Lower Unit Stuck...

haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
I mean I'm getting no separation at all. Advice? I've tried to hammer it and started it with bolts slightly attached to catch it. There isn't even room for wedges. It's a 90 HP Mercury saltwater.

Replies

  • screamin seamanscreamin seaman Posts: 1,492 Officer
    How many bolts have you removed?
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  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    How many bolts have you removed?

    All 5. I have a manual and have also followed this which is how the manual explains to do it.

    After more research I suspect the splines are seized. Any idea what this might cost?
  • Mark O.Mark O. Posts: 3,416 Captain
    Does it have to be in neutral while removing? Im just trying to imagine having the flywheel secured in place so the engine cant turn over...and having someone shift linkage from R to F, while you apply pressure to turn the prop the opposite way...would that rock the shaft against the splines? while a third person pulls downward on the foot??? I don't know if that would hurt the motor so maybe a pro can advise before trying that. Just make sure kill switch is removed if any chance of turning over the engine.
  • screamin seamanscreamin seaman Posts: 1,492 Officer
    There may be some corrosion around the locating pins and studs that won't allow the lower unit to be removed. Lots of white crusty build up around the bolts?
    Break out the BFH and hot wrench.
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  • screamin seamanscreamin seaman Posts: 1,492 Officer
    Mercury uses a splined shift shaft, doesn't matter what gear it's in during removal as long as they're the same when reinstalling. Although N may make it easier to align the splines. And turning the engine backwards won't hurt anything but possibly the water pump impeller. .. and in the case that doesn't matter.

    And you didn't state the year, condition of motor or when the lower unit was removed last. In which case the worst possible reason for not coming off is the drive shaft is corroded into the bottom of the crank.
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  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    Mercury uses a splined shift shaft, doesn't matter what gear it's in during removal as long as they're the same when reinstalling. Although N may make it easier to align the splines. And turning the engine backwards won't hurt anything but possibly the water pump impeller. .. and in the case that doesn't matter.

    And you didn't state the year, condition of motor or when the lower unit was removed last. In which case the worst possible reason for not coming off is the drive shaft is corroded into the bottom of the crank.

    2004, motor was clean and did/does run good. Bolts look good but I PB Blasted them anyway. I'm the second owner and use only in saltwater. Original owner claimed low hours which I tend to believe because he didn't live near water. I've had it for a year and a half and this was my first attempt at L/U removal. I know it has been done before because I found an old impellar in the bilge. It also has little screwdriver **** around the L/U from what looks like it had been "wedged/pried" before. Which brings my next question.

    As far as using chisels, wedges, etc. Wouldn't that cause the aluminum on the L/U to bend away from the housing? It looks like the previous owner may have done this before because there are what looks like little screwdriver **** where the L/U and housing meet. I've noticed water coming out of them before while flushing but just thought it was normal seepage.

    I ask mainly because if the splines are seized the motor is basically trash, although usable for now. Is it ok to crease the L/U if I try to pry/wedge it apart, or will that factor into whatever life the engine has left? Not talking 1/2 inch gaps or anything.
  • screamin seamanscreamin seaman Posts: 1,492 Officer
    As long as both mating surfaces are flat it will be fine. Any raised areas should be filed down. There's nothing that needs a perfect seal in that area.

    Just triple check that all bolts at the rear of the gear case are removed. Sometimes there's a bolt under the trim tab. .. They have bitten the ars of many a people.
    Even if the splines were stuck I would think that lower unit would have a little wiggle to it if all the bolts were removed.
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  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    Thanks
  • surfmansurfman WC FLPosts: 5,370 Admiral
    Low hours doesn’t really mean anything if it wasn’t maintained properly, I wish I had some advice for you but I think SS has covered it well. I bought a 2001 and it had low hours on it but, never had the water pump replaced, I took it to the Merc Mechanic and let them do it, he said he had a heck of a time getting the lower unit off, glad I took it to him. Good luck and don’t break anything, Oh yes one other thing, make sure the shift shaft stays in the lower unit, if it comes out it will need to be disassembled to put it back in. Make sure it is uncoupled first.
    Tight Lines, Steve
    My posts are my opinion only.
  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    surfman wrote: »
    Low hours doesn’t really mean anything if it wasn’t maintained properly, I wish I had some advice for you but I think SS has covered it well. I bought a 2001 and it had low hours on it but, never had the water pump replaced, I took it to the Merc Mechanic and let them do it, he said he had a heck of a time getting the lower unit off, glad I took it to him. Good luck and don’t break anything, Oh yes one other thing, make sure the shift shaft stays in the lower unit, if it comes out it will need to be disassembled to put it back in. Make sure it is uncoupled first.

    Why would the shift shaft come out? "Uncoupled?"
  • surfmansurfman WC FLPosts: 5,370 Admiral
    I am not sure on that motor but on my old 500 (50) the shift shaft had a spline too and it could seize and if you weren’t careful the lower half of the shaft could pull out of the lower unit when you dropped it instead of coming apart at the coupling, it happened to me.
    Tight Lines, Steve
    My posts are my opinion only.
  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    Couple stupid questions here but, If I'm going to hang it upside down, how do I do this? Also, is one of those cheap propane torches enough heat the studs or would that be a waste?
  • surfmansurfman WC FLPosts: 5,370 Admiral
    Cheap propane torch is fine, not sure about hanging the motor upside down though? Like SS said, I would think there would be some wiggle even if the spine was stuck. I agree that it is probably the alignment pins.
    Tight Lines, Steve
    My posts are my opinion only.
  • screamin seamanscreamin seaman Posts: 1,492 Officer
    If you need a torch get MAP gas at least. The yellow can.

    Have you given the lower unit a swift stomp/kick to the side of the bullet? That can help break it loose.
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  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    If you need a torch get MAP gas at least. The yellow can.

    Have you given the lower unit a swift stomp/kick to the side of the bullet? That can help break it loose.

    I banged it with a rubber hammer.
  • jawzjawz Posts: 137 Officer
    you've got some good suggestions...but....honestly,if you're smart - you're gonna quit while you're ahead and send it to a qualified shop/individual...


    this should serve as a lesson - part of doing a waterpump on an outboard is to lube everything.bolts,drive shaft,shift shaft...me,i use and recommend corrosion block grease.run a tap down the bolt holes and run a die down the bolts - this cleans the threads....the driveshaft,it requires lube - without it,it will sieze to the crankshaft....

    be careful using "never sieze" - check the contents,some contain copper and aluminum -this will cause a serious galvanic reaction...
  • haydenfox!#$haydenfox!#$ Posts: 2,382 Captain
    jawz wrote: »
    you've got some good suggestions...but....honestly,if you're smart - you're gonna quit while you're ahead and send it to a qualified shop/individual...


    this should serve as a lesson - part of doing a waterpump on an outboard is to lube everything.bolts,drive shaft,shift shaft...me,i use and recommend corrosion block grease.run a tap down the bolt holes and run a die down the bolts - this cleans the threads....the driveshaft,it requires lube - without it,it will sieze to the crankshaft....

    be careful using "never sieze" - check the contents,some contain copper and aluminum -this will cause a serious galvanic reaction...

    My problem with that is that the engine is not worth the repair. I went to a local repair place yesterday to have a mechanic talk me through what I have done and what I may need to do. He says after everything I have done with no separation, it has to be stuck on the studs. Then the big boom, he said if it's stuck on the studs that way, more than likely theres going to be shaft issues. He showed me exactly what he does with a paint scraper and thin chisel to get separation and suggested I take it atleast that far to see if the shaft slides out. I really can't see paying upwards of 400 dollars to find out it would take much more than that to fix it. Motor is running. I'm going to give it one more shot today then I'll just run the **** out of it, literally. Hopefully I can get a few more months to maybe a tear out of this impellar.
  • eli_lillyeli_lilly Posts: 135 Deckhand
    I've read that if the shaft is really stuck tight, loosen the bolts on the lower as much as you can without taking them off, then put the boat on the water, and throw it in gear and drive around some. Allegedly the shaft will vibrate loose fairly quick. You obviously need to have some planning here to get the boat back to the ramp, but it's an idea I've heard several times and it supposedly works well.
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