Lower unit won't come off!

[wingtime]

I'm trying to pull the lower unit off my 1991 Merc 200.  I'm pretty certain I have all the bolts/nuts out including the one hiding under the zinc/trim.  It won't budge!  The most it will come down is barely enough for me to work a putty knife between the LU and mid section.  It's almost like it is still bolted in place.  I've whacked it with a dead blow hammer and jumped up and down on it.  NOTHING!  I was thinking the drive shaft might be stuck in place but I would think I'd get at least some movement out of it if that was the case.   Anyone have this happen to them?

Thanks!

[fitz73222]

Quite common on lower units that havent been off in years. Driveshaft splines are stuck in the crank. Instead of destroying the gearcase trying to get it off; Get an engine hoist, unbolt the powerhead bolts, screw in a factory lift ring and keep the pressure on the powerhead until she pops off the driveshaft. It make take a day or two for this to occur. Dont over do it trying to lift off the powerhead. Just keep adding a little pressure at a time an let it rest. It will come off!!

[slvrlng]

Just to make sure you got all the bolts. Hope this will help too! It does sound like the splines stuck.

http://www.youtube.com/watch?v=E-uzQi7IgwU

[wingtime]

Well the whole point of this project is to change the mid section and lower unit out to convert this motor from a short shaft to a long shaft. (long story about my inability to use a tape measure).  I did decide to go ahead and pull the power head.  I have a lift ring in it and tried lifting it with my engine hoist.  Nothing, it's stuck too. even with the hoist lifting the power head and me jumping on the lower unit nothing will budge.   So I sprayed everything down with PB blaster last night and left the hoist attached to the power head with tension on it.  Maybe I'll get lucky and find it loose when I go back to my shop!  I wish!   I guess I can try driving wooden or plastic wedges between the lower unit... if I can get one started in there.

[fitz73222]

Patience is definatley recommended on this project. Easy on the hoisting or you can damage the main bearing retainers in the block. I had a flywheel that took 4 days to pop. Everyday, 1/2 turn on the puller bolt. My son I were standing next to the motor when she popped and it about scared the daylights out of us! Just constant, increasing pressure each hour or day and it will come loose. Lesson here for everyone. This is the other reason to pull the gearcase every other year or so; to grease the driveshaft splines and look for gas/oil running down the driveshaft that tells you you have a bad lower crankshaft seal that is the kiss of death on two strokes if left unattended.

[seabob4]

I've had outdrives that were just as stubborn.  Trouble is with them, you can't put a hoist on them.  I have a large assortment of starboard wedges I made up from scrap starboard at work, they're a lot better tan wood as they don't splinter.

And it's always rust on the shaft splines that bind them up... :x

[flounderpounder225]

As stated many times go easy, I was pulling an old evinrude years ago, wouldn't come, lifting powerhead, pressuring lower unit.... Bam!! it came off, broke the skirt of the crankshaft where the driveshaft goes in... done...

[wingtime]

Yeah I'm being very mindful of breaking something. Been there done that enough!  That's why I put my tools down last night and walked away from it.  I don't have much pressure on the hoist right now...   Just enough to leave some pressure on it in hopes of it working loose on it's own while I seek advice from those who have gone this way before.   I have some starboard that I was planning in using as wedges.  I don't think who had this apart before put any anti seize or grease on the studs and that may be part of my problem.

[flounderpounder225]

You probably already know this, but it is worth a mention, "when" you are putting it all back together, go easy on greasing the splines of the driveshaft, the grease will create an airtight seal in the crankshaft and I have seen it where you can't get the foot all the way up, it acts like a shock absorber up there.  Just a little will do, plus dropping annually makes it much easier.
Marc

[wingtime]

Well I managed to get the darn thing off.  I just had to take my time hammering in wedges, pry bars, starboard etc in there and slowly worked it down and off...  It was slow going at first and then it suddenly started to move and finally fell two inches to the floor.  In all it took over two hours....  and to my delight... the crane keeping pressure popped the power head loose when the lower unit came off.  I guess the PO never greased the drive shaft since the entire thing has surface rust on it all the way up to the splines.   Now I noticed two things.  One it looks like there is a O-ring inside a stainless collar on the bottom of the crank.  Do you replace that whole collar? or just the O-ring inside?   Also the top of the drive shaft just a cone type top while the new one has a tapered top with a small 1/8" or so pilot.  will that be a problem?  I don't think it is broken off the old once since there is actually a small recess on the tip of the old shaft.

[GoneFission]

Got a manual?  You are at a point where torque numbers and assembly instructions might be good to know.  

http://shop.ebay.com/?_from=R40&_trksid ... Categories

My $0.02

[wingtime]

I have a Seloc manual but it sucks since it if for all outboard models from 90 & up.  Those look like they would be much better.

[fitz73222]

Hey Wingtime,
Congrats on the separation! Now for the pin and O ring. That pin should be spring loaded and it is there to preload the thrust bearing in the gearcase below the water pump assembly. Since the power head is off take a look up in the crankshaft and see if there is a corresponding pilot hole or countersink in the crank recess. Some designs used this preload pin arrangement and others did not. Are you bolting up to a similar year midsection and gearcase assembly? As for the O ring and collar; You should be able to replace just the O ring but sometimes that whole assembly was meant to be on top of the drive shaft and maybe sticking on the crank. Go on to I shop marine website and go to the Mercury store; after you select the horsepower click on the correct serial number for what you have and look through powerhhead, driveshaft and gearhousing views and take a look at the parts views and see what should be there and where. You may have to hunt through different schematics until you find the parts arrangement. Compare it to the parts line up for your old midsection and gearcase and see if anything is different. You should not have a problem with this swap but it pays to check. You`re going from a 20" to 25" midsection right?

[wingtime]

Fitz,  My motor is a 91 model and the new 25" mid section is a 2000 (so I'm told).  The lower unit that was on my motor was a CLE low water pick up type and I'm not sure if it is original to my motor or not.  I have no idea what year the new lower unit is.  We just traded parts for a serviced and ready to go 25" Mercury lower.  I planned on looking up into the crank recess to check for a pilot hole or worse a stuck in pilot shaft!  I'm not sure if the collar comes off the crank since I don't see a shoulder or something that would keep it from sliding down the drive shaft but I will research it more.  Here are some pics of what I have:

Original 20" CLE lower unit:


New 25" standard lower unit:


new 25" mid section:


power head on hoist:


bottom of power head:


Crank collar:

[fitz73222]

That CLE gearcase probably wasn`t the original gearcase unless your engine is an original Pro Max version. Nice gearcase and worth some nice coin! The Allison and Bullet bass boat crowd would gobble that case up. Very heavy duty and made to run cleaver or surfacing props without destroying the bearing carrier. assuming the 25" mid section and gearcase were from a 200, 2.5 liter, 153 inch block; everything should bolt up. Good pictures of the crank; that "collar" is actually part of the end cap assembly to retain the bottom crankshaft seal. You are looking at a seal lip, I believe. You really should consider replacing that seal while the powerhead is on the bench. Its not that big of a deal. Unbolt the cap screws. tap on cap to break the sealing bond and very carefully walk the cap off of the crank with two small screw drivers. You do not have to loosen any block bolts to get the seal cap off. Try not too deform or scratch the mating surfaces and stay away from the crankshaft machined surface that the seal rides on. For the $15 bucks for the seal and Oring it can save your powerhead if it starts to leak and cause one or both of the bottom two cylinders to go lean and fry a piston or cause a bearing failure. See if you have to buy a seal installation tool to set the seal at the right height; it may not be necessary, I just dont remember. You can buy the whole end cap with a new seal installed but rather pricey.