1974 Mercury 650 shifting problems! Please help.

concept10

Petty Officer 2nd Class
Joined
Jul 24, 2010
Messages
156
I removed my lower unit and took it to be serviced (replaced shift shaft bushing) and I cannot get the shifter alignment back in the correct order.

When shifting the Mercontrol fwd from neutral the lower unit shifts into reverse and vice versa (reverse goes forward).

I had tried many different ways such as re-installing the lower unit while the shifter is in fwd, neu and reverse (at the same time shifting the lower unit respectively)

At this point, when in the water the and I move the shifter reverse to go forward, the engine seems that it doesn't want to lock into forward. I think the reverse locking cam is also problematic.

Where do I start to begin to correct this? At this time i'm confused and frustrated. Any suggestions? I have read many threads here, but can't get it right
 
M

Maxz695

Guest
Re: 1974 Mercury 650 shifting problems! Please help.

remove the unit when testing to see if your in the right gears spin the prop while shifting neutral spins freely when you shift the shaft to the right it should be in fowards. The prop will lock in one direction and rachet in the other direction going click click click. when you shift the shaft to the left passing neutral you should be in reverse the prop will lock in both directions. Now shift back again one more time to the right to get neutral set your throttle control to neutral and re install the lower unit you should be good to go. You at present may have the LU 180 out of sinc. if you did not remove the cam it will be easier for you to identify the position. when the LU is in reverse the high spot of the cam should be at the front point of the LU Center it lifts the reverse lockdown pin. when shifting to neutral the middle of the cam will be facing the front point center of the LU. When in fowards the lowest part of the cam will be at the point center of the LU facing the boat ^
 

concept10

Petty Officer 2nd Class
Joined
Jul 24, 2010
Messages
156
Re: 1974 Mercury 650 shifting problems! Please help.

Thanks Max, this is some good stuff. I think the reason it's backwards is because I thought fwd was when the prop locked in both directions.

Do I have this black piece installed correctly or up side down?

IMG_1455.jpg


I'm about to try your directions now:
IMG_1452.jpg
 
M

Maxz695

Guest
Re: 1974 Mercury 650 shifting problems! Please help.

second picture appears to be correct for neutral position. Be sure to double check prop spins freely in this posistion or the cam will have to be moved. check forward and reverse before putting it back up. also check the shifter is in the same gear as the gear the LU is in. Mostly ---> Never install the unit in reverse. esspecially if the engine is tilted or you WILL DESTROY THE CAM! the first picture has the cavities facing upwards it is upside down and the bottom picture of the cam goes on top. my 40 HP does not have the piece pictured upside down Just wondering if that goes under the cam and turn it over. just to be clear turn the top of the first picture over and place it first then put the cam in second picture the same way it looks in the pic and test for neutral. the spacer in the first picture should stat the same just turned over and put on first then the cam good luck
 
M

Maxz695

Guest
Re: 1974 Mercury 650 shifting problems! Please help.

I believe my post was slightly wrong the rond circle after turniong it ove faces the main driveshaft as it won,t fit in the housing the other way then put the hi low cam on in the same position as photo # 2 checking to see the prop spins freely. if not find neutral and place spacer and cam as described
 

concept10

Petty Officer 2nd Class
Joined
Jul 24, 2010
Messages
156
Re: 1974 Mercury 650 shifting problems! Please help.

Thanks again Max, with the description in your first post, I was able to get it back together correctly. I went to the lake and tested:

IMG_1461.jpg


Thanks!
 
M

Maxz695

Guest
Re: 1974 Mercury 650 shifting problems! Please help.

You made my day have fun bro
 

concept10

Petty Officer 2nd Class
Joined
Jul 24, 2010
Messages
156
Re: 1974 Mercury 650 shifting problems! Please help.

The engine ran fine in foward, but I thought I should test reverse while I had the chance. On muffs, everything looked well. On the lake, it goes into reverse, and the boat moves, but I don't remember the RPMs being as high as they were. I will continue to investigate this. I think somethings not right with the cam, but i'm happy that forward works properly for now and will fix this soon.

I'm now more worried about the engine itself. I keep having to prime the thing. The engine runs fine as long as it's prime. I was running at 30 mph and its great, but I had to reach back and prime it a couple of times when I hear the engine slowing down.
 
M

Maxz695

Guest
Re: 1974 Mercury 650 shifting problems! Please help.

I would suggest a fuel pump rebuild aslo check for cracked loose hoses both in the cowel area and to the tank also the bulb may have a bad check valve. Does you engine raise when in reverse if so the cam is not on correctly. if you can,t tilt the engine in reverse then it,s correct
 
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