Mariner 115hp lower unit removeal

[Rickyroo]

I just purchased a Mariner 115 as a parts motor for my 1979 mercury 90hp. both have the inline 6 (tower of power) motor. I believe the motor is a 85 or 86 not really sure, however I know some of the parts are interchangeable. I am have a lot of trouble getting the lower unit off. I got all 7 bolts off and 2 of the 7 are loose pending the drop of the unit. I have looked all over to find out why this unit will not drop. after getting everything undone I got it to drop about 1/8". I don't want to pry on it and bend the shiftier or break off something. Any help would be great thanks.

 

[racerone]

Re: Mariner 115hp lower unit removeal

You have the hidden bolt under the trim tab out ?------Put some thick washers above those 2 nuts on the side.-----See if you can apply gentle pressure with those to push the unit off.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

I did do the washer thing, no luck.... I did remove the hidden bolt too and it still will not come lose.

 

[racerone]

Re: Mariner 115hp lower unit removeal

Perhaps the driveshaft spline is rusted into the crankshaft spline.----Salt water motor ?

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

Looks like it was in saltwater at some point but the rust on it is not that bad. Very minor. How can I get to the spline? I have taken off all the nuts to the mid section and it has not separated.

 

[Chris1956]

Re: Mariner 115hp lower unit removeal

Gee, That gearcase should be held on by 5 nuts and a bolt (under the zinc anode). The nuts are all the way in front on top of Anti-ventilation plate, two directly behind that and two more under the anti-ventilation plate.

Make sure the SS washers are off, as sometimes they can bind stuff up. You can whack the studs with a hammer if you pad the studs with a piece of wood.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

I got all of the nuts and bolt taken off. I got all the SS wahers off as well. I am going to try whacking the studs and see if that frees things up. Will post with outcome.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

Still will not come free. I am at a total loss now. Any other ideas?

 

[TD_Maker]

Re: Mariner 115hp lower unit removeal

After you have whacked it a few times with a RUBBER Mallet and that does not do the trick, I do have a suggestion for you. I just loosened a lower unit on a Honda, and previously on my Mercury by doing this trick I l learned right here on this forum.

Lower the unit to the full down (or close) position. Make sure you pad the ground to catch the lower unit as it drops. You don't want it dropping on the skeg. Ground the spark plugs or make sure the safety switch is engaged so the motor does not start. Now, hit or bump the starter several times and the lower unit will possibly fall right out....both mine did, and I live on salt water.

 

[BatDaddy1887]

Re: Mariner 115hp lower unit removeal

TD_Makers idea seems like it should work well. Just in case that does not work either, since you can get 1/8" apart, perhaps you could squirt some PB Blaster in there and let it sit for a few hours, squirt more in, try to turn the shaft, squirt more in and let it sit overnight. Maybe that would free up the shaft.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

The motor does not run however I guess I could hook up a starter and put some power to it and see what happens. I have hit it with a hammer and just can not get the front side to come free. The back (by the prop) looks like it is all free just the front side seems stuck.

 

[TD_Maker]

Re: Mariner 115hp lower unit removeal

The motor does not have to run...just turn over.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

Ok, i have tried everything. I can not get the lower unit to come free. it looks like it is hanging up towards the front of the (the end away from the prop) of the lower unit under the T/T system.

 

[Chris1956]

Re: Mariner 115hp lower unit removeal

Well, the driveshaft is near the front, and the have been known to rust to the crankshaft. Last resort is to hang it by the gearcase, an inch above the ground. Then liberally spray penetrating oil thru the crack between midsection and gearcase. With any luck that oil will drip into spline and loosen it us. Use some good oil like PB Blaster. maybe you will get lucky.

 

[TD_Maker]

Re: Mariner 115hp lower unit removeal

OK. One final suggestion which may work for you. I mean, at this point, I would be trying anything and everything. I had to do this on a 1987 Mercury 70 HP salt water motor a while back. Folow my suggestion I posted above.

Then:
1. Remove Spark Plugs (Makes motor turn over faster)
2. Get a nice chunk of 2x4 and a rubber mallet.
3. Get a partner to turn the motor over while you whack the lower unit downward along the edges of the lower unit at the same time.

The combination of the motor turning over (vibration) and the shock of downward pressure from the (mallet/ wood) blows finally knocked my lower unit loose.

 

[racerone]

Re: Mariner 115hp lower unit removeal

Normally the 2 nuts on the side of the motor do not come off untill there is some gap established.---------Maybe not original ?----------Any pictures of this motor.--------What I have done is used a hydraulic puller to pull off stubborn units.

 

[Chris1956]

Re: Mariner 115hp lower unit removeal

I guess the really, really last resort is to pull the prop, bearing carrier, propshaft and remove the pinon nut. At that point you can destroy the plastic water pump cover and maybe the driveshaft will slip out of the gearcase. I have never had to do that, but it might work.

 

[BatDaddy1887]

Re: Mariner 115hp lower unit removeal

Put all the bolts back on and run it up to temp and try to take it off. Or, heat the shaft with a torch and use an air hammer, you may need to replace some seals after an apocalypse like that.....

 

[racerone]

Re: Mariner 115hp lower unit removeal

Heat the shaft with a torch ???------I think the shaft is hidden inside the exhaust housing and difficult to get at.

 

[Rickyroo]

Re: Mariner 115hp lower unit removeal

I have been having soaking parts in break free however not having much luck. I took off the nut that holds the prop however I cannot even get that to come off. Is there a hidden clip or something holding it on? I am going to try to break free the power head off and see if I can maybe pry a little with a little heat towards the top end. I cannot run the motor it is mostly just the block missing the wires and other pieces needed to start it.