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1967 65 hp mercury 650 no reverse

M

mhazer

New member
Hi i'am having a problem getting reverse.The lower unit was rebuilt with new gears, clutch dog and water pump. My freind did the rebuild and when i put the boat in the water with the shifter in reverse the boat went foward almost putting it in the back of the truck.I have droped the lower unit several times trying to line up the shift shaft.I was told to put the shifter in reverse and the lower unit in reverse, with visegrips i turned the shift shaft and can get foward, neutral and reverse. As soon as i install the lower and shift to neutral and back to reverse i lose reverse but still have neutral and foward.Any help, i'am not sure maybe the shaft came out of the cam. I got the boat with no reverse and beleive the owner before had tryed ajusting the cables at the motor could the problem be there?
 
Re: 1967 mercury 650 no reverse

The lock cam is in but not hooked up. It dosent look like it should make a differance.
 
Re: 1967 mercury 650 no reverse

If it goes into fwd,neutral and rev when you have the lower unit dropped it is unlikely your problem is there.
Try dropping lower unit again,put lwr unit in reverse,disconnect shift cable and put motor into reverse by hand,then adjust cable loading toward reverse a little.This might sound daft but make sure it's the shift cable that you are hooking up and not the throttle cable.I am presuming you are using a merccontrol
 
Re: 1967 mercury 650 no reverse

I hope he didn't put the shift cam in upside down!

Here's the deal: The shift shaft turns counter clockwise to go from F to N to R. If it works the opposite way, the entire LU has to be dssassembled to flop the shift cam. I suspect that's what is needed.

Jeff
 
Re: 1967 mercury 650 no reverse

Well i can turn the shift shaft cclock wise and get foward ,n ,reverse in that order. when the lower unit is installed it still has reverse. Its when i shift to neutral i hear a click and shift back to reverse the cables shift back to the same spot that it was installed in and i have no reverse. The prop turns freely in both directions in reverse at that piont.
 
Re: 1967 mercury 650 no reverse

Is the shift shaft spring laoded someway? When i have the lower unit dropped and shift the shaft buy hand. I need to push down and keep presure on the shaft to ingage the gears. Other wise it just turns with not shifting into gears. When i push down and find reverse i let presure off the shaft and the prop is still locked in reverse.
 
Re: 1967 mercury 650 no reverse

"Is the shift shaft spring laoded someway? When i have the lower unit dropped and shift the shaft buy hand. I need to push down and keep presure on the shaft to ingage the gears. Other wise it just turns with not shifting into gears. When i push down and find reverse i let presure off the shaft and the prop is still locked in reverse."
:(That I'm afraid means something is out of kilter in your lwr unit.You shouldn't need to put downward pressure on the shift shaft to change gear.I think the shift shaft is not engaging the shift cam in the lwr unit,more likely as Jeff says shift cam wrong way up or back to front,whichever,I think the lwr unit needs to come apart.I wonder if the small clip was re installed?Jeff, any better ideas before he has to go down that road?
 
Re: 1967 mercury 650 no reverse

Thanks for the input. I heard you can pull the shaft bushing and see the shift cam and reposition it from there, or should i just pull the gears. It's starting to sound like the problem is there, I'll take a look tomorrow unless there are any better ideas.
 
Re: 1967 mercury 650 no reverse

I have never had to do anything like that,though I have a spare lwr unit that I am considering tearing down for the fun of it.
I have seen a previous post somewhere about taking out the bushing and jigging it about with a bit of wire to get the shaft in.Might even have been Jeff,but it is worth a try and you'll see if the small e clip is there
 
Re: 1967 mercury 650 no reverse

The cam is definitely in assbackwards. If you rip her down, be sure to bend the tab back before trying to unscrew that big propshaft retaining nut. Oh, and the pinion gear has to come off before the driveshaft will come up.

Jeff
 
Re: 1967 mercury 650 no reverse

It seem to be in right i took it apart last night and the groves are to the left so turning the shaft cclock wise the low side of the cam comes first then the middle and the the high side for reverse. looking on ebay it looks like the cam and shaft are one assembly is it not.
 
Re: 1967 mercury 650 no reverse

ebay part was the upper shift shaft disregard.Had the lower unit off again and discovered that when i shift to neutral the prop clicked in both directions thats correct i believe and half way between neutral and reverse is wear the prop spins with no resistance i think i need to get the cables ajusted. i tryed diconnecting the cable at the motor and shifted the shaft by hand and had the same result. Withthe shifter pushed all the way back it does not fully engage.thinking the shaft needs to be set and then the calbles. My buddy played with this stuff so i know he has it way out. Hes not much of a mechanic. I'll try again tomarrow....
 
Re: 1967 mercury 650 no reverse

Back working on the motor. I've tryed the shift shaft in all positions with no luck. installed it in foward ,reverse,and neutral with the cables disconected,and i can't get all three gears. First with the lower unit droped i still can turn the shaft and get all three gears but neutral clicks when turning the prop. thats were it clicks in to reverse if i go just a bit more with out going into reverse the prop spins freely. Can the cam be worn? As i said i installed the lower unit and moved the upper shaft while installing the lower unit trying to get the spins right. Just cant get it to go in and get all three gears. The upper shaft just above the shift arm has a weld on it is that factory? Or can it just be the carrier housing be pushed out making the shaft have to travel more and not letting me get reverse.
 
Re: 1967 mercury 650 no reverse

Ok you are getting all gears while unit is off.Put lower unit in reverse,where the prop locks in both directions.I know you have done this before,humor me:D,push the upper shift lever all the way forward with curved tip of the shifting bar jammed against the block.Slide on the lower unit having a buddy move the upper shaft slightly until it slots over the lower shaft.
When you get the two side nuts on shift the shift lever back one click,you should now be in neutral,prop spins freely.If it does good,then push it forward to reverse again and the prop should lock up both ways.If it does YIPEE.if not :(,there is a problem,says you tell me something new,I'm wondering clutch dog.
The shift bar is generally held on the upper shaft by a pin through the center.
If the unit is in reverse when installed it should only need to travel the same distance to go into reverse again.
I thought earlier about backlash measurements,are they within spec?Backlash is the amount of movement between the drive shaft and prop shaft before the drive turns the prop shaft.
If it turns out to be a worn cam,PM me with your address and I will send the cam in the pic to you free of charge cause I'm running out of ideas
 

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Re: 1967 mercury 650 no reverse

I have tryed it sevel times pushing the shaft all the way back to the block. When i put the lower unit back on i shift to neutral and it clicks and i get neutral and foward but no reverse. it seems that it should go back to reverse but it's like i need just alittle more travel and i cant get it. then if i move the shaft one more splin it jumps over the cam into foward. I'am not sure of the back lash as a freind did the lower unit replacing the gears and clutch dog. and bearings. still not sure about neutal like i said i clicks on the clutch dog in both directions if i turn the shaft cclock wise just a bit more with a vise grip it spin freely but i have to hold pressure on the shaft between the neutral click and reverse to get it spinning freely. Could that be a worn shaft cam. or do i check back lash first.
 
Re: 1967 mercury 650 no reverse

Look: the shifter turns COUNTER clockwise as it goes from F to N to R. If yours shifts the other way, the cam in the LU is in upside down.

Jeff
 
Re: 1967 mercury 650 no reverse

:)I was afraid you were going to ask that. You really need a manual if you need to do anything with this.And is something I would rather take to a very experienced tech.And I ain't no tech,note user name:D
Unit has to be dropped and dismantled....again
Backlash the play between the drive and prop shafts or to be more precise the play between the gears and the pinnion.
Adding or removing shim material affects the gear movement,fwd gear adding shim reduces backlash,pushes the fwd gear tighter to the pinnion,less play,so adding shim increases backlash on rev,which is why I thought it may be slipping in reverse,too much play.
Or it may be that your pinnion is not deep enough,that means you must add shim to it,and when I think about it that may be why you need to push down on the shift shaft to engage gears.You need to open the unit up again and have a look,push down on the drive shaft and see if the teeth are engaging all the way.Is the bearing on the drive shaft fully seated?
But you really need a manual,Selocs walks you through it pretty well.
I'm not passing the buck,I'm just out of ideas and beyond my ability.
 
Re: 1967 mercury 650 no reverse

mhazer said:
Well i can turn the shift shaft cclock wise and get foward ,n ,reverse in that order. when the lower unit is installed it still has reverse. Its when i shift to neutral i hear a click and shift back to reverse the cables shift back to the same spot that it was installed in and i have no reverse. The prop turns freely in both directions in reverse at that piont.
Click to expand...
Hi Jeff,
He says here on 6/13/ that he's getting gears cclock wise,unless he double tapped the c and I misread it and that was why I was exploring the idea that there may be too much shim in the wrong place,or the pinnion not engaging enough,you didn't double tap the c did you by any chance mhazer? Regardless, if the cam is in upside down your still pulling it apart...... again:(
 
Re: 1967 mercury 650 no reverse

Yes the cc was short for counter clockwise, and i don't think the cam is in backwards because it works correct when the lower unit is droped. Still no replies on the cam being in neutral and sounding like the clutch dog is clicking in both directions. look at prior post for details.
 
For anyone looking at this thread. I fixed my problem by pulling the carrier and prop shaft out and reinstalling them. Not sure what the problem was but I think the reverse gear wasn't seated all the way.
 
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