1969-1972 mercury thunderbolt 800 80 hp ouboard troubles!!

[Logansdad]

I bought a late 60's early 70's mercury 800 from an outboard shop this last weekend and put it on the boat. It ran great and shifted fairly smooth forward and reverse. I took the boat to work the next day to drill the holes in the transom to bolt it down and ever since I tilted it up all the way the thing won't shift into reverse now. I can un-hook the shifter cable and if I force it it will engage and go into reverse. Does anyone have any ideas what could cause the shifter rod to bind up like that before I just go ahead and pull the lower end off of this darn thing? Just trying to get my 2 boys out on the lake to do some fishing this year and this thing is being a headache!! Any help would be very much appreciated

 

[Chris1956]

Re: 1969-1972 mercury thunderbolt 800 80 hp ouboard troubles!!

I would suspect the MerControl or the shift cable. Remove the shift cable and work the MerControl to see if the travel is sufficient to make the motor shift into reverse. Maybe the plastic barrel nut slipped or stripped?

 

[cr2k]

Re: 1969-1972 mercury thunderbolt 800 80 hp ouboard troubles!!

Those old control boxes have some very weak points, but parts are available.

 

[Logansdad]

Re: 1969-1972 mercury thunderbolt 800 80 hp ouboard troubles!!

I made sure that the cable moves freely, if I un hook the cable its still really hard to get it to go into gear manually but it goes with some force. Is there something in the linkage between the cable and lower unit that could bind up or be corroded? The darn thing runs great when cold but once you run it in the lake it dies when you put it in neutral. Basically won't idle when at operating temp. I'm stumped and am trying not to put a ton of money into it. This all started when I tilted it up to bolt it down...

 

[Chris1956]

Re: 1969-1972 mercury thunderbolt 800 80 hp ouboard troubles!!

I cannot think of anything that can bind, except the manual lock down linkage. There should be some hooks that grab the tilt pin to lock her down in reverse and neutral. Maybe you damaged the linkage?