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Question on removing the lower unit

A

abl

Contributing Member
"I think I've got an '

"I think I've got an '86 35HP # A998598...if someone could confirm this, that would be great.
It's been in storage for years so I'm trying to drop the lower unit to change the impeller before starting but it only separates about 1/8 inch. Could this be because the motor might be in gear or am I missing something? Any help would be most appreciated."
 
"Andy, first off, yes, your mo

"Andy, first off, yes, your motor is an 86 model.

Did you disconnect the shift shaft? These have a two piece shift shaft which must be disconnected in addition to removing the bolts in the lower unit...."
 
"it doesn't matter if its

"it doesn't matter if its in gear, you should do it in neutral. did you get the nut in front of the trim tab, and the 1 under the trim tab after you removed the trim tab. If you have all the nuts off then it sounds like the drive shaft has rusted to the crankshaft spline"
 
"Graham, you do not need to di

"Graham, you do not need to disconnect shift shaft on this model, hi have 2 of them"
 
"I've got all the bolts ou

"I've got all the bolts out and the unit dropped about an 1/4 inch at the stern but only about 1/8 inch from the forward section. Feels like something is holding it in so I suspected the shift lever shaft or being in gear. I didn't want to force it but sounds like all is disconnected properly. I'll give it another shot tonight.

JB, when you say "trim tab" do you mean the cavitation plate. I got the zinc rudder thing off(can't remember the name of it) and the nut under it, one just forward of that and the two on either side of the forward end of the lower unit. I think that's it....at least according to the book I have....."
 
"Hi JB, I was thinking this mo

"Hi JB, I was thinking this model had that little connector for the shift shaft behind the rubber plug on the housing - but that's why we need you here
"
 
"yep thats all of them, the tr

"yep thats all of them, the trim tab is the zink plate. The shift shaft is in front, only sticks up about an inch out of the lower unit. It sounds like you have the drive shaft frozen to the crankshaft. This could be bad news. You can do a couple of things, tie top of engine to a tree and put weight on lower, or stap top to something and pull bottom with strap. Do not pry on anything. This being said, you can put the front 2 5/8 nuts back on and put a piece of wood or plastic spacer on top of them, unscrew the nuts to force the lower off. Flipping the engine upside down and spraying drive shaft with wd-40 won't hurt either"
 
I'll give the spacer idea

I'll give the spacer idea a try first!
I had this problem with an old Johnson motor so I know how much "damage" I can cause by prying....I ended up having to remove the head to replace the bearing in the head since I destroyed. Thanks for the heads up and the advice.
 
"under the carb is the shift s

"under the carb is the shift shaft linkage, you can gently pull up on that to verify it is not the part frozen on the lower unit. Check the splines on cranck and lower unit if you do get it apart.
Graham, I think of you like the son I never wanted.
talker.gif
"
 
"I think you may be right JB,

"I think you may be right JB, the pulling is in the front end, it might be the shift lever spline that is frozen. Originally, I thought about removing the link on the top of the shift lever, but couldn't see a way of removing it. So, rather than do damage, I thought I'd ask you guys......thank you."
 
"the drive shaft is also forwa

"the drive shaft is also forward of the center line of the lower unit. I don't think its possible to remove the roll pin in the shift shaft arm at least not without removing the powerhead, which you can't do untill the lower comes off."
 
"Help!

It just won't co

"Help!

It just won't come apart. I can only get it apart about 1/8th of an inch. I tried to "shim" it apart using the nuts and it is so tight that the tops of the nuts are deforming. I even put the engine horizontal on a bench, hooked on the end with the transom bracket and attached a come-a-long to the lower unit, with tension on it I hit it with a rubber mallet.....it wouldn't budge. Now it's staning up side down on a 2x12 and I sprayed a ton of PB Blaster against the water pump hoping it will flow to the bearing at the head.....any other suggestions out there would be greatly appreciated. How do they do it in the repair shop?"
 
"let the P.B. work for a day o

"let the P.B. work for a day or two. it's pretty good stuff. hopefully it will help. most shops wouldn't mess with it. take your time, don't go nuts, and good luck."
 
"Thanks, I just hope I got eno

"Thanks, I just hope I got enough in there and it gets to the right place...."
 
"Andy, stand it on its head or

"Andy, stand it on its head or hang from the tail, then spray lube the shaft. It will run down there. Put a tire or mattress under it incase it goes over night. Let gravity work for you, the weight of the powerhead hanging can't hurt anything, just keep it just above ground level. The only other thing to do without tearing anything up is run the engine on a hose if the pump still works with all the bolts removed from the lower. The vibrations might knock the rust out. I would let it hang and walk away."
 
"I've got it hanging now t

"I've got it hanging now thanks JB...and I'm walking away. I used two pieces of 3 foot angle iron. I made a bridge between my bench and a saw horse, the motor is hanging from the "bridge". The edges of the angle iron run along each side of the motor in the small separation I was able to get.....it's gravity's turn.

I picked up this engine around 1990 and it's been in storage since, I never started it and don't know anything about it. It looks to be in pretty good shape from what I can see. A little green on some of the terminals and two wires are worn through from hitting the flywheel (they are g/w and g/y coil wires from the switch box). I was going to fix the wires adn try starting it but was afraid that the impeller would break apart and clog the passages so I figured the impeller should be the first thing to replace. I'm a shade tree mechanic but often wonder if there is some kind of trick that I'm missing. Thanks for your help and I'm sure I'll have more questions soon."
 
"those wires are the coil lead

"those wires are the coil leads, repair them or it will wipe out the switch box if it hasn't already. You don't need the wiring harness to run it, just pull start and cover the battery leads if you want. Drop some oil in the plug holes, pull start to check for spark, remove brass cap at bottom of carb, remove or clean main jet there.
http://www.themarinedoctor.com/cgi-bin//YaBB.pl
bottom right for vidio and service of systems"
 
"help.Need to replace water pu

"help.Need to replace water pump on 2003 Mercury 25hp, I removed the bolts (4) from the lower unit it dropped 1 1/2". Does the vertical shaft and the shift linkage seperate from the Prop' Shaft? The model# OT675533 and I.D.Plate reads 25 ELF. what's ELF stand for."
 
"These are known for getting s

"These are known for getting stuck. The drive shaft was carbon steel back than. You may never get it off. If you do, it the spline is going to be bad in the crankshaft where it connects. Stand the motor upside-down on the floor as spray blaster so it runs down the drive shaft."
 
"As for the 25 hp question. Th

"As for the 25 hp question. The shift shaft disconnects behind the electric starter down inside the bucket. ELH means electric start, long shaft, tiller handle. There may be a S.S. flat washer on top of the shift shaft for the auto reverse lock to work. Don't loose it. It falls on the floor."
 
"Bandit, If I cannot get the

"Bandit, If I cannot get the lower unit to drop after sitting for a week what do I do? Do I just use the motor and pray the impeller never breaks down by keeping an eye on the tell tale stream?"
 
"Bandit Thanks. Do I need to r

"Bandit Thanks. Do I need to remove the starter to disconnect the Shift Shaft Linkage. Also the main Shaft does it disconnect from the top too, If so how by Gravity! Does the water tube disconnect at the lower unit were I got it seperated. I opened the housing for the water pump impeller it's worn out. Thanks, 25HP merc.2003"
 
"Hi Guys, just a quick questio

"Hi Guys, just a quick question:

If I cannot get the lower unit to drop after sitting for a week or two what do I do? Do I just use the motor and pray the impeller never breaks down by keeping an eye on the tell tale stream?"
 
It is time to take it to a dea

It is time to take it to a dealer / repair shop to see if they can help you.Some shops may have the technique to solve your problem in short order.
 
"Andy, there is no other trick

"Andy, there is no other trick to doing this. You can get a new lower unit off e-hey for less than $100. Which brings me to saying you will have to saw yours apart. I'm in the Saint louis/Illinois area, maybe you're close by. If you have to tear it apart just don't ruin the upper half, and maybe you can salvage the powerhead. See ya next year."
 
"Thanks JB, I wish you were cl

"Thanks JB, I wish you were closer but I'm in Rhode Island. I had the motor hanging for a week and decided to try and fix the coil wires and see what I really had. Once I cleaned up all the connectors and replaced the starter selinoid, she turned right over. I had the spark plugs out and the boots were resting against the powerhead.....Huge sparks. I was pretty happy with that. I checked my compression in the top cyl and got a 125. I couldn't get my pressure guage into the lower cyl. so I left it at that. Now for that Darn Lower unit. The thing is, it looks brand new....no dings and only about a 1/2 inch of paint worn off the skeg....It would kill me to have to cut the thing off......we'll let it soak for a few month and then try again. Thanks again and have a great Christmas."
 
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