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Lower Unit Merc 35

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stormdad

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"I have all retaining nuts off

"I have all retaining nuts off the lower unit, but it will only drop 1/8-1/4". I've tried it in forward as well as neutral, wont drop? Sprayed penetrating oil onto everything I can see through crack, tried prying from front and back. Thinking about getting the mallet after it, but don't want to do any damage.
Any thoughts?

-Chris"
 
"here we go again, If the engi

"here we go again, If the engine hasn't been serviced in a few years the drive shaft rusts to the crankshaft. This can be very bad news, the splines will be damaged to the point that its hardly worth trying to fix up.
Lets make sure we have the 2 studs up front loose. Trim tab removed, and the 2 nuts under the trim tab off. If so first try to put a shim between the 2 nuts up front and the cavitation plate, using the nuts to push on the shims and force the lower off.
If you do a search, last year about this time I tried to help someone else with the same engine. It didn't go so well."
 
"JB,

I have the 2 front nut

"JB,

I have the 2 front nuts loosened up, trim tab removed and 2 nuts under tab off.
The unit drops about 1/8" all around will pivot front and back. Almost seems like its hanging up around the water pump housing?
If the shaft was frozen in place would the front of the L/U drop at all?

-Chris"
 
"It's deffinatly the drive

"It's deffinatly the driveshaft then, it goes through the center of the waterpump housing. Do you understand using shims on the 2 forward nuts, screwing the nuts back on, plastic or hard wood on top of the nuts then unscrewing them. The shims will push the 2 apart. If this doesn't work right away, flip the engine over, head down, spray penatrating oil down the drive shaft and let it soak for several days. Look on ebay for a good picture of the lower unit. Search for one of my post on this same problem, I'll try and find it, he had pitures of a rig made to pull the 2 apart."
 
"Man not looking good!!!
Just

"Man not looking good!!!
Just ordered a bunch of parts and a manual...
Tried shims did not budge. Actually started unscrewing the studs from the lower.
If I take the motor off and turn it upside down how do I spray the shaft with PB blast, I cant see it?
The only thing I can see is the water pump housing.

-Chris"
 
"If all else fails and you are

"If all else fails and you are about to give up...How about trying to offset the unbolted lower unit as much as possible to any given side and then running the motor...yes you will fry the water pump but the offset twisting of the driveshaft which will occur as the motor runs, might be just enough to break it loose from the crankshaft. I don't know how much offset you can achieve with this particular Mercury, but on many omc's there is a lot of room to do this. Make sure the engine is in neutral(maybe even remove the prop for safety) and make sure the lower unit is securely held. As I said, this is a last resort when you have tried everything else and there is nothing to lose.
One more far out, last resort solution might be to destroy the lower unit by hacksawing the aluminum along the propellor shaft until the bottom half of the gearcase is removed. You could now remove the gears, propshaft, and the nut and pinion gear. Replace the pinion gear with a lifting ring and attatch a chain and a very heavy weight. Use that device as a sort of reverse battering ram to attempt to yank the shaft. Better yet, obtain a heavy duty slide hammer like the type mechanics use to pull rear axles and attatch that to the lifting ring directly or with a very short piece of chain...this method of course destroys the lower unit and should only be used if you can obtain another lower unit for a reasonable price."
 
"Bob, all good ideas, I though

"Bob, all good ideas, I thought of them myself in my post above that I linked to Chris. Always good to see someone else come up with the same stuff.
If you turn it upside down, shim it open a bit and soak the water pump housing, some of the lube will run down the housing and down the drive shaft. You can hang it from the rafters from the tail, an inch of the ground with a blanket under the head letting gravity work on it. Its gonna take some patience and improvising. The last one got the re-cip saw"
 
The strange thing is that this

The strange thing is that this unit was off about two years ago with no problems. But I am in harsh saltwater conditions (Florida Keys). I will try whatever it takes to get this bugger off.
Gonna take motor off in the morning and string er up!
Can I try running the engine with the lower unit bolts loose but on in hopes of freeing the spline?
 
"Yes, thats what Bob is sugges

"Yes, thats what Bob is suggesting, with putting a side load on the lower unit. Pushing with your foot or pulling with a rope, just tie the steering wheel straight so it doesn't turn. Always lube those splines up top a bit. The other thing that wipes those out is the lower bearing fails, ruins the seal, washes the grease off the splines. When the seal fails the engine has a internal pressure failure and runs on one cyl, then none. Thats what happened to my 35hp, bearing sucked up through bottom piston and bounced around. I need a piston for my parts engine, you might be a donner
wink.gif


edit, you could put a load on the lower with the shims also"
 
Would it possible/practical to

Would it possible/practical to drill a hole in the shaft housing to aid in getting penetrating oil to the shaft splines?

-Chris
 
"Morning, well it would save a

"Morning, well it would save a little oil I guess. You still have to deal with two pieces of metal rusted togeather for the last 2.5 years and now a hole in the mid section. There is also a coller around the bottom of the engine, its not like you can see the splines to lube them. I would just buy an extral can of lube and start spraying. Did you run it with the bolts backed off and under a load."
 
"JB,

I have to put everythi

"JB,

I have to put everything back on the power head before firing her up, waiting on rebuild kits. I will fire her up with L/U loose and see if that works. If not I'll take the motor off and flip her upside down and begin spraying her down with PB Blast.
I will re post my findings.
Thanks
Chris"
 
"JB,

Just to make sure I&#3

"JB,

Just to make sure I'm following directions here...
I'm going to run it with the lower unit bolts loose in an attempt to free shaft. Do I want shims in the gap between lower and mid while running? Reason I'm asking is because when I have the shims in, the flywheel will not turn (by hand) at all.
Some good news, I checked the power head mounts today and all will turn and are not frozen. In fact a few were loose. Could have lead to this whole mess.

-Chris"
 
"Use your best judgement, the

"Use your best judgement, the shims are putting extra force on the main bearing. Only the upper bearing is a tapered roller, the bottom is a ball bearing. You do have the concept right. Anything you can think of to get it off."
 
"David,

Thanks for the sugg

"David,

Thanks for the suggestion...I wish it were that easy. This model motor does not require the shift shaft to be disconnected. It is a two part shaft and should just separate when the leg is dropped."
 
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