Can't drop lower unit

xdays

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Feb 16, 2010
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19
I have a 2003 Merc 90 hp 4 stroke and I wasnt to install a new impeller kit. I've read that you do not have to disconnect the shift rod and need only remove 5 nuts to seperate the LU. The nuts came off very easy, but I cannot get the LU to seperate even a little. I do not want to risk breaking something and creating a larger problem, so if anyone has some helpful hints on how to resolve this, it would be greatly appreciated.

Thanks
 

crem1

Petty Officer 1st Class
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Aug 30, 2005
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365
Re: Can't drop lower unit

If you operate in salt water, there might be some corrosion. WD40 spray it then let it sit for awhile before gently hitting the area, that is supposed to separate, with a rubber mallet
 

xdays

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Re: Can't drop lower unit

If you operate in salt water, there might be some corrosion. WD40 spray it then let it sit for awhile before gently hitting the area, that is supposed to separate, with a rubber mallet

Thank you for the reply. There is not even the slightest opening between the lower unit and drive shaft housing, so I'm not sure were I could spray the WD-40. Any ideas??:confused:
 

crem1

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Re: Can't drop lower unit

Believe me stuff like Deep Sea foam and WD40 act by capillary action, just spray it where the two sections meet
 

Chris1956

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Mar 25, 2004
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Re: Can't drop lower unit

Hey X, I am not familar with your motor, however, most of the Merc 2 cycle motors of that size have six bolts. One is hidden under the zinc anode.
 

xdays

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Re: Can't drop lower unit

Hey X, I am not familar with your motor, however, most of the Merc 2 cycle motors of that size have six bolts. One is hidden under the zinc anode.

Thanks for all the responses. This engine only has 5 bolts, the 5th one sits a few inches behind the trim tab. I'll spray some WD-40 around the joint and see what happens. Thanks again:)
 

crem1

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Re: Can't drop lower unit

Don't be impatient, let it sit like that for a day. Another suggestion, use a hair dryer as a heat source and then spray some more of the WD40
 

Texasmark

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14,544
Re: Can't drop lower unit

I have an '02 version of that engine in 2 stroke so I looked in my service manual just to be sure of what I am about to say. Hopefully the 4 stroke is identical in this area.

As Chris said, there are 5 stud/bolts. There are also 2 dowel alignment pins, one near the very front and the other near the very rear of the lower unit but they are between the midsection and lower unit and cannot be seen externally. For that reason don't expect to be able to twist it to get it off. They possibly could be part of your problem even though they are probably SS and would highly resist corrosion; much better than the alum housing and both would have to be corroded to keep you from seeing any light on either end.

The drive shaft is installed with a thin layer of grease at the powerhead and I think the receiver in the crank is bronze. With a SS shaft, one would not expect that to be your problem. Even if it were you should be able to get some light between the two either in the front or rear. Shifter has some room to wiggle so that isn't the problem. The water tube is copper so that isn't the problem.

Apparently, as the guys have said, your alum mid section is corroded and stuck to your alum lower unit so you should be able to follow their directions and get it free without hurting anything.

After soaking, you might get a 2x4 and a hammer and put some smacks on the LU right at the base of the housing. Don't get out on the wings of the anti vent plate and/or splash guard as they can/will break off or bend.

HTH

Mark
 
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xdays

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Re: Can't drop lower unit

Guys, thank you all for taking the time to help.

Mark, great info! Thanks.

I have liberally sprayed it with WD-40, will spray some more later and the try to release the LU tomorrow. Thanks again.:)
 

gss036

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Jan 18, 2003
Messages
2,914
Re: Can't drop lower unit

You might have to use a torch if it is a salt water engine, the heat seems to help but you do need to careful not to do damage. There are many threads on this problem, some worse than others. MOST people miss one of the nuts/bolts.
 

xdays

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Re: Can't drop lower unit

OK Guys, after liberally spraying with WD-40 and letting it sit overnight I still cannot get the LU to budge. After looking at the SELOC manual I am sure that there are only 5 studs that hold the unit in place, and I've taken the nuts off of all. If the drive shaft is what is causing the problem, how the heck could you free it without dis-assembling the engine? As far as applying heat, where would you begin? How could you apply the heat without damaging the paint?:confused:
 

Laddies

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Re: Can't drop lower unit

There are 5 studs with nuts holding the unit in place, there are also 2 alignment dowels 1 in the front and 1 in the back so the unit must come straight down 3/8" before the is any side ways movement. So with care and a hardwood block as close to the vertical surface as possible use a hammer and see if the unit can be driven off the dowels.
 

xdays

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Re: Can't drop lower unit

There are 5 studs with nuts holding the unit in place, there are also 2 alignment dowels 1 in the front and 1 in the back so the unit must come straight down 3/8" before the is any side ways movement. So with care and a hardwood block as close to the vertical surface as possible use a hammer and see if the unit can be driven off the dowels.

The nuts are off the 5 studs and I have used a wooden block with a 3 lb sledge and still can not get the LU to move. I like to get my hands dirty, which is why I'm trying to do this myself, but it looks like a trip to my local marine tech may be in order.:(
 

blue90HP50

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Jun 9, 2009
Messages
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Re: Can't drop lower unit

Xdays: Please read my post to "turtles11756" dated Feb 13th. Also, leave motor in vertical position to use lower unit's weight to help release. Good luck.
Blue
 

Texasmark

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Re: Can't drop lower unit

I still feel that IF it were your drive shaft you would be able to get one end or the other to "crack" loose.

WD 40 is not that good a penetrating oil. I'd use something stronger like "PB Blaster" (Autozone) or KROIL which is an industrial strength penetrating oil...have a www where it can be purchased (I have used it).

The other thing I PERSONALLY would do if in your situation, having thought about what it's apparently not, is to get a 2" bladed putty knife and sharpen it. Then take it and a hammer and go around the seam. Since it is apparently corroded anyway, any paint that you would damage is probably already damaged.

After you finish with the repair and prior to reassembly, I'd clean up the surfaces of the castings down to bare metal. Then a couple of coats of Zinc Chromate primer and a couple of top coats of Phantom black.

Mark
 
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Texasmark

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Re: Can't drop lower unit

I certainly hope that we get proper feedback from this......we all can learn from this project.

Mark
 

xdays

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Re: Can't drop lower unit

I certainly hope that we get proper feedback from this......we all can learn from this project.

Mark

After 3 days of soaking the juncture of the LU, midsection and studs with WD-40 and Blaster, and pounding with a block of wood and sledge, I can not get the lower unit to budge. There is not enough seperation between the mid section and LU to get a wedge in ( all I'm doing is flattening the wedge) and I have also tried getting a putty knife to slide in with no luck. It certainly seems as if there is another bolt, but the SELOC manual describes only 5 studs that hold the unit in place. I have removed the zinc and trim tab to see if there is a hidden bolt and there is none. The engine is very clean, with the only visible corrosion showing at the steering pivot arm (why that isn't stainless is another question:confused:) All nuts came off very easy and there does not appear to be any corrosion in the stud area or the area between the LU and midsection.

So, it looks like I've reached the end of the do it yourself road and need to take it to a tech. I will probably give it one more shot today and if I can't get it to drop I'll take it in to a shop.

Thank you everyone for all of your valuable input.
 

Texasmark

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14,544
Re: Can't drop lower unit

My serv manual shows a very clear view of the top of the lower unit and I assure you that there are only 5 bolts. I even went out to mine and looked and it is just like the manual. Again, mine is a 2 stroke. Maybe, before you give up, call Merc and ask if their 2 and 4 strokes share the same lower unit.

Sorry you are having these problems. Will surely be interested in the solution.

Mark
 

xdays

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Feb 16, 2010
Messages
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Re: Can't drop lower unit

After applying heat to the joint between the LU and midsection and all 5 studs, I am still unable to get even the slightest bit of separation. I had an old corroded 140 Evinrudewhose LU, once I finally removed all bolts and disconnected the shift rod, dropped with relative ease. I can see virtually no corrosion on my Merc and am having this difficulty...go figure:confused:

Anyway, thank you all for your help...it's truly appreciated. I'll post the outcome once it's resolved.
 

Chris1956

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Re: Can't drop lower unit

Mark, The Merc gearcases that you are looking at in the picture has 5 studs or bolts? I would not think Xdays should have that hard of a time removing it. It is pretty new, and corrosion should be minor.

The old Merc gearcases had three studs, the midsection had 2 studs, and there was one bolt from gearcase to midsection, under the zinc Anode. Is there any possibility that this is the issue?
 
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