn't have the change lever from the lower unit lined up with the fork on the upper unit. I rectified this and now i can change from forward to neutral but when I put it into reverse it doesn't fully engage any help welcome

You must start over,

put shifter in forward gear

remove lower, drop down so the splined shift shaft is out of the bronze shift arm.

using pliers turn the splined shift shaft clockwise and spin the prop counter clock wise until it locks/stops.

Now you have full forward geard and the spined shift shaft should be as far clockwise as possible.

while gently holding the prop from truning and keeping counter clock wise pressure on the prop reinstall lower to upper while carefully making sure the bronze shift arm lines up at EXACTLY 12:00 (pointing straight forward) over the splined shift shaft.

Once shift arm and shift shaft are lined up correctly the two halfs can be tightend and this should be correct.

If you are 100% sure you have this correct then we can discuss the shift issue.

Of course because of the age of this there may be several issues contributing to the shifting issue of non fully engagement of reverse.

First thing to do is to look at the linkage in the back of the motor.

Find the shift bracket, find the short shift cable (one that goes to outdrive). the short shift cable attaches to a arm on the bracket, the stud it mounts to can be adjusted. It resides in a slot. There is a 7/16" hex nut under the cable end. Loosening this hex and adjusting the stud away from the pivot point will increase reverse engagement. Do this in small incroments as it will also influence forward engagement. If you go to far the same problem you are having now will occur in forward.


If this fails then you may have other issues.

Also look at where the bronze shift arm in the outdrive where it engages the shift linkage in the gimbal housing.

The U shaped piece the bronze shift arm fits into must be TIGHT to the bronze shift arm.
If it is loose (more than 1/32" total slop then it needs to be squeezed tighter with a good set of pliers. This means the drive must be pulled away from the gimbal housing first to have clear access to the shift arm U.

Also if the bronze shift arm (the very top) is worn this can be an issue. Very common due to age and attempting to install the outdrive when not in forward.
Also if the drive has been installed with great force over time due to the drive not bieng in forward or what ever reason the bronze shift arm and be bent causing weak reverse engagement.