Lower Unit Removal Question

[FranksMerc]

I'm trying to remove the lower unit of my 1994 115 HP Mercury. I read the manual and have been careful not to miss any bolts. I loosened (5) nuts. (4) on the side and one in front of the trim tab. There's no nut under the trim tab. <br />The unit won't budge. I have it in forward and think that one of the (4) bolts is packed with corrosion and preventing the unit from falling. This one bolt has no free play in it where the others have some movement. My question is there a good way to loosen this? and Is there anything else I may be missing? <br />I tried WD40, gently tabbing with a mallet. Any help is most appreciated

 

[The Marine Doctor]

Re: Lower Unit Removal Question

Sounds like the line up pins are holding it in place. You will need a dead blow to remove it. Sometimes I will carefully pry against the stud and the anticavitation plate "carefully"<br /><br />TMD

 

[FranksMerc]

Re: Lower Unit Removal Question

Thanks for your reply. I have been careful not to cause more trouble than I can fix. I will try some carefully applied force. I tried hitting the trib tab portion with a mallet lightly to see if it would budge. I'll try again. Can you be a little more specific where you pry the unit apart? Thanks again!

 

[tmac58star]

Re: Lower Unit Removal Question

My merc is different that yours, but not that much. First time I tried to drop the lower and service the water pump I had the same problem. I could get it slip/drop a fraction, mostly visible right on the front of the leg, then it would stop. I finally got it free by using wooden wedges on that little front gap, widening it until I could add wedges to the sides, between the hold-down bolts. Once you get it off/down it won't be as hard to do in the future. I can now drop & replace my LU in about 5 minutes...given the right amount of refreshing beverages beforehand.

 

[The Marine Doctor]

Re: Lower Unit Removal Question

Where the studs come down through the gearcase. Push against that and the plate just below it.<br /><br />Not too hard though as you may break the anticavitation plate.<br /><br />They can be stuborn..but they do come off.<br /><br />TMD

 

[FranksMerc]

Re: Lower Unit Removal Question

It still won't budge even a fraction of an inch. I think one of the four bolts is corroded and "locking" the unit so it will not move. <br />Could it be possible that the disimilar metals binded together. The aluminum casting and the stainless steel bolt? If so would heat help? <br />Any further suggestions are appreciated. Getting close to turning this one over to a pro but not giving up just yet.

 

[andrewkafp]

Re: Lower Unit Removal Question

You shouldn't have corrosion problems S/S bolts.As the doc says.. They can be stubborn.<br />Keep at it..<br />There is a long post here, but it ends with the owner getting the L/U off.<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=008376

 

[gss036]

Re: Lower Unit Removal Question

Heat would help. but I think I would leave that to someone with experience, you get the aluminum too hot an it is history.<br />I am not familiar with your engine, but your manual should have told what bolts,etc that had to be removed, double check it. There is a product on the market called "Break Free", I have use dit for years, spray it on a let it soak in.

 

[gss036]

Re: Lower Unit Removal Question

FranksMerc,, did you ever get the lower unit off? Be nice to know since you started the thread. Thanks.

 

[FranksMerc]

Re: Lower Unit Removal Question

Not yet...still stuck. I tried prying, malleting, and its not budging at all. I heard it could be stuck permatex used last time the pump was changed. I really think its one of the 4 side bolts. 3 have play in them and one is just solid. I tried hitting a mallet against a wrench to loosen it but no luck. Unless I'm missing something obvious I don't know what else to do except pay someone who will probably hit it harder than I am. If the drive shaft is stuck how would I loosen that? The lower unit was dropped 3 years ago so don't know if thats a possibility. This board is great and I thank you all for your ideas. Anymore would be appreciated. Landlocked til I fix it.

 

[CU2NITE]

Re: Lower Unit Removal Question

My 150 has a bolt on the back side facing upward and it has to be removed in order to drop the lower unit. Maybe you have this bolt also. I to have the 4 other bolts and the trim tab that needs to be removed along with the bolt underneath the trim tab. Good luck.<br />CU<br /><br />-------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[FranksMerc]

Re: Lower Unit Removal Question

I've looked for the bolt you mentioned and cannot find one. I took the covers off the motor mounts and nothing of that description was there. But the unit is not moving at all so it seems like I'm missing something.

 

[FranksMerc]

Re: Lower Unit Removal Question

Can anyone verify that there are (5) bolts holding this lower unit? The manual says so, but they can be wrong.

 

[FranksMerc]

Re: Lower Unit Removal Question

Anyone ..anyone...(5) bolts total right? Thanks in advance.

 

[The Marine Doctor]

Re: Lower Unit Removal Question

2 On each side..one in the back. Might be under the trim tab.<br /><br />TMD

 

[gss036]

Re: Lower Unit Removal Question

FranksMerc, I had mentioned heat earlier in the post, I say that because when I had my 1st water pump changed after about 8 years( I really pushed it until it went out and peeled rubber in the housing, lucky I didn't ruin my engine) my mechanic had to use a torch to get my lower unit to let go as it had never been removed. I have an after market extention kit on mine for the 30 inch shaft. Maybe you should check with a good mechanic in your area since you have not been able to get it off.

 

[FranksMerc]

Re: Lower Unit Removal Question

One more question...Is there any disconnection I must do to the shift shaft on this Mercury 1994 115 HP. I thought it was a splined shaft that would just slip away but someone mentioned there may be a set screw. Does this seem right?

 

[FranksMerc]

Re: Lower Unit Removal Question

Made some progress....used the pry bar technique and cracked it enough to wedge the lower unit open. Have it clear right to the trim tab bolt and it will not budge. The bolt is just behind the trim tab. It seems "frozen".<br />I am going to get some "break free" as mentioned, but does anyone have any tips. I tried a mallet, pry bar, hammer w/ wooden bolock etc....Thanks in advance!

 

[gss036]

Re: Lower Unit Removal Question

If that is the bolt that holds on the trim tab, some well meaning mechanics like to put a "lot" of Locktite on them. They rhink they are doing you a favor or else they have a trick they use to get them loose, anyone have any ideas???

 

[tmac58star]

Re: Lower Unit Removal Question

Guess you could torch the trim tab off, to get to the bolt underneath. Then after you get the lower unit squared away, replace the bolt under the trim tab, the trim tab and the bolt that secures it. But then again I like to play with fire/torches.