81 Merc 115 gear case

[~Nickolas~]

Hello,
I just got my first Mercury engine in all these years of boating and it's a 1980 115. For the life of me I can not get the gear case back on. I have dropped many a gear case and replaced water pumps, seals , etc and always got them back on fairly easy but this Mercury is driving me crazy. Am I missing something or am I just holding my mouth crooked? This think does not want to go back on no matter how much I shake and wiggle it. What a pain...

Nick

 

[Chris1956]

Re: 81 Merc 115 gear case

Nick, Set the motor control to neutral. Make sure the gearcase is in neutral as well. Tilt the motor alll the way up and lock it. Grease the driveshaft and shiftshaft splines and shove the driveshaft into the midsection. Turn the flywheel with your hand until you feel the splines on the driveshaft mate. Now you need to mate the shift shaft splines. Put a nut on the studs whenever there is enough sticking out, but do not use anything but your fingers to tighten it. You may need to manipulate the upper shift shaft with a needlenose plier to mate it to the lower shift shaft. Once it mates, wiggle the gearcasse into positon, using your fingers to take up slack on the mounting nuts.

 

[~Nickolas~]

Re: 81 Merc 115 gear case

Whew man what a pain my my rear. This was the most pain in the butt gear case I have ever removed and reattached. I never had any like this one. Usually they just wiggle and fall into place but not this one. Mercury is a whole different animal than what I am used to with Evinrude and Johnson. I do like the way they use studs on the gearcase. Much better than bolts any day. The speedometer in the gearcase is different. I have to familiarize myself with Mercury now after years of OMC.

This inline 6 is pretty impressive. Odd though with it's design. Looks like the block and head are an integral design? Weirdest outboard I have messed with yet. No thermostat I see anywhere. Carburetors look a lot different than what I am used to also. First ones I have seen with external jets. Ignition looks normal though with 2 brain boxes and 6 coils, stator and trigger. Haven't got the boat out tin the water yet but she sure idles well and throttle is very responsive. Anyway thanks for the reply I got her back on. Going to be a fun engine to tinker with.


Nick

 

[Chris1956]

Re: 81 Merc 115 gear case

Yes, that motor does not have a removeable head. It also does not have a thermostat. Make sure the carbs are clean, the ign timing is set properly and the waterpump impeller is good, before trying it out. Those motors are throughbreds, and the mid-range and top-end power is the best. Prop it to run 5200-5500 at WOT.