Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Oldslowandugly
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Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Fri Jan 21, 2022 9:09 pm

[I combined another thread on the topic of gear case rebuilding into this thread on the same topic--jimh]

[The original thread containing these posts already had over 40 illustrations and remains available as Rebuilding Gear Case of 48SPL-Part 1. Threads with so many images are difficult to load for readers with slow and intermittent internet connections, which apparently included the author's internet connection, I have split the thread into two parts to reduce the loading time and minimize the problem with images failing to load for some readers.--jimh]


I am re-building my 1996 Evinrude 48SPL gearcase. The propeller shaft bearing carrier has seals at the outer end.

Image
A double-lipped seal

Image
A single-lip seal

I found that use of two single-lipped seals (that used to be installed back to back) has been superseded by one double-lipped seal.

I was able to install the new type seal deeper into the seal cavity. That gave the the seal surfaces fresh metal to ride on. There is room to add another of the original single-lipped seals on top of the new double-lipped seals. At surfaces of a new seal would ride at the outermost part of the seal cavity and still be on the correct part of the propeller shaft.

IMG_0288.JPG
Fig. 48. A new double-lipped seal has been installed. There is room for another single-lipped seal.
IMG_0288.JPG (155.28 KiB) Viewed 2557 times


Is an extra seal beneficial or detrimental to the other seals?

MarkCz
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Re: Add Extra Propeller Shaft Seal

Postby MarkCz » Sat Jan 22, 2022 6:01 am

What lubricates the seal-to-shaft interface as the shaft spins?

For the inner seal would imagine gear oil be the lubricant?

For the outer seal would water be the lubricant?

Oldslowandugly
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Re: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sat Jan 22, 2022 8:57 am

For the outer seal would the lubricant is water. The pressure of the fluid seawater would press the seal lip against the shaft. I read that the open side of the seal faces the seawater for this reason, however, I am no expert at seal operation.

The factory service manual instructs for the installation of two separate seals in the original design, and to pack the space between the two seals with OMC Triple Guard grease

The outermost seal would take the brunt of the force trying to push water into the gear case. Any water that intruded past the outer seal would encounter the grease and then the second seal.

Someone suggested that since the inner seal would not see either oil or water then it may starve for lubrication. It would get hot, the grease would melt and leak away, and the non-lubricated seal would probably fail.

Oldslowandugly
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Rebuilding Gear Case of 48SPL-Part 2

Postby Oldslowandugly » Thu Feb 24, 2022 8:53 pm

With the carrier seals in place and working I can finally place the carrier into the gearcase and seal it up. I removed the propshaft again to clean inside. I had to wirebrush the remains of the cured Ultra Black from the inside of the case. It comes off very easily by using a wire brush on a long shaft and an electric drill. Then flush out the debris with solvent.

fig42a.jpg
Fig. 42. Wire brush on gear case (out of focus).
fig42a.jpg (21.72 KiB) Viewed 2055 times


Figure 43 shows is the clean gearcase ready for the carrier. See the ledge inside? That is what makes it hard to get the O-ring part past it.

fig43a.jpg
Fig. 43. A clean gearcase ready for assembly.
fig43a.jpg (51.33 KiB) Viewed 2055 times


Don't try to insert the propshaft without removing the shifter rod. You will never get the shifter pivot fingers into the slots in the shifter cradle. Open the shifter rod seal carrier up top again. It is only sealed with Triple Guard grease so no harm done. Place the shifter cradle on the shifter dog end of the propshaft and retain with the OMC needle bearing grease. Insert the propshaft until the cradle just pokes through into the shifter cavity. Then you drop the shifter rod and pivot down to engage the slots in the cradle. You MUST look in with a flashlight to see what you are doing to get it right.

fig44a.jpg
Fig. 44. The arrangement inside inside the gearcase. The pivot arms must engage the cradle slots. (Out of focus.)
fig44a.jpg (11.28 KiB) Viewed 2055 times



Once that is done you insert the pivot screw through side of the case and through the holes in the pivot and tighten to the [undescribed] specified torque.

Use Lok-Tite on the screw threads, and use sealer on the screw shaft.

If you did it right you can shift the gears with the shifter rod and the propshaft can't be removed.

Then I placed the reverse gear and thrust bearing into the case. The thrust washer goes back on the inner carrier face. The thrust bearing and washer are held in place with the OMC needle bearing grease.

Now the carrier can be inserted. Again, I coated the O-ring, its groove, and both flanges with Ultra Black sealer to prevent leaks and corrosion.

As before, use the long extractor screws to grab the carrier and insert it with the drain hole at the bottom.

Then I used a length of PVC pipe and a woodworking clamp to drive the carrier all the way in. Two carrier retainers are installed and retainer screws tightened to [undescribed torque] specifications.

Now that the gear case is back together, I must wait 24 hours for the Ultra Black to cure. Then I can test for leaks.
Last edited by Oldslowandugly on Thu Feb 24, 2022 9:03 pm, edited 1 time in total.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Thu Feb 24, 2022 9:00 pm

fig45a.jpg
Fig. 45. The gear case after reassembly.
fig45a.jpg (55.28 KiB) Viewed 2051 times


The Ultra Black must be allowed to cure for 24-hours. I will give the Ultra Black a longer during time because of the large carrier flange surface I coated.

Do not pressurize the case for a test and blow out uncured sealer.

That would ruin all your work and require rebuilding it all over again.

Oldslowandugly
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Re: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Thu Feb 24, 2022 9:10 pm

Update: either the new double-lipped seal is not worthy or perhaps I failed at installing it. Either way, when tested it leaked air terribly. I removed it and purchased two new single-lipped seals. I installed them back-to-back as per the factory manual. When tested they held air nicely.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL

Postby Oldslowandugly » Fri Feb 25, 2022 10:08 pm

While waiting for the Ultra Black to cure I turned my attention to the parts gearcase.

The front of the cavitation plate suffered a big bend and cracked on both sides. I wanted to try the aluminum brazing technique I see in videos. I took my grinder and cleaned off the area along the crack and found it was pretty bad. Just doing that made it break off completely.

fig46a.jpg
Fig. 46. Touching the anti-ventilation plate with a grinder caused a portion of it to break off.
fig46a.jpg (41.85 KiB) Viewed 2049 times



After cleaning the crack I clamped the broken piece to the plate.

fig47a.jpg
Fig. 47. The broken segment was clamped in place for possible re-welding.
fig47a.jpg (33.78 KiB) Viewed 2049 times


I tried to braze the two pieces of the anti-ventilation plate back together with some 4043 TIG rods. I found that a blowtorch was not sufficient to melt the TIG rod. Research showed the 4043 rod melted at around 1000-degrees-F, which is too hot for this technique. The correct aluminum welding rods [unspecified] for this application will melt at around 600 to 700-degrees-F.

You might be tempted to try an oxy-acetylene torch but that would surely melt the gearcase itself.

I will ask my welder friend to TIG weld this for me.

jimh
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Re: Rebuilding Gear Case of 48SPL-Part 2

Postby jimh » Sun Feb 27, 2022 11:27 am

Congratulations on the reassembly of the gear case. I have been reading your articles carefully, and I have six questions for you.

Have you pressure-tested the gear case seals after your latest final assembly?

If you have pressure-tested the gear case, what is the recommended maximum pressure in PSI to use in the test?

What is the specified torque for tightening the several fasteners you have mentioned that you tightened to a specified force?

After using a wire brush on the inside face of the gear case bullet, would repainting that surface be a good idea to prevent corrosion?

At the factory, would the gear case only be painted after it was completely assembled?

Or, at the factory would the gear case casting be completely painted before the internal components were assembled into its cavity?

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sun Feb 27, 2022 4:34 pm

jimh wrote:Have you pressure-tested the gear case seals after your latest final assembly?
Yes, I pressure and vacuum tested the case after giving the sealer three days to cure.

jimh wrote:....what is the recommended maximum pressure in PSI to use in the test?
The manual suggests 3 to 6-PSI initially and then check if that pressure holds. If not, then submerge the gear case in water and look for leaks.

If 3 to 6-PSI pressure is held, then increase to 16 to 18-PSI. If the seals holds you are good to go. If not submerge and look for leaks, and Repair as necessary. I used a bicycle pump that has a gauge to test with. The pump gauge was easiest to read at 20-PSI so I went used that value. My repaired gear case held that pressure.

The gearcase must hold against both oil pressure inside and water pressure outside and that is why the double seals are used.

You must also test with a vacuum source such as a Mityvac tool. I used a Mityvac adapter to screw into the drain hole with a bit of OMC Roller Bearing grease to eliminate a leak at the drain hole threads.

fig49aa.jpg
Fig. 49. MityVac tool showing 15-inch vacuum.
fig49aa.jpg (33.95 KiB) Viewed 1978 times


First, create a vacuum of minus 3 to 5-inches; see if it holds. If yes, then increase the vacuum to 15-inches.

If the seals leak at either test, squirt oil around each seal to find the leak. Repair as necessary.

Gearcase seals held vacuum at 15 inches just fine.

After passing the pressure and vacuum tests now I can install the rest of the parts.

I used a home-made pressure tester that consists of a short length of plastic hose that is clamped onto the end of a regular tire schrader valve. I screw the plastic hose into the gearcase drain hole.

Fig50a.jpg
Fig. 50. Home-made pressure adaptor.
Fig50a.jpg (14.69 KiB) Viewed 1978 times


jimh wrote:At the factory, would the gear case only be painted after it was completely assembled?

Or, at the factory would the gear case casting be completely painted before the internal components were assembled into its cavity?
I found no trace of paint anywhere inside the gearcase. I think it was assembled bare and the outside painted afterward. That is why I used sealer on the bearing carrier flanges to protect against corrosion.

The saltwater gear case I had to cut open was severely corroded on the inside.
Last edited by Oldslowandugly on Sun Feb 27, 2022 5:20 pm, edited 1 time in total.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sun Feb 27, 2022 5:00 pm

Now that the case has passed the seal tests I can finish installing the rest of the parts.

I replaced all fasteners with marine grade stainless steel fasteners. I also use anti-seize on all threads.

NEW PROJECT: WATER PUMP SERVICE

The water pump service used a a new impeller and new seals. The pump housing and plate were in perfect condition so I re-used those parts.

I use Ultra Black to seal a new gasket to the case and the impeller plate.

Fig51a.jpg
Fig. 51. Impeller plate and new gasket in place.
Fig51a.jpg (30.12 KiB) Viewed 1976 times


When inserting the impeller, oil the housing lightly and twist the impeller in counter-clockwise. The open side of the cam groove must face you. Make sure all three vanes are bent in the correct direction.

Add the driveshaft grommet to the top of the housing and seal with OMC Adhesive-M or 3M847.

The formed O-ring goes into the groove, and I seal it with some Ultra Black.

Fig52a.jpg
Fig. 52. Pump impeller and O-ring in place. Ultra Black sealer on housing face.
Fig52a.jpg (41.68 KiB) Viewed 1976 times


[MODERATOR'S NOTE: In Figure 52 the impeller looks like it was turned COUNTER-CLOCKWISE. Please clarify.] The answer is that you are looking at the impeller housing from the bottom. In the installed position it will be CLOCKWISE.

The impeller cam gets placed into the flat on the driveshaft and held in place with some OMC Roller Bearing grease. The sharp edge of the cam points in the direction of driveshaft rotation [clockwise].

Fig53a.jpg
Fig. 53. Impeller cam held in driveshaft flat with grease and pointing clockwise.
Fig53a.jpg (28.5 KiB) Viewed 1976 times


Try to position the impeller in the housing so that when you drop the pump housing down the driveshaft the impeller groove and the cam are aligned as closely as possible. In this way they will slide right into place with no drama. Make absolutely sure the driveshaft cam has engaged the impeller. If you look through the water tube hole you can just see the impeller pass by as you turn the driveshaft.
Last edited by Oldslowandugly on Mon Feb 28, 2022 11:23 am, edited 3 times in total.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Water Pump

Postby Oldslowandugly » Sun Feb 27, 2022 5:17 pm

Once you are sure the impeller will turn with the driveshaft you can insert the stainless housing bolts into the holes that have been coated with anti-seize. Tighten the bolds with torque wrench and to the specified torque. [Moderator's note: here is a good place to insert the actual torque value.] If you strip these bolt holes the pump will leak.

Fig54a.jpg
Fig. 54. Torque wrench used to tighten housing bolts.
Fig54a.jpg (24.22 KiB) Viewed 1974 times




The water tube seal goes onto the housing dry with no sealer.
Fig55a.jpg
Fig. 55. Completed water pump.
Fig55a.jpg (22.46 KiB) Viewed 1974 times

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sun Feb 27, 2022 5:39 pm

Next the propshaft sacrificial zinc anode goes on. If your anode looks like the one on the right side- replace with a new one like on the left side.

Fig56a.jpg
Fig. 56. New anode (left) and worn out anode.
Fig56a.jpg (22.62 KiB) Viewed 1973 times


The anode slips down the propshaft and two small stainless bolts secure the anode to the propshaft bearing carrier. Torque to specs.

Fig57a.jpg
Fig. 57. New sacrificial anode in place
Fig57a.jpg (35.47 KiB) Viewed 1973 times


Next I replaced the water inlet screens on the sides of the gearcase. I also adjusted the shifter shaft depth as described at the beginning of the thread. You screw the shaft in until it bottoms. Then you unscrew it the number of turns you recorded at the beginning. The bent end of the shaft ends up pointing forward.

I filled the gearcase with clean used OMC Hi-Vis gearcase lube.

FIg58a.jpg
Fig. 58. OMC pump filling gearcase with clean used lube.
FIg58a.jpg (18.19 KiB) Viewed 1973 times


When I test the motor in a barrel of water I want the used oil to grab any dirt or debris that may remain inside from the rebuilding. After the motor gets to operating temps and there are no leaks or expensive noises I will drain it and re-fill with new oil. The final repair will be those chips missing from the skeg.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sun Feb 27, 2022 6:01 pm

At this point the used fresh water gear case is finished.

SOME FINAL REMARKS ON THE PROJECT

The gear case came apart fairly easy with simple tools.

A common automotive steering wheel puller can extract the propeller shaft bearing carrier if it is not badly corroded and stuck in the case.

I used the OMC puller tool to remove the upper driveshaft bearing carrier but it was not stuck. I think a common slide hammer would have gotten it out.

Because I left all the bearings in place, there was no need for any expensive tools to remove them.

The saltwater gearcase is another matter. It was so badly corroded I had to cut it open to salvage the parts. Later I found a spare gearcase to use for a rebuild using those parts.

Later I will continue with that rebuild as it involves more procedures.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Sun Feb 27, 2022 7:01 pm

Torque fasteners specifications for Evinrude 40, 48, 50-HP engines
All units in inch-pounds unless noted otherwise
    Water pump screws: 60 to 84
    Oil level and fill drain plugs: 60 to 84
    Gearcase retaining screws 3/8": 18 to 20 foot-lbs
    Gearcase retaining screws 7/16": 28 to 30 foot-lbs
    Propeller shaft bearing housing screws: 120 to 144
    Upper Driveshaft bearing housing screws: 14 to 16 foot-lbs
    Shift rod cover screws: 60 to 84
    Pinion nut: 40 to 45 foot-lbs
    Pinion bearing retainer screw: 48 to 80
    Anode to propeller housing screws: 108 to 132
    Trim tab screw: 216 to 240
    Shift rod bushing: 48 to 60
    Shift rod pivot screw: 48 to 80

Shift Rod Height
These distances are from the top of the gearcase to the hole at the top of the shifter shaft with the bend facing forward.
    Standard shaft: 16 and 15/16-inch ± 1/32-inch
    Long shaft: 21 and 15/16-inch ± 1/32-inch
    Extra long shaft: 24 and 7/16-inch ±1/32-inch

REMINDER: There is an expensive tool that [can be used to set the shift rod height]. [To avoid having to use the expensive tool, before disassembly of the gear case] measure and record the screw turns to bottom out the shift shaft before unscrewing it for removal. The length is critical; once the gearcase is re-attached to the engine, the neutral shift position detent relies on the shifter shaft position to be correct.

jimh
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby jimh » Mon Feb 28, 2022 10:35 am

Thanks for this lengthy article with its 56 illustrations. I know how difficult it can be to take photographs while you are performing work on a repair. You did a nice job with grabbing images at each step. You appear to have restored this rather old, well-used, and slightly damaged gear case to a useful condition.

I hope the repaired gear case holds up well for you. Perhaps in six months you can revive this thread to let readers know the final outcome of the repairs.

This article about the Evinrude 48SPL will be useful to readers who also have that exact engine, and others who are contemplating undertaking a repair of a different engine may find this long thread a useful introduction to the many problems that may lie ahead for them when renovation of a rather old outboard engine gear case is being contemplated.

Oldslowandugly
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Re: Rebuilding Gear Case of 48SPL-Part 2: Add Extra Propeller Shaft Seal

Postby Oldslowandugly » Mon Feb 28, 2022 11:12 am

Thanks Jim. While this repair concentrated on the 1993 to 2005 Evinrude 40, 48, and 50-HP engines, the procedures are common to earlier and different displacement motors as well.

I was afraid to take this job on because of the special tools and measurements required. I have the factory service manual and I found it indispensable. Not only does it explain all the step-by-step procedures but it identifies the tools required. It is available in printed form from various vendors as well as in PDF form on websites that post owner and repair manuals.

I found most of the tools needed for sale online, and I was able to adapt other common tools for various tasks. I wanted to show that a lower unit that was not damaged or hopelessly corroded could be rebuilt by the average DIY mechanic.

Most of the repair parts are easily available. While none of the parts or tools are inexpensive, the current cost of a commercially rebuilt lower unit far exceeds this investment.

As for the badly corroded unit I will continue with the overhaul and post my results.