71 Merc 650 - no reverse

[aredant]

I just got this thing running great after a week of hard work (thanks Corm) and now today I lost reverse. It began with the control lever jamming around neutral. I finally jockeyed it into forward and could get neutral with some pressure but it would not go into reverse. After running for a while I tried reverse again and the engine make a clunk and jumped a bit. Now I can push the lever into rev. but I get a grinding sound like two gears not engaging. Runs fine in forward, and neut. though. I think I have been having trouble with the rev locking mechanism as well, but I'm not sure if it's related. Control box and cables seem ok. The problem seems to be in the lower unit. <br /><br />I hope I haven't shredded the reverse gear.

 

[ZmOz]

Re: 71 Merc 650 - no reverse

You say it was hard to move the control box? I had a problem recently where at first it wouldn't shift into reverse all the way, then the handle was stuck in reverse. I took apar the control box and the cam inside was worn out, and by the looks of it every old control box is going to wear out sooner or later. Got a replacement cam at the dealer for $26 and it works great now.

 

[aredant]

Re: 71 Merc 650 - no reverse

I have rewired and maintained the box and installed a new shift cable and I am certain these are still OK. Reverse worked fine but was a bit chattery until the failure. I can move the shift linkage into forward and reverse but reverse chatters and does not engage. I suspect that I may have worn reverse shift dogs or perhaps there could be an issue with the shift shaft. I drained the lube and it's good - no shavings. If my dogs were ground off I would expect shavings. A new reverse gear is $230 and I'm not sure I can replace it successfully without special tools. <br /><br />Does anyone have any advice? If it's the gear, I may just run without reverse until next year but I don't want to damage anything else by doing this.

 

[mellowyellow]

Re: 71 Merc 650 - no reverse

remove cable and try to shift manually.<br />this will eliminate cable problem.<br />shift dog can be turned around if worn on one side.<br />good luck,<br />M.Y.

 

[aredant]

Re: 71 Merc 650 - no reverse

It WAS a cable adjustment problem after all! I must have had the shift cable a couple of turns shy. Thanks for the great advice - saved me a lot of unnecessary toil.

 

[greasemonkeyozi]

Re: 71 Merc 650 - no reverse

I wish I had seen this post sooner, I could have saved you some heart ache. I had the same problem where the cable adjustment just jumped out of wack for no reason...gotta keep a close eye on that part of your motor.

 

[bigl]

Re: 71 Merc 650 - no reverse

got the same problem on a 79 1/2 90 inline 6 acks like its not going all the way in reverse whats the best way to adjust the cables with every thing in neutral ar not please help thanks in advance