stuck lower unit

[salvageman]

Hi, I have a 2006 EFI elpt 4 stroke 90 HP Mercury outboard motor. I am trying to get the lower unit to come off. I have removed the 5 nuts that are shown in my manual. I can get the back of the two pieces to separate an eighth of an inch but the front is still tight. I was told by one mechanic that the shift shaft needs to be separated first on a four stroke or it won't ever come off......I think that could be for a different four stroke model-like a 50 HP. I have consulted with a friend who is a Yamaha mechanic who says it's probably just the front dowel pin....before I keep reefing on it, does anyone know for sure that I am correct-that the shift shaft is just splined together and should not prevent this separation?
And if this is true, does anyone have any tricks to loosen the dowel pin?

(Please don't respond with "there's another bolt under the anode trim tab" as this model doesn't have it.)

If not, how do I access the shift shaft connection point and where do I separate it?

Please help if you know the answer. Thanks!

 

[wmconway]

Re: stuck lower unit

Mercurys typically use a rotating shift shaft that is splined. Look under your carbs while someone else shifts the motor in and out of gear, to see if the shifter action is up and down(push/pull) or rotary. If it rotates in the horizontal plane - then you have a rotary type that should just pull out. Even if you have a up/down shift action, the act of shifting should cause a lower unit to drop down. My guess is that you and i are in the same boat and we have a stuck drive shaft.

 

[salvageman]

Re: stuck lower unit

I agree.....but I think we are in the same boat because we have stuck dowel pins....hope I'm right for both of our sakes because the other sounds more involved....I'm going to try to get some liquid wrench to seep in towards the front and see if that and a little tapping does any good.

 

[marineralec]

Re: stuck lower unit

I hope you guys are right,re stuck dowel pins.I have just removed the lower unit from my Mariner 60 hp two stroke,admittedly it hasn't been touched for more than 10 yrs-what appeared to be stuck dowel pins,was a frozen drive shaft.It took 2 days in total to get it apart without damaging the ally cases,including suspending a 100 LB weight from the lower unit and hitting this weight with a lump hammer and drift-liberal use of WD40 or similar is good-I would start with spraying and a few smacks with a rubber hammer-I wish you luck.

 

[salvageman]

Re: stuck lower unit

....Isn't it so handy that they make these parts in a way in which they can routinely get stuck? I mean geeze how many people have these same problems, it's all over the postings. Maybe I should go to school to become an outboard engineer....

 

[marineralec]

Re: stuck lower unit

In my case,it was my own fauly for not following the service and lube schedule-but there is no way it will get stuck again!!

 

[pinellas50]

Re: stuck lower unit

The dowel pin on my 96 115 is always the hang up point when trying to drop the lower unit off.

 

[1nebel0]

Re: stuck lower unit

I have a 2004s 115 4 stroke and nothing is holding you lower unit if you have all the bolts out except the front dowl pin and or the drive shaft...here is what I did that took 2 hours of patience...the marine shop I buy parts from gave me the scoop on how to do it if it was going to come down....start with very stiff thin putty knives...you will need two of each...then you step up to larger ones as the gap increases...I bought a big chiesel and went back and forth and finally after a long time and lots of swearing it dropped... it was the dowl pins loaded with salt as the boat came from New Jersey...The lower unit should be taken down every year or at least every two years for an impeller and new grease on the drive shaft splines as well as cleanup the dowl pins. Let us know of your success....

 

[1nebel0]

Re: stuck lower unit

Forgot to give you the ugly side..since you can't get oil up to the drive shaft splines, you would cut a hold in the mid section, saw the drive shaft in half, drop the lower unit and use a puller to pull out the cutoff shaft hanging up in the power head...oh yeah, take a small loan out for a new drive shaft, and having the mid section welded up....you will be ok..just be patient and don't beat on the aluminum as you will break the caviatation plate for sure if you use a hammer....

 

[salvageman]

Re: stuck lower unit

Thanks Everyone. Yesterday I was using a stiff putty knife and spraying the dowel pin area with WD40 hoping that it would migrate through the crack and up while I wiggled the drive back and forth. I will keep at it everyday for a while and see if it comes loose. I'm pretty sure it is the dowel pin now especially after hearing comments above. I have been thinking that some hardwood wedges might also be of use. I will let you all know if it drops. Patience, patience.

 

[marineralec]

Re: stuck lower unit

I tried wood wedges,but the wood kept deforming.I think the putty knife is good,see if you can get 2 in there,more wiggling,then a 3rd and so on-it is all to do with maximum surface area contact to avoid distorting the soft ally-I was packing the gaps with copper coins (we have a nominal 2p piece,that is about 1" diameter)Kept feeding these in,all around as the gap slowly grew.if I had to do it again,I might stand the outboard upside down to try and get wd40 where it is needed-as you say,patience is key.

 

[salvageman]

Re: stuck lower unit

....still working it.....

 

[Mi duckdown]

Re: stuck lower unit

Wd40 is worthless. pb blaster/kroil, my favorite is, marvel mystry oil.

 

[fisherguy123]

Re: stuck lower unit

a mechanic told me he uses kerosene to loosen stubborn parts.....might be worth a try !!!

 

[salvageman]

Re: stuck lower unit

OK....success....not on my part mind you, but after a lot of sweat and soaking dowel pins in mystery oil....which didn't work....I found a good boat mechanic guy at a local shop who got it off and this is what he did....figured I'd share it with the world.....like me he had the idea of getting as much space between the upper and lower sections on the back end of the motor as possible and worked two thick putty knives up each of the sides toward the front....then by closing the gap in the back with upward force, the theory was that with the shims in the middle would force a gap to open up front.....what I tried was to put the aft nut back on and tighten it and to hit the front down with a hammer and block of wood....my theory was correct but my actions were not successful....what he did was to hit the underside of the back of the lower section up with (some sort of) a heavy (rubber?) mallet....when the gap towards the back closes (with a jolt) it wants to open a gap in the front (with a jolt), sort of like a seesaw would move, because the putty knives are in the middle....the putty knives being the axis point.....pretty smart and it worked..... no damage suffered, impeller was full of sand and the cup was scored and corroded.....glad I saw it through...