73' merc 650 no reverse

[Reponator]

well here goes. I have a 1973 Mercury 650 3 cyl. that I recently bought. I can get it into forward and neutral, but not reverse. It doesn't make any noise and there wasn't any metal in the lube. I have had the lower unit and tried moving splines, no help. I have adjusted the cable, no help. I tried to find reverse by hand with the lower out and on the motor with the cable disconnected and I can't seem to get a reverse anywhere. Am I missing something on the way this motor shifts? Is there something I can do to help diagnose this? Any help is appreciated.

 

[roger3645]

Re: 73' merc 650 no reverse

With the LU removed try turning the driveshaft clockwise and the shiftshaft counter clockwise. Make sure youring turning the driveshaft clockwise while trying to get reverse. If you can't get reverse then it's internal. From other post I've read reverse is the first gear to go bad.

 

[eli_lilly]

Re: 73' merc 650 no reverse

On the lower unit's shift shaft, forward is like 350 degrees of the travel area and neutral and reverse each have only 5 degrees of the travel area. So it's easy to get it in forward and a little tricky to get into neutral or reverse.<br /><br />- Spin shift shaft counterclockwise with your finger until you encounter resistance<br /><br />- Start turning the drive shaft clockwise (easier with a helper) and use pliers to turn the shift shaft a tiny bit counterclockwise into the "difficult to get into" area. The first region will be neutral, the second will be reverse, and then you go back into drive again. There is only a tiny fraction of a turn between forward and neutral, between neutral and reverse, and then everything else is forward again.<br /><br />When the lower unit is off, it is absurdly easy for the unit to spring back into fwd from either neutral or reverse. I reassemble my lower unit in neutral based on the advice of others here.

 

[Reponator]

Re: 73' merc 650 no reverse

ok thanks guys. I can find a spot just like you said. I must just need to work a little harder at getting everything lined up just right. Thing is I find a spot where the prop is just engaged, no clutching action either direction. Is this how reverse is on these? Thanks.

 

[eli_lilly]

Re: 73' merc 650 no reverse

Yes, that's reverse, no freewheel in either direction.

 

[Reponator]

Re: 73' merc 650 no reverse

Ok thanks that clears it up. I'm pretty sure I have found reverse, but I just barely don't have enough adjustment in my cable at the engine side to get full engagement. I tried to move it a spline at the bottom, but then it was way too far forward to engage forward gear. Is there any adjustment inside the throttle assembly? Thanks, you guys have already been a big help.

 

[eli_lilly]

Re: 73' merc 650 no reverse

Pull the lower unit, adjust the cable at the powerhead, and then reassemble the unit (with everything in neutral). That will allow you to "preset" the cable to get enough adjustment when you do reassemble. On my engine, getting adequate adjustment means that my shift cable slider thing on the powerhead is adjusted to be more fore than aft when in the neutral position. It seems that the cable needs to travel much farther from neutral to reverse than it does from neutral to forward.<br /><br />I just went through all this on my new '72 650 so I am more than happy to share what I have learned.

 

[Reponator]

Re: 73' merc 650 no reverse

Well, after trying all the advice I have gotten and still scratching my head I finally discovered my problem. I post this just as helpful info for anybody else that may need it. My problem was traced down to the coupling between the upper shift shaft and lower shaft was worn and had too much play in it. This made it impossible to get both forward and reverse within the travel limitations of the linkage. I have made an iterim repair and if anyone knows where I might find a replacement part for this I would appreciate it. Thanks again.

 

[ricksrster]

Re: 73' merc 650 no reverse

Try bammarine.com

 

[eli_lilly]

Re: 73' merc 650 no reverse

Reponator, one last thing to try, only because I had the same problem where in the end I thought my coupling was worn. What it was in my case was the plastic reverse lock guide that jams up into the midsection from the bottom. I was reassembling the lower unit by putting this on the lower unit shift shaft and then reassembling. What this was doing was causing the upper shift shaft to slide diagonally forward on reassembly instead of connecting to the lower part of the shift shaft. It took me many reassemblies and like two weeks of thinking to figure this out. Finally it hit me and I pulled the lower unit, took the plastic guide and pushed it into the midsection. I used a screwdriver in the hole of the upper shift shaft's coupler and that's when I discovered that the plastic piece went up much farther than I had expected and it holds the coupler in alignment with the lower unit's shift shaft.<br /><br />I have a shift shaft off of a midsection that I am not using that I can send you, but I think you have to pull the powerhead to replace it, although I am not certain on this. Let me know if you need it, it's looking all redneck on my back pool patio currently.<br /><br />E

 

[Reponator]

Re: 73' merc 650 no reverse

Thanks again guys, I appreciate all the helpful commments. Ricksrster thanks for the link. They have the part, but at $31 I don't know if I will be getting it. Eli Lilly, yeah thanks for the suggestions, but I have taken it apart and found that coupler to be the part. So I put epoxy in there to build up the worn splines and now my motor shifts. This is kinda a temporary repair, so if you have that little coupling, it's probably 1"-1 1/2" long right on the other side of that plastic piece your talking about. Yes I would definetly like to have it and would appreciate it greatly. Thanks again, you guys have been a big help.

 

[eli_lilly]

Re: 73' merc 650 no reverse

I don't know how to send a private msg, email me at eli_lilly@downtowndevelopmentplan.com with your mailing address and I'll send the piece out.<br /><br />-E