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“Pre alpha” leak

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805HD

Regular Contributor
1975 pre alpha drive randomly started leaking gear lube from the bearing carrier at the prop shaft. The leak appears to be coming out past the main large o ring on the carrier.

Pulled carrier, found a very old and very tired O ring. Replaced that and both oil seals. Held oil for about 24 hours and started leaking again.

Pulled carrier a second time cleaned and inspected bore, looked good. Re assembled using quick silver o ring #8M0214920 and a very light coating of aviation sealant. Pressure tested at 10 PSI, held ROCK SOLID for 20 mins filled with gear lube and it’s now leaking again.

Very small leak but enough to fill the bore and make its way out and onto the ground after a few hours.

Carrier nut is seated to 150 ft/lbs

Any ideas or suggestions appreciated!
 
"""Pulled carrier a second time cleaned and inspected bore, looked good."""

What exactly is LOOKED GOOD?

I have had many drives apart, The surface for that oring corrodes-pitted and/or scale builds up.

I doubt a 1975 doesnt have some kind of crud formed where that oring seals. My 1995 Alpha one gen 1 had the same issue and the surface was ugly. The Aluminum used in 1975 is nowhere as good as newer casting materials so I would say its pitted.

I have had to severely sand that area to get it smooth and I use a TON of Perfect seal goop, Or PERMATEX 80017 AVIATION FORM-A-GASKET #3 SEALANT on the surface and the O ring.

I once did a 20 HP Johnson OB lower I had to sand then use JB weld and recreate a smooth surface thickness to allow the Oring to seal. The surface was so badly pitted.

The only other possibility is the carrier may have a crack

 
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Have you separated the upper from the lower? Obviously you have the 2 units mated during the pressure test.

Oil leaking from the bottom of the upper unit will leak down the exhaust passage and can look like it is coming from the prop shaft bearing carrier o-ring area.
 
Droid said:
Have you separated the upper from the lower? Obviously you have the 2 units mated during the pressure test.

Oil leaking from the bottom of the upper unit will leak down the exhaust passage and can look like it is coming from the prop shaft bearing carrier o-ring area.
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It’s for sure coming from behind the carrier.. I think ghost is onto something..
 
kghost said:
"""Pulled carrier a second time cleaned and inspected bore, looked good."""

What exactly is LOOKED GOOD?

I have had many drives apart, The surface for that oring corrodes-pitted and/or scale builds up.

I doubt a 1975 doesnt have some kind of crud formed where that oring seals. My 1995 Alpha one gen 1 had the same issue and the surface was ugly. The Aluminum used in 1975 is nowhere as good as newer casting materials so I would say its pitted.

I have had to severely sand that area to get it smooth and I use a TON of Perfect seal goop, Or PERMATEX 80017 AVIATION FORM-A-GASKET #3 SEALANT on the surface and the O ring.

I once did a 20 HP Johnson OB lower I had to sand then use JB weld and recreate a smooth surface thickness to allow the Oring to seal. The surface was so badly pitted.

The only other possibility is the carrier may have a crack

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Well, the surface could definitely be cleaner. I’ll pull her back apart and take a better look. I just hit it with scotch brite the picture is what it looked like before cleaning. And good to know I can be a little more aggressive with the sealant if need be.

The weird thing is, how the hell did the drive hold pressure!?
 

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805HD said:
Well, the surface could definitely be cleaner. I’ll pull her back apart and take a better look. I just hit it with scotch brite the picture is what it looked like before cleaning. And good to know I can be a little more aggressive with the sealant if need be.

The weird thing is, how the hell did the drive hold pressure!?
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The O-ring distorts and fits into the area as well as it can, but since the back edge isn't smooth, it may hold pressure for awhile, just not for long.

Use denatured Alcohol to remove the sealant, especially if it was Perfect Seal or something like the Permatex mentioned before. Be careful using abrasives in there.

Better to ensure a flat & smooth surface than assume the sealant will create the seal you need.
 
After cleaning the bore with scotch brite, a brass brush, 0000 steel wool and cleaning up with acetone and compressed air (gears protected of course) I think I got it sealed.

Had to use more permatex this time around. Just a heavier coat. Not runny or globbed on just a thicker, heavier, uniform coat to both sides of bore and carrier as well as the o ring itself.

After sitting for 10 hours I pressure tested and it’s holding air. Planning on filling it up this morning, hoping I come back from work to a clean dry drive.
 
805HD said:
After cleaning the bore with scotch brite, a brass brush, 0000 steel wool and cleaning up with acetone and compressed air (gears protected of course) I think I got it sealed.

Had to use more permatex this time around. Just a heavier coat. Not runny or globbed on just a thicker, heavier, uniform coat to both sides of bore and carrier as well as the o ring itself.

After sitting for 10 hours I pressure tested and it’s holding air. Planning on filling it up this morning, hoping I come back from work to a clean dry drive.
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A little more goop vs less is not a bad thing when Orings are invloved.
I use a LOT!
 
kghost said:
A little more goop vs less is not a bad thing when Orings are invloved.
I use a LOT!
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Yea, i hear ya! To be honest i was just kinda nervous to use it on the drive. Obviously something told me to use it as a little extra insurance but I was very conservative with it. Then per your recommendation, this time around I used a heavier amount. I hope this thing holds, I’m getting tired of chasing this leak!
 
The Merc Manuals say to use it. I did not just off the cuff decide to use it.

A service manual should have pointed this out!
 
kghost said:
The Merc Manuals say to use it. I did not just off the cuff decide to use it.

A service manual should have pointed this out!
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I just got home and still have a very tiny leak.. Son of a b!$@&

Looking at the back side of the carrier you can see a good bead of the permatex aviation sealant all the way around it. The leak is coming from the 6 o’clock position. Very tiny amount of oil, I know it’s not residual because I cleaned everything up after assembly.

What exactly do you use to seal it? A little more detail on your process would be greatly appreciated. My pos manual don’t say a thing about it!
 
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I would suggest looking closely at the large thrust washer which contacts the Oring. Maybe there is a high spot or crud not allowing it to seat properly.

This seep, Is it under pressure or not?

If not then I would suspect the carrier itself.
 
kghost said:
I would suggest looking closely at the large thrust washer which contacts the Oring. Maybe there is a high spot or crud not allowing it to seat properly.

This seep, Is it under pressure or not?

If not then I would suspect the carrier itself.
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Just to clarify, it went from leaking to just a few drops AFTER using the permatex, there’s no trails of oil leaking from anywhere else. So I think I almost got this thing.

None of this seep has been under pressure. Just static leakage from its own weight.

I drained the gear lube for the 900th time and currently have the pressure gauge on it at dead nuts 11psi. I’m going to check it every half hour and check with seals with soapy water. At this point I think collecting some data and verifying the leak is important before moving forward.

I am curious though, you said you used goop, are you talking about the actual stuff called goop or just calling something else goop? lol
 
I have both the Perfect seal and the permatex which is the same stuff and I call it goop.

Fyi, I use 14-15 psi.

There is no real specification that I have ever found. When at OMC sterndrive training, OMC had a spec of 17 psi so I adapted that minus a few PSI.

Also When I said Goop it up I meanr it
It may appear messy but it will seal and noone will ever see it..

One more thing, You may want to wait 24 hrs for the "goop" to set up.. it does harden a little. Still flexable but stiffens up
 
kghost said:
I have both the Perfect seal and the permatex which is the same stuff and I call it goop.

Fyi, I use 14-15 psi.

There is no real specification that I have ever found. When at OMC sterndrive training, OMC had a spec of 17 psi so I adapted that minus a few PSI.

Also When I said Goop it up I meanr it
It may appear messy but it will seal and noone will ever see it..

One more thing, You may want to wait 24 hrs for the "goop" to set up.. it does harden a little. Still flexable but stiffens up
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Copy that. From what I’ve gathered 15 psi is the max.

I’m coming up on 1.5 hours and still holding 11psi. Perhaps it was residual oil from assembly. I’m gonna let it ride and see what happens.

I’ll post back. As always, thank you!
 
805HD said:
Copy that. From what I’ve gathered 15 psi is the max.

I’m coming up on 1.5 hours and still holding 11psi. Perhaps it was residual oil from assembly. I’m gonna let it ride and see what happens.

I’ll post back. As always, thank you!
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15 psi is not the max. OMC developed their spec for a reason. The seals and such used in their drives whether outdrives or outboard lower units are no different then what Mercury uses......

The Mercruiser outdrive drive itself produces ~ 7-9 PSI when in operation (learned from Mercruiser training)
 
kghost said:
15 psi is not the max. OMC developed their spec for a reason. The seals and such used in their drives whether outdrives or outboard lower units are no different then what Mercury uses......

The Mercruiser outdrive drive itself produces ~ 7-9 PSI when in operation (learned from Mercruiser training)
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Oh, I was talking about Mercruiser. From what I gathered online the consensus was don’t go over 15psi.

I just landed on 11 pounds mainly cause I was scared to go higher, it held for 2 hours. I washed everything and blew it out with compressed air so it was clean and bone dry. Sat full of gear lube overnight. No sign of any leak this morning.
 
805HD said:
Oh, I was talking about Mercruiser. From what I gathered online the consensus was don’t go over 15psi.

I just landed on 11 pounds mainly cause I was scared to go higher, it held for 2 hours. I washed everything and blew it out with compressed air so it was clean and bone dry. Sat full of gear lube overnight. No sign of any leak this morning.
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You won't blow it up if you use higher pressure- look at the diagrams for the drive- it's not going to bypass a paper gasket and if it causes leaking through O-rings and oil seals, it may be time to replace those because they don't last forever.

When the bearing carrier was out of the lower gearcase, did you clean it thoroughly and inspect it for damage?
 
jimn said:
You won't blow it up if you use higher pressure- look at the diagrams for the drive- it's not going to bypass a paper gasket and if it causes leaking through O-rings and oil seals, it may be time to replace those because they don't last forever.

When the bearing carrier was out of the lower gearcase, did you clean it thoroughly and inspect it for damage?
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The drive was recently off the boat. Replaced the whole impeller housing including the base plate. Also did the shift shaft bushing. Didn’t go any further than that or even look at the condition of the carrier.

When the carrier leak happened I noticed the outer prop shaft seal looked like it served a hard tour in Nam so I replaced both of them.

The last repair, which now seems to be holding, I did clean and inspect the inside of the carrier bore with emphasis on the “mating surface” where the o ring rests. Some crud but no deep nicks or pitting..

The “goop” appears to be doing its job, but I agree with you. There’s a definite reason it was leaking…
 
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