Lower unit removal (stuck) 1988 Merc 45hp

[fallautumn2]

Hi guys,

I'm new to this forum - and I need help. I was taking my daughter out in the boat for her birthday, when the impeller died - ending the trip very quickly. I am curently trying to remove the lower unit to replace the impeller. I have removed all bolts and the unit has only moved down 1/4", despite my best attempts. It won't shift any further. DO you know what I have done wrong??

Your help will be greatly appreciated. Thanks in adavnce.

 

[arimatation]

Re: Lower unit removal (stuck) 1988 Merc 45hp

I think it needs to be in forward gear? But don't force it....

Others should chime in..............I hear an echo

 

[DuckOfDeath]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Did you remove the trim tab and remove the bolt inside there? If so, you may try a rubber mallet while you hold the LU to prevent it from smacking the ground once it does come loose. You're close.

I have the same model and year motor. I love it.

 

[emckelvy]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Make SURE all the bolts are pulled including that one mentioned under the trim tab.

The upper shift rod might be frozen to the shift shaft, you may need to use heat and/or penetrating oil to break it loose. Use caution if using a torch in this area, be aware that there may be plastic shift interlock pieces in there which are flammable if heated too much.

One tip, don't use screwdrivers to pry the lower unit apart. You'll break the gearcase or mar it badly.

One thing that works real well on a reluctant lower unit is to use wedges. I have some machinists' wedges which are thin, tapering and made of steel. These are great to get in tight gaps and have lots of surface area to spread the force.

You can use hardwood wedges or the plastic ones sold for splitting wood. Tap in a wedge on either side of the gearcase in the rear, then do the same at the front. Keep an eye out for what you're tapping the wedge into, you can do damage to parts & pieces within.

You'll find that the force generated by (4) thin wedges will far exceed anything you can do with big screwdrivers, for example. I've gotten many lower units down by using wedges.

If you get the gearcase down a ways more, but it's still resisting, you can stack wedges to give yourself more prying power.

As a last resort, or in combination with the wedges, a Wonder-Bar construction prying tool is broad and thin enough to work without damaging things.

HTH & let us know how it works out.........ed

 

[fallautumn2]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Hi guys, thanks for your suggestions.
In reply: I already had the motor in fwd, and all bolts including the one inside the trim tab have been removed. I think the idea that emckelvyat had re the wedges is a good one and I'll give that a go (just need to find wedges now!!).
ANOTHER QUESTION: Am i correct in assuming that the shift rod is splined (ie like the crank/drive rod), thus no need to un-hook any linkages under the cowling??? Once again thanks for your help - you are a top bunch of guys.

 

[Really Old Guy]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Rubber mallet! When you get it of, use never seaze, on all
the threads.
I'll remember the wedges also.
I use baling twine the keep the LU from falling (you know like
in a bale of hay). Short hunk of rope works also.
If it's apart 1/4 inch, get a can of break free or tri power,
use the tip ans spray some on those parts.

 

[emckelvy]

Re: Lower unit removal (stuck) 1988 Merc 45hp

ANOTHER QUESTION: Am i correct in assuming that the shift rod is splined (ie like the crank/drive rod), thus no need to un-hook any linkages under the cowling???

Yes, they are splined. The only reason the shift would hang things up is if the shift shaft splines were corroded inside the mating part of the upper shift rod.

BTW when you're removing the L/U it doesn't matter what gear it's in, Fwd gear usually works out since the reverse lockout latch is disengaged.

The main caution there is, make sure whatever gear the lower unit is in, the remote control box is the same. Otherwise you'll lose synchronization between remote and shift linkage and the most common result of this is being stuck in Fwd gear.

And use caution not to move the shift shaft from its current position, if you do you'll have to make sure everything is realigned before you reinstall the L/U.

G'luck.........ed

p.s. don't panic if the shift shaft is so badly stuck to the shift rod that it pulls out of the gearcase. There's a way to fix that problem without tearing the gearcase apart.

 

[arimatation]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Good info. I am good working on cars. New to working on outboards. I will be doing my impeller at some point in the future.

So is it best to just leave the control in neutral? I read somewhere about using permatex on the bolts instead of neversieze? The point was to keep threads filled with the permatex to keep corrosion at bay.

 

[Brent S]

Re: Lower unit removal (stuck) 1988 Merc 45hp

I was in the same boat as you

I gave up and went to a pro. He used the wedge method and just went slowly and over three days of tapping and letting it sit for a while it finally let go over night. I stopped by at 6 am on my way to work and the unit was on the ground.

good luck, Brent

 

[arimatation]

Re: Lower unit removal (stuck) 1988 Merc 45hp

I wonder where corrosion is more likely, on the shift shaft or driveshaft? I can see using a penetrating oil on the shift shaft being possible. Driveshaft would be impossible.

I guess you could take the outboard off and tip it upside down. That would be a pain.

 

[fallautumn2]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Hi guys just an update. I didn't have any machinist wedges, however I had some hardwood wedges - I tiried these unfortunately they were too thick so no luck. I then attempted brute force to no avail! I did notice however that when I tried to remove the lower unit that I could rock it from front to back i.e it seems to me that it may be stuck somewhere near the middle of the unit (exhaust tube or drive shaft perhaps??) I hope that the drive shaft splines are not totally corroded. I also rang a marine dealer and asked hinm for a quote to replace teh impeller, and he told me that if the lower unit can't be removed then I may as well scrap the engine (I had explained that it looks like a brand new engine, powerhead always sprayed with WD40 after use, no visible corrosion etc). Is the dealers statement a sign that he may be a shonky dealer?? I am concerned that if I can't get the unit seperated then bring it in to him that I may gey a huge bill to cover all the unsuccessful attempts then get told I need a new motor. I would appreciate your thoughts.
Again thanks in advance.
Also 1 other question, where could I find machinist wedges???

 

[arimatation]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Good question........

When I do my lower unit I might need some too. I don't get anything doing a google search.

 

[fallautumn2]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Hi guys.
SUCCESS!!!!
I finally got the lower unit off. I never did track down machinest wedges - no one seemed to know anything about them. I eventually bought some thin metal wood splitting wedges, and some cheep slowly tapered wood chisles. Given the shift linkage flange, bolts, water pump housing, exhaust tube etc you don't get a lot of room to hammer them in. However I found that a good place (with a lot of thick alloy in the respective lower and upper unit housings was at the front and back of the lower unit (ie right at the front near the prop and at the back behind the 2 rear bolts) Don't be afraid to hit these wedges hard - if you don't you won't get any result. Thanks again for everyones help.
PS remember to make sure that you apply grease to the drive shaft, all bolts, pins etc so that next tiem you want to remove teh LU it just glides off.

 

[emckelvy]

Re: Lower unit removal (stuck) 1988 Merc 45hp

So what part do you figure was stuck, the driveshaft splines? If so, you're very fortunate to have gotten it apart at all. Usually the crankshaft and driveshaft rust together solidly and resist all efforts to remove.

If there's a lot of corrosion on the driveshaft splines you might want to take a look with a strong lite at the end of the crankshaft to see if the internal splines in the crank are intact.

When you reassemble, be sure to wipe any grease from the top of the shift shaft, and also from the top of the driveshaft. If you don't, the grease can cause a 'hydraulic lock'. In the case of the driveshaft, that's really a bad thing since it can apply undue thrust on the crank and ruin bearings. Plenty of grease on the sides of the splines is OK.

Congrats on getting it apart, you can mark that one off on your Merc Mechanic Qual Card!!!!

Cheers.......ed

 

[fallautumn2]

Re: Lower unit removal (stuck) 1988 Merc 45hp

Hi ed,
It was definately the driveshaft splines. There was no real sign of corosion (I think the rubber driveshat seals kept the salt water at bay), however the original grease had become so hard that it had acted as if it was araldite glue and had formed a tenacious bond.
I did use a strong torch to inspect the crankshaft splines and they were all intact.
Also re your comments on the grease, thanks to another posting on this forum that I read I knew about the hydraulic lock issue and ensured that all grease was limited to the sides of the splines.
One thing I can assure you of is that I will be seperating the lower and upper units each 2 years without failure - I don't really want to go through that scenario again. The thought of being with out use of my boat over the summer holidays was not pleasant.

 

[arimatation]

Re: Lower unit removal (stuck) 1988 Merc 45hp

I hope mine goes as well as yours does................Good job.