Rebuilding Gear Case of 48SPL

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Oldslowandugly
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Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sun Jan 02, 2022 9:01 pm

I have two 48SPL motors and both leaked water into the gearcases. The saltwater case is frozen solid and I can't get it apart. The freshwater case I am taking apart slowly and carefully. At everythingoutboards.com there are compilations of special tools and parts for servicing older OMC outboard engines, and from them I identified all the special tools I needed to rebuild the gearcases. I found most [of the tools needed to rebuild the gear case could be purchased] at very good prices [by bidding on them at auction websites].
Last edited by Oldslowandugly on Tue Jan 04, 2022 4:39 pm, edited 1 time in total.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Mon Jan 03, 2022 9:52 am

I am having a very hard time extracting the propeller shaft bearing/seal housing from the saltwater gearcase. The recommended puller suffered a broken bolt from the strain. I now have a chain wrapped around the internal cross bars and an automotive grade gear puller clamped to the chain. I have exerted tremendous force, while heating the gearcase with a torch and oiling the inside. It will not budge. Any ideas?
Last edited by Oldslowandugly on Tue Jan 04, 2022 4:36 pm, edited 1 time in total.

Jefecinco
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Re: Rebuilding Gear Case of 48SPL

Postby Jefecinco » Mon Jan 03, 2022 10:38 am

I assume you have tried all the spray products recommended for loosening stuck fasteners. PB Blaster has been more useful in my experience than several others. Having said that I was ultimately unsuccessful in removing the steering wheel from it's shaft on our Sport 13.

When attempting to remove the track sprocket from a bulldozer we were unsuccessful. We had the Cat designed hydraulic puller and had put the maximum pressure on the puller. We heated the sprocket center as much as we dared and the sprocket remained on the drive axle. In frustration someone gave the shaft a big whack with a sledge hammer and the sprocket finally popped off.

Try using a brass drift pin or other soft alternative to pound on the gear case close to the bearing/seal. That and some PB Blaster and heat may help.
Butch

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Mon Jan 03, 2022 11:51 am

Yeah Butch I tried that too. I whacked the sides with a machinist hammer as hard as I dared. Nothing. I am at the point of carefully cutting the case open so as not to damage the parts inside. I have another spare empty gearcase housing but on that one the pinion and forward bearings are rusted stuck. I just ordered the special tools to remove those. That outboard site was super helpful in identifying the tool part numbers. If I can first get those rusted bearings out of the spare gearcase then I am free to cut open this stuck one.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Mon Jan 03, 2022 11:18 pm

My upper bearing carrier extraction tool came today. It is an OMC # 387206 and it clamps around the driveshaft to press it up and out, taking the bearing carrier with it. But the FSM shows a set screw that secures to the water pump impeller flat on the driveshaft. This tool does not have that set screw even though it is the exact tool part number. Maybe it is a superseded model that clamps the shaft tight enough to get it out. I think I will take my drill press and drill a hole and tap it for the set screw. That way even if it slips it can't get past the impeller flat and will raise them up.

Image
Fig. 1. OMC #387206 Driveshaft removal tool
Last edited by Oldslowandugly on Tue Jan 04, 2022 7:08 pm, edited 3 times in total.

Don SSDD
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Re: Rebuilding Gear Case of 48SPL

Postby Don SSDD » Tue Jan 04, 2022 6:05 am

I haven’t done this on a lower unit and don’t exactly understand the details but I have pulled lots of things like steering wheels and other items with a similar mechanical setup. When they stick like this, I have the puller tightened as much as I think it can stand for pressure and they hammer on the end of the shaft, not on the bearing. I use a big hammer and a block of wood so as not to damage threads. If that doesn’t work I put the nut back on the shaft as far as it will go while still protecting the threads and give the nut/end of the shaft a very solid whack with a big hammer. It has always worked. I’ve soaked with pb blaster first and used heat sometimes, propane only.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Tue Jan 04, 2022 11:09 am

Don that has always worked for me on stuff that is solid and secure, like a steering wheel, flywheel, or wheel hub. It is always a shock when the flywheel leaps off the crankshaft after whacking it with a BFH. But the gearcase is aluminum and fragile. The forward gear bearing is about a foot deep in a four inch round blind hole. You can't get a torch in there and the bearing race is sitting on a ledge that you can't get behind. The factory tool gets behind it somehow and pulls it out. If I can get one I will figure out how this works.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Tue Jan 04, 2022 4:31 pm

Today I used the driveshaft removal tool on the freshwater gearcase. I drilled and tapped the tool for a 3/8" set screw like the FSM says should be there. It clamps around the driveshaft.

I pulled the driveshaft, the upper bearing, and the seal carrier up and out while disengaging the pinion nut from the driveshaft.

The pinion nut is a press fit and this tool easily popped it right off.

Once the driveshaft is out the forward gear and bearing and shims can be removed. I tie-wrapped both the forward and reverse gears to their respective bearings and shims so they don't get mixed up.

Then I removed the leaky seals that started this whole project. I used a common automotive seal pry tool to carefully get all the seals out.

Now the gearcase and all the parts are soaking in #2 oil, an excellent non-flammable solvent.

IMG_0253.JPG
Fig. 2. Driveshaft removal tool
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IMG_0254.JPG
Fig. 3. Bearing and seal carrier removed.
IMG_0254.JPG (188.27 KiB) Viewed 1760 times
Last edited by Oldslowandugly on Tue Jan 04, 2022 7:07 pm, edited 2 times in total.

jimh
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Re: Rebuilding Gear Case of 48SPL

Postby jimh » Wed Jan 05, 2022 8:36 am

I noticed in Figure 2 that you added the set screw that was not on the original tool as seen in Figure 1. I would have thought that the circumferential pressure of two halves of the tool pressing onto the drive shaft would have been sufficient to keep it in place when applying upward pressure.

Did the set screw leave a mark on the drive shaft?

Did the two steel bars that are shown in Figure 2 placed under the tool come with the tool as purchased? They look like a good method to prevent the upward-lifting screws on the tool from damaging the workpiece.

ASIDE: nice photography in Figures 2 and 3.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Wed Jan 05, 2022 1:35 pm

I drilled and tapped the tool for the set screw because the tool described in the [factory service manual] had one. I did that because on my saltwater gearcase that bearing carrier would not come out and needed to be chiseled apart. I was expecting the worst but it turned out this freshwater gearcase was not corroded at all. The carrier extracted easily as it should.

The set screw did not damage the shaft. That spot [where the set screw bears against is] where the pump impeller wedge sits.

387206.jpg
Fig. 4. OMC factory 387206 driveshaft extractor tool with set screw
387206.jpg (103.86 KiB) Viewed 1700 times


The factory tool required a plate that sat on the gearcase to protect it as mentioned. None of the factory tools I found included that plate. The plate is a separate part number and I could not find one.

325867_.jpg
Fig. 5. OMC 325867 extractor tool backing plate to protect gearcase
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The aftermarket tool made by Precision Tools did include it. I had a similar plate but it would have needed the hole enlarged. I also had the two stainless bars handy to protect the gearcase and they worked just fine.

jimh
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Re: Rebuilding Gear Case of 48SPL

Postby jimh » Wed Jan 05, 2022 9:26 pm

Thanks for explaining the set screw. I infer that you mean the shaft is rotated so the set screw will bear against the flat part of the shaft where the key for the water pump impeller is located.

dtmackey
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Re: Rebuilding Gear Case of 48SPL

Postby dtmackey » Wed Jan 05, 2022 10:41 pm

Did the lower unit need a rebuild or just new seals? I chuckle at the shop manuals and the tools needed to replace the most common failure - prop shaft seals. A simple trick to the expensive tools and removing the bearing carrier is to screw 2 - 3 drywall screws into the seal on the outer edge away from the shaft and then pry them with a set of end cutter pliers and the seals pop right out. To install the new seals a piece of PVC plumbing pipe sized to the seal is perfect to seating the new seals. I've done countless seals with this method and never bothered with the tools. I can do prop shaft seals in 5 mins or less with this method.

D-

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Thu Jan 06, 2022 8:11 pm

That sounds like a good plan if the shafts are smooth. I have two gearcases. One is saltwater welded together and one is normal freshwater use rebuild-able. Both needed all new seals. On the saltwater case the seals and their casings were corroded away to nothing. Worse, there are deep grooves worn into the shafts where the seals ride. That normally would require new shafts because the seals won't seal at the grooves. I have a fix where I clean and fill the shaft grooves with Marine Tex and then wet-sand that down flush with the shaft surface. If you do it right the shaft is as smooth as a new one and the seal won't leak. But it requires that the shaft be out of the gearcase so I am trying to extract them now. The freshwater gearcase is coming apart easily. It also has some grooves in the shafts but not as bad as the saltwater parts. I learned the hard way that putting new seals on grooved shafts is a recipe for disaster. No matter how small, the grooves cut the seal lips and they fail early.

jimh
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Re: Rebuilding Gear Case of 48SPL

Postby jimh » Fri Jan 07, 2022 12:20 pm

A complete rebuild of an OMC gearcase (30-HP model) is demonstrated very nicely in the three-part presentation linked below. The mechanic does a very good job of explaining each step. He also comments about ways to work around the need for factory special tooling to perform the work. After watching the demonstration, I am impressed with the crafty design that goes into an outboard engine gear case that allows all the work to be done through the propeller hub opening.

The mechanic-presenter in these demonstrations is from an Australian shop, DANGAR MARINE. He seems to know his way around old OMC outboard engine gear cases.

The three parts in order at found at:

https://www.youtube.com/watch?v=_JXaJ4PZMfc
https://www.youtube.com/watch?v=sGXTkRoumgk
https://www.youtube.com/watch?v=16KaFpxgqsk

Don SSDD
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Re: Rebuilding Gear Case of 48SPL

Postby Don SSDD » Fri Jan 07, 2022 2:21 pm

I’ve used DANGAR demonstrations when working on my Honda, Evinrude, and maybe a Yamaha. His presentatoin are very helpful; he explains things well and in detail.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Fri Jan 07, 2022 5:27 pm

[A youtube presentation from DANGAR MARINE] inspired me to try to bend my skeg.

I liked the 30-HP gearcase rebuild--but it is much simpler than the rebuild on the 40-48-50 models.

I learned on the old split-gearcase 30-HP engines. I could rebuild one in my sleep. I did not have a single expensive factory tool. Instead I used correct-size sockets and other home made tools. But these thru-hub gearcases are mind boggling to me.

Below is a link [to another presentation from DANGAR MARINE on the topic of HOW TO REPLACE PROPELLER SHAFT SEALS that was] suggested to me by dtmackey:

HOW TO REPLACE PROPELLER SHAFT SEALS
https://www.youtube.com/watch?v=c14ixpVXrZ0

The demonstrator circumvents the gearcase tear-down. He also warns against scratching or damaging a shaft or else the seals will fail.

[On the SPL48 engine that is the topic of this thread the propeller] shafts are grooved too badly to ignore, and that is why I am taking apart my gear case.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sun Jan 09, 2022 7:05 pm

The pinion gear bearing tools arrived.

tool.jpg
FIg. 6. Pinion bearing tool assembled to remove bearing
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IMG_0262_01_.jpg
Fig. 7. Pinion bearing tool assembled to install bearing
IMG_0262_01_.jpg (14.31 KiB) Viewed 1151 times


You use it to drive the bearing out the bottom of the driveshaft cavity into the gearcase.

My "spare-parts" gearcase had both the pinion, the forward gear, and the propshaft bearings still installed when I received it. They were very rusty so I drenched them in penetrating oil for a long time before trying to remove them. The factory service manual says if [the pinion, the forward gear, and the propshaft bearings] are removed for any reason they must be replaced.

I installed the tool and used a small machinist hammer to drive the pinion bearing down into the lower gearcase.

IMG_0263_01_.jpg
Fig. 8. Pinion bearing tool used to locate pinion bearing properly
IMG_0263_01_.jpg (28.09 KiB) Viewed 1150 times


Because the pinion bearing was very rusty it took many careful blows with the hammer.

The same tool is used to install the new bearing. The pinion bearing is only driven in one direction: from the top down, with hammer blows on the tool. Once assembled correctly, the tool is also used to locate the pinion bearing in the proper place in the cavity.

Then the retaining screw is installed in the side of the gearcase to secure it. I suppose you could use a section of pipe the correct diameter to drive the bearing. But you would first need to measure precisely the depth of the old bearing from the top of the case to locate it correctly. I am still waiting on my new pinion bearing. The correct tools to do this operation are part of a large expensive tool kit. I merely used the FSM to determine which ones were needed for a 48 hp and found those tool parts on the web as inexpensively as I could. Having the correct tools does make the job go easier.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sun Jan 09, 2022 8:19 pm

Below is the rusty old bearing as it came out on the tool.

IMG_0261_01.jpg
Fig. 9. A rusted bearing from a used gear case.
IMG_0261_01.jpg (13.29 KiB) Viewed 1140 times


This part was still in the used gearcase I bought. I would not even think of using it when I transfer the parts from my saltwater gearcase.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Wed Jan 12, 2022 2:28 pm

I finished de-greasing the parts from the freshwater gearcase. At the 20-degrees-F air temperature yesterday, there is very slow evaporation, thus minimal fumes. I had let them soak for a week in number two oil--the same as Diesel fuel. The parts came out very clean. I left the pinion and forward bearings in place as they were still serviceable.

IMG_0265.JPG
Fig. 10. All the parts from the 48hp gearcase
IMG_0265.JPG (207.3 KiB) Viewed 751 times


IMG_0267.JPG
FIg. 11. The 48SPL lower gearcase and forward bearings
IMG_0267.JPG (166.53 KiB) Viewed 751 times


IMG_0268.JPG
FIg. 12. The 48SPL upper bearing and driveshaft cavity. Pinion bearing at bottom.
IMG_0268.JPG (155.51 KiB) Viewed 751 times

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Wed Jan 12, 2022 3:56 pm

Now I can concentrate on fixing the grooves worn in the shafts where the seals ride.

The first step in fixing the grooves is to scour all the dirt and corrosion from the worn groove areas with a medium grit abrasive pad on a fast drill. You can usually see the scratches, but use your fingernail to test . You will feel a scratch that you cannot see.

Next, thoroughly de-grease the area with a product like Brake Clean that does not leave a film behind.

Cleanliness is key to the Marine-Tex adhering properly. Mix the Marine-Tex according to the directions in the box. Apply Marine-Tex to [fill] the grooves completely.

IMG_0269.JPG
Prop and drive shaft grooves filled with Marine Tex.
IMG_0269.JPG (217.11 KiB) Viewed 737 times


Don't worry about applying too much Marine Tex as you will be removing 99-percent of it. Let Marine-Tex harden at least 24-hours.

dtmackey
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Re: Rebuilding Gear Case of 48SPL

Postby dtmackey » Wed Jan 12, 2022 5:54 pm

Oldslowandugly wrote:Don't worry about applying too much as you will be removing 99% of it anyway.
It's almost as if you've seen me do drywall mudding.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Thu Jan 13, 2022 11:11 am

I've done my share of spackling and shadetree bodywork, too.

jimh
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Re: Rebuilding Gear Case of 48SPL

Postby jimh » Thu Jan 13, 2022 2:12 pm

If cured MARINE-TEX "sands like wood" as its label says, I don't think it would be a good surface for a seal to bear onto. The seal may wear away the MARINE-TEX

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Thu Jan 13, 2022 4:23 pm

Jim, regardless what the advertising says, it does NOT sand as easily as wood. If fact you would be warned not to overdo it because sanding it down by hand can be an absolute chore. I get most of it off with a Ny-lock sanding disc. Once I am close to where I need to be I polish it down with wet/dry sandpaper. On something round like a shaft you take a strip of wet/dry paper and hold the ends while you run it back and forth like you were polishing the toes of a shoe. I use this technique on automotive crankshaft dampener and rear end companion flange seals. They see a lot more usage and road debris so those seals can dig very deep grooves. On an outboard motor the dirt on the seals doesn't scratch as much, but any water intrusion is serious business.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sat Jan 15, 2022 7:07 pm

I accomplished a lot today. I sanded the Marine Tex off of the shafts with the sanding disc, then finished with the sandpaper strips. The inside prop shaft seal groove was worse than the outer groove. The inner groove was deep, wide and well defined, while the outer was shallow and inconsistent. Both grooves and some pockmarks are now filled. I then used the OMC bearing removal/install tool to pull the two rusted forward gear bearings out of the parts case. I don't see how anyone could remove them without this robust tool. OTC makes it. The puller head folds to get behind the bearings in a blind hole. Then it flips around to grab the bearing races from behind. Even with lots of penetrating oil it was a struggle to remove them. Now that all the old rusted bearings are removed from the parts case I can go about cleaning it up and repairing some damage it suffered somewhere. I am also cleaning the gasket surfaces and bearing carriers on the freshwater case for the re-build.
Attachments
IMG_0277.JPG
Bearing tool in the folded position.
IMG_0277.JPG (145.05 KiB) Viewed 349 times
IMG_0276.JPG
Bearing tool in the pulling position.
IMG_0276.JPG (150.02 KiB) Viewed 349 times
IMG_0274.JPG
Nylon sanding disc for cleaning the gasket surfaces and bearing carriers.
IMG_0274.JPG (196.41 KiB) Viewed 349 times
Last edited by Oldslowandugly on Sat Jan 15, 2022 11:21 pm, edited 2 times in total.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sat Jan 15, 2022 7:12 pm

Here is the prop shaft with the grooves rough sanded by machine and then sanded down smooth by hand.
Attachments
IMG_0270.JPG
Rough sanded by machine.
IMG_0270.JPG (163.3 KiB) Viewed 348 times
IMG_0271.JPG
Smooth finish by hand.
IMG_0271.JPG (149.66 KiB) Viewed 348 times

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Sun Jan 16, 2022 5:28 pm

This is the tool used to measure the upper bearing carrier to pinion gear distance. OMC wants to see .030" clearance. This tool is calibrated the exact distance minus the .030". You assemble the roller bearing, spacers, shims, upper bearing carrier, and properly torqued pinion gear. The tool fits exactly with a .030" blade type feeler gauge. This sets the pinion gear in the proper mesh relationship to the gears in the gearcase. It is also part of a large expensive tool kit. I found the exact gauge for my 48hp on the web for an extremely reasonable price.
Attachments
IMG_0278.JPG
Pinion gear to upper bearing carrier tool in position with a .030" feeler gauge.
IMG_0278.JPG (89.36 KiB) Viewed 292 times

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Tue Jan 18, 2022 4:41 pm

I did the thread chasing and final clean-up before starting the re-building. An amazing amount of dirt gets into the nooks and crannies while working. I can advise a simple addition to any workbench. I bolted two short sections of two-by-four to the underside of the workbench. Now the gearcase can slip into the gap and be totally supported for working on.
Attachments
IMG_0279.JPG
Gearcase wedged into wooden arms on the workbench while chasing all the threads.
IMG_0279.JPG (158.45 KiB) Viewed 39 times