Gear case removal impossible?

[Henri Koeman]

I have a Mercury 115 ELPTO – 1994 outboard 1115412PD S/N 0G039524
I believe that I have the correct Service Manual for it.
The cooling stream has become weak and the temperature of the engine increased to well over 145 F before I shut the engine off. A couple of years ago, I replaced the thermostat. I have not changed the water pump for the last 10 years, so my goal is to replace that part. In order to get to this part, I have to take the gear housing off. According to the service manual (page 6A-17) I have to remove 4 fasteners (2 on each side of the gear case – these actually are also locknuts and fasteners) and another locknut and washer (in the center rear) and the gear housing should come right off. Not so in this case! There is no screw under the trim tab. I do not believe that there is anything else that I have to unscrew.

Reviewing information on the WEB I found that in some cases some force is necessary to get the gear housing off and use shims to get that accomplished, along with the note to be patient. I have tried the following:

1. Tapped on the location of the trim tab with a piece of wood using a sledge hammer (somewhat carefully!).
2. Cut two pieces of slanted wood and placed this between the flange of the prop shaft and the flange of the drive shaft. These pieces are tapered and I used a hammer to create a separating pressure.
3. Used a utility knife blade and tried to wedge it in the crease between the drive and prop shafts and use a hammer (the knife blade broke off).

The bottom line is that I have not even accomplished a crack or any sign of separation that would allow me to wedge the gear housing off.

I am contemplating whether I should construct a special screw assembly that would provide a larger force than what I have applied so far using my wood shims. I could use some advice on what to do.

Questions:
1. Am I correct that I have made all the disconnections, removed all the necessary screws to take the gear case housing off?
2. Are there any special tools to take the gear housing off? I have not found any mention of that in the service manual.
3. Are there any other tricks to be able to do this?

Any other suggestions?

Thanks!

[Beachcomer]

Maybe not what you are looking for but there are numerous videos on youtube that can help

Pt.1 Mercury 50HP Outboard Water Pump Replacement - YouTube

[Henri Koeman]

Gearcase removal mission not yet accomplished!

Thank you for pointing out the link to a U-TUBE video. I looked at this video carefully, and I am jealous how easy that gear housing came apart, which is shown at the end of this part 1 of a two part series. I searched on the WEB myself before I submitted my questions. I found two other videos on the same subject. Again, no problem taking things apart. In addition, I found also a discussion of a case where it was difficult to separate the pieces. There it was suggested that I use a shim to leverage separation. I cut two pieces of wood and attempted that suggestion. A picture is attached. Again no movement.

So my questions remain:
1) Is there something else that I need to losen up? My maintenance manual does not make any mention of that.
2) While I may not have tried hard enough to pound on my shims, is this a good suggestion, and I should not hesitate to pound harder? I also contemplated construction of devices to push again using bolts, buts and spacer. I am worried about that jumping out.
3) I have (not too hard) used a splitting maul on the location of the trim tab (with a piece of wood for protection). Should I pound harder?

My case may be an unusually extreme case. Internal corrosion may have joint pieces internally. That I was thinking that pounding with a mallet would gradually losen things up. Maybe I have to do much more of that.

A boats.net parts spe******t suggested that I post this information for guidance. I hope that there is somebody out there who has this kind of experience.

Thanks!

Henri.

[boats.net]

You did disconnect the shift shaft.

[Henri Koeman]

Shift shaft disconnect needed?

I have noted that in certain U-tube videos there was mention of disconnecting the shift shaft. However in the service manual for my particular model engine, there was no mention of disconnecting the shift shaft. Therefore I did not make an attempt to find whether there was a disconnect for a shift shaft, and to disconnect it. There was mention to put the gear in the forward position. I suspect that has to do with reconnecting it in the same position as the gear housing is taken off.

As far as I remember, I did not note access to a shift shaft when I took the cowling off. Where should I find this disconnect and have access to it?

Even if the shift shaft is connected, should I not be able to get a small crack between the shaft and propeller housing?

Thank you for your suggestion; definitively something to investigate further.

Henri.

[Ski]

Sounds like the dowel pins are hanging up and or corrosion on the studs, this drive uses a rotating shift shaft similar to the drive shaft. If you have removed the five nuts holding it on I would use a heat gun or torch and heat the front and rear of the flange, if you can get it in there a little lube always helps (studs and flange near dowels), and give the bullet a good beating with a rubber mallet. "Snap-On" has a real good one that's filled with lead shot. Use this web site to see where the dowel pins are and side to side hits might be just as effective as trying to drive it down. Good luck and let us know how things turn out.

[Henri Koeman]

Something to try to get gearcase apart. Is this safe?

I am not much of a boat engine expert, but I try to use common sense, and I have been successful in the past repairing my engine. But this issue has been the most challenging.

1) The five nuts have been removed for sure. A couple of them fell apart on me (no damage to the studs). The studs appeared to be corroded, and I sprayed WD-40 on them and it is soaking as we speak. I do not know at this time where the dowels are located (back and front?) but I will look into the drawings to see whether they are shown. I do have a heat gun for electronic circuitry, but that likely does not have enough heating capacity. I also have a propane torch for copper plumbing soldering. Should I point the torch towards the drive shaft housing or the gear shift housing? Considering a positive temperature coefficient for metals, I am inclined to choose the gear case portion. But I am worried about damaging the bearings and insides. By the way, I have drained the gear oil. I am not really confident in using the torch, but I understand that it is a way to cause loosening corroded internal parts.

2) So far I have used a splitting maul and a piece of wood so soften the blows. Again, I have been relatively moderate. I appreciate the comment on hitting from side-to-side. I will look into getting this Snap-on mallet.

3) I understand from your comment on the “rotating shift shaft” that it is not necessary to disconnect something related to the shift shaft in order to take the gear housing apart. If I am not correct, please comment again.

Again, I appreciate the suggestions. I hope that at some time I can do something back! Once I have this accomplished, I will let you know.

Henri.

[Ski]

The flange area around the studs is where to heat, the attempt is to get the housing to expand enough to release it's death grip on the studs. The heat will also cause the WD-40 to leach up. The Dowels are in the front and aft of the flange also, heating this area will also help. Use your propane torch, But be forewarned that WD-40 is flammable so wipe off the excess and let the rest burn off. Don't be afraid to heat & lube several times, just don't set yourself or garage on fire. Best of luck

[Henri Koeman]

Will be going the heat and tapping route.

Thank you Ski for the more detailed instructions on how to go about this.

1) I will do this work outside away from any building in case of a fire.
2) I will wipe off the WD-40, have the gas hoses disconnected and away.
3) I plan to have a buddy to do some of the tapping while heating up.

In case somebody has alternate suggestions: very much appreciated!

Henri.

[Henri Koeman]

Progress, but need more!

I did use a blow torch to accomplish a creak between the drive shaft housing and lower gear case unit. It seems that the studs and dowel pins have loosened and let go. But something is still holding back preventing anything more than a crack of more than one or two tenths of an inch. I attach three pictures that show how far me and my helper got.
I am guessing that the drive shaft itself and/or the gear shift is holding the two units together. Is there any other screw that I have to take out or make something else loose?
In order to get a shim in front of the separation, I broke the 90º Connector PN 43335. This is a plastic part. A question later to be addressed is how to get the piece inside the draft shaft housing out. Maybe just blow torch it?
Ski or anybody else giving me additional hints? I do not want to force things too much and cause more damage than necessary.
Thanks again,
Henri.

[Ski]

It's going. Use lots of lube from the top and bottom and heat. Now that things are moving you can get in there with opposing screw drivers (larger the better) and pry it down. Use A little caution to avoid doing to much marring of the cases. What your fighting is the aluminum corrosion against the studs. It acts like cement. Driving the lower unit up and down should help get the lube in there. "Heat & Lube" Have fun and let us know when you get it apart.

[Henri Koeman]

Getting the gear housing off is NOT easy!

Ski,
Noted your observation. This experience is certainly a new one for me. I expected that once things started to move, it would be more-or-less a “downhill” matter. Cement crumbles up, I would think. No so fast though Henri. I was getting worried that some other nut had to be loosened. But I do not see anything in the drawings that suggests that. The gear shift shaft rotates when you shift between forward – neutral – backwards. The drive shaft is slotted as well.

You are saying “going up and down” and “heat & lube”. Given that there is at least some movement, does heating still help? It seems that the housing around the rear studs and dowel is pretty loose, but I have more of a challenge at the front. In the back I can get a crowbar in the crack. To avoid marring, I think of using two hacksaw blades and driving a screwdriver in-between them. That should be pretty safe.

Let me know if you have any more comments. Thank you for the encouragement.

Henri.

[Henri Koeman]

Success! (gear case and drive shaft housing apart!)

Success!!!!!

After my last note on the subject matter, after I managed a crack between the gear case housing and drive shaft housing I continued to experience serious difficulty to take the gear case housing off. Then Ski (on this Mercury parts forum of boats.net) advised me to continue efforts using shims, heat, and lube. At that time I was concerned that something else had to be loosened (which was not the case). He encouraged me to continue. In order to reduce marring by wedges, screwdrivers, etc. I used two hacksaw blades and pounded on screwdrivers inserted in between the saw blades to increase the gap. Every now and then I tried to move the gear case up and down. I noted that at the location of a single center stud on one side, something did not move. At all other locations, you could see that the gear case housing was moving relative to studs and the dowel at the front and the dowel at the back. So it became pretty obvious that the “holding” stud was the location to emphasize efforts. Ski pointed out that the corrosion between studs and gear case housing was like “cement”.

Putting my efforts at the location and pounding from the side a screwdriver between my hacksaw blades may have been helpful. I used a torch again, but the effect of that at this stage remains unclear. I put a nut on the stud that I was concentrating on, and pounded on it back and forth (not very hard though) with the purpose to pulverize the “cement”. I tried to open up the gap at the opposing side stud location (that was already loose), with the idea to go “up and down”. My final attempt that finally became successful was to put my hacksaw blades along the long side (back to front of the gear case housing) of the side of the holding stud and pounded a larger size screwdriver between the saw blades, and ….. there the gear case housing suddenly released. I noted that there was indeed significant corrosion at the location where the thread of the studs started. The studs appear to be stainless steel, and the corrosion from the aluminum housing seemed to be filling the space between the threads of the studs and thereby preventing easy demounting.

For those who read this, the original reason for trying to take the gear case housing off was to get access to the water pump (taking that water pump off was a “slam dunk” kind of effort). I searched on the WEB for suggestions, and I found several YouTube videos on the subject matter. It seemed rather straightforward and taking the gear case housing off seemed almost effortless. There are at least two different schemes for shift gear connections. In one scheme you go straight up and down to shift gears, and in another scheme a rotation causes a gear shift. In the first case, you have to disconnect the connection to the gear shift. In the other case, you do not have do anything special to disconnect (my case). The service documentation for my engine suggested to put the gear shift handle in the forward position. Service documentation also pointed out where nuts had to be taken off, which I had done beforehand. Note by the way that in some outboard engine designs there are hidden screws under the trim tab (this was not the case in my situation).

There was one reference on the WEB that did discuss the possible difficulty of taking things apart and suggested the use of shims between the flanges of gear case and drive shaft housings. I did cut a couple of wood shims, but they did not result in any kind of crack when I applied pressure. Ski pointed out that my problem was likely related to corrosion between studs and dowels and the aluminum housing. So his suggestion was to use a torch on the flange near the studs and dowels and pound on the side of the gear case housing with a rubber mallet. The heat causes local expansion of metals and thereby unlocking the corrosion. For the mallet, I only had a metal one, but used a wood block between my hammer and the gear case housing. The location of studs is evident; one dowel is located at the front and another dowel is located at the rear. So I pounded on the left side and the right side. I also tried my wood shims between flanges of the gear shift and draft shaft housing again, and I managed to accomplish a 0.1” to 0.2” gap. But it seemed to be impossible to accomplish a complete separation.

I obtained further advice, and Ski again suggested continuation of the effort, using larger size screwdrivers, heating and lube. To reduce marring, I used two hacksaw blades and pounded a screwdriver between those blades to increase the gap. At some time I noted that I could wiggle the gear case housing up and down and that the pivot point was a single stud. I concentrated my efforts on that location and after numerous tries, I was finally successful. And it was shown that Ski was correct in his assessment of the situation: corrosion near the threads of the studs was very evident. Maybe when I put things together again, I will put a lot of grease at that location to reduce the potential of corrosion.

If somebody who reads this is faced with the same problem as mine, be prepared to spend considerable time. It took me a several hours (with wood shims) to accomplish absolutely nothing; it took myself and my son a few hours to achieve a 0.1” to 0.2” crack; and then it took me another couple of hours to accomplish my goal.

If somebody on this forum wants to comment on this information, in particular if something is NOT a good idea, please correct me; after all I am not an outboard engine expert (I am an electrical engineer, having absolutely nothing to do with outboards).

I hope that this information is useful to others. And again, I thank Ski for sharing his expertise and made me successful in this effort.
Henri.

[Beachcomer]

Happy to hear that you got that thing apart. I was intrigued reading your frustrations with " impossible". I thought, that is always "me".

In the Aviation world I have successfully used a product called "Mouse Milk " to free up frozen stuff. lately I have discovered BP Blaster that also works OK.

Going together, use an "anti-sieze" compound vs grease. Molumendum dissulfide ? comes to mind.

Cheers...from Arkansas !

[Ski]

Beachcomer, are you a A&P?