# Help with stripped lower unit threads



## D-Bak (Jul 8, 2014)

Just bought a 2006 Johnson 9.9 and was getting ready to take it out for the maiden voyage and decided to change lower unit oil. Chocolate milk. I then examined the lower bolt and noticed that the threads were stripped out pretty bad. The steel bolt was lined with the aluminum threads of the case assembly.

Obviously my day is ruined. I began looking up some ways to fix this, one of them being new unit case. Turns out those are almost non existant and the only one I found was $1,800 bucks. (engine model J10RSDC)

Two questions. 

1) What experience do you guys have in fixing something like this? What works best?

2) If all hell breaks loose and I end up going with the worst case scenario (in my mind that is JB aqua welding the lower bolt into place) would I be able to fill the lower unit from the top bolt hole? Obviously I would think it would take much longer as I would need to make sure all air is out of the system, but with a new casing costing $1,800 bucks I am willing to do just about anything.

Any advice is greatly appreciated.

Thanks gents.


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## jfarkas (Apr 14, 2008)

Im assuming your talking about the lower screw that you take out to drain the oil? I would call ahead to see if someone will rethread that hole a little bigger and use the appropriate screw with washer.


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## D-Bak (Jul 8, 2014)

Yes that is the one that is stripped. Looks like the previous owner cross threaded the heck out of it when he put it in last. Won't even seal properly now...


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## brent k (Nov 10, 2013)

You tube heli coil it might be an ok fix. They can be tricky to install tho. Another thing is to try calling a machine shop and see if they will drill and tap the hole for the next size plug for you.


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## brent k (Nov 10, 2013)

If you like another option is i can pm you the number to a guy i deal with for parts. I can pm you his number if you like. He is located in reynoldsburg. Hes pretty clever especially with small outboards and always treats me fair.


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## whjr15 (Jun 16, 2005)

D-Bak said:


> Just bought a 2006 Johnson 9.9 and was getting ready to take it out for the maiden voyage and decided to change lower unit oil. Chocolate milk. I then examined the lower bolt and noticed that the threads were stripped out pretty bad. The steel bolt was lined with the aluminum threads of the case assembly.
> 
> Obviously my day is ruined. I began looking up some ways to fix this, one of them being new unit case. Turns out those are almost non existant and the only one I found was $1,800 bucks. (engine model J10RSDC)
> 
> ...


Maybe, if all else fails, you could tap the hole to the next size larger, replace it with another bolt and find an appropriate sized o-ring and/or gasket material to seal it? You would, most likely, have to do all of your own oil changes from there out--since you will have to Frankenstein a filling system together too!

Not really sure what you would do to remedy that situation... Just throwing it out there in case it sparks some ideas for ya! Curious to see everyone else's answers too , you can't be the only one to ever have this happen!! Good luck!

Edit: got sidetracked typing my reply, and didn't see that anyone had replied before me!


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## brent k (Nov 10, 2013)

Pm sent to op


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## slimdaddy45 (Aug 27, 2007)

I bought a bottom end for my motor off of ebay and the bottom plug was also stripped this on a 115 Johnson so I drilled and put a helicoil in it works fine no leaks been that way for 4 yrs no and not a problem


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## Lewis (Apr 5, 2004)

Helicoil or you could drill and tap for a small pipe plug and use a socket head (allen type) pipe plug.
If you use a helicoil, clean the newly tapped threads of all traces of oil using carb cleaner. Use Loctite on the helicoil. Not on your new plug.


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## D-Bak (Jul 8, 2014)

Lewis said:


> Helicoil or you could drill and tap for a small pipe plug and use a socket head (allen type) pipe plug.
> 
> If you use a helicoil, clean the newly tapped threads of all traces of oil using carb cleaner. Use Loctite on the helicoil. Not on your new plug.



I have read a few places that the helicoil does not seal well enough to be water tight. I am assuming the loctite will solve this problem if enough is used to coat the entire coil insert and allowed to cure?


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## ohiojmj (Apr 16, 2004)

D-Bak said:


> I have read a few places that the helicoil does not seal well enough to be water tight. I am assuming the loctite will solve this problem if enough is used to coat the entire coil insert and allowed to cure?


Heli-Coil threads do not seal against tapped female threads in the lower unit. You will rely on the gasket or o-ring for sealing and the threaded joint to maintain preload. Loctite will help keep the Heli-Coil from backing out when removing plug.

http://www.stanleyengineeredfastening.com/brands/heli-coil


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## Lewis (Apr 5, 2004)

Ohiojmj is correct. The sealing takes place with the gasket or o ring at the top of the plug. Loctite will work but, if you want to make absolutely sure there are no leaks, I would use JB Weld epoxy on the helicoil instead of locktite. 32 years as a machinist here..lol This method will work just fine. Just make sure you use an oil based lubricant on the helicoil drill and tap to prevent galling of the aluminum. Remove all traces of this oil with carb cleaner or solvent prior to installing helicoil. 
Make sure to install the helicoil flush or slightly below the sealing surface.
Let the JB Weld cure before installing new plug and gasket. Don't overtighten.


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## bountyhunter (Apr 28, 2004)

I have one with your problem ,put it back together good and tigh, seal over with jb weld or marine silicone. then fill from the top . I use a squeeze blub and small hose ,heat the oil it goes in pretty quick.


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## Bad Bub (Jan 17, 2006)

bountyhunter said:


> I have one with your problem ,put it back together good and tigh, seal over with jb weld or marine silicone. then fill from the top . I use a squeeze blub and small hose ,heat the oil it goes in pretty quick.


How do you drain it next time?


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## hupcej4x4x454 (Oct 7, 2014)

I've had very good results repairing stripped threads in hydraulic systems with this style EZ Loc thread insert...
http://www.mcmaster.com/#standard-threaded-inserts/=wmn0uw
They're more robust than wire heli-coil inserts, and are better suited for fluid sealing and pressurized applications. 
Place a sealing washer like these under your new plug bolt's head, and you'll be good to go...
http://www.mcmaster.com/#standard-washers/=wmn4kf
Good luck!


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