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-   -   stripped thread in lower unit oil fill hole (http://www.sailnet.com/forums/gear-maintenance/97467-stripped-thread-lower-unit-oil-fill-hole.html)

suntrek 03-10-2013 09:57 PM

stripped thread in lower unit oil fill hole
 
:oI'm sure it happened to some of you... I'd over tighten oil fill bolt in lower unit in my Yahaha 9.9. Now bolt is "skipping", that means thread is stripped.
How do you regenerate it with out rethreading it for bigger size ? Problem is that hole is recesed about 3/16 and diameter just big enough to accomodate head of bolt and washer. So I' don't want to use different oil fill bolt.
Any ideas?

msmith10 03-10-2013 11:57 PM

Re: stripped thread in lower unit oil fill hole
 
If there's enough thickness in the threaded female portion of the housing you could try a helicoil. Otherwise you could drill and tap for larger bolt size then either place washers under the bolt head to fill up that 3/16 gap, or alter the head of the new plug so it fits down in the recess (grind down at machine shop or weld smaller head on plug so it matches the original). Given the usual softness of those housing castings, I think I'd take it to a machine shop and get their opinion.

suntrek 03-11-2013 12:15 AM

Re: stripped thread in lower unit oil fill hole
 
Thanks Mark!
I was thinking about the same thing, but I hoped for easy solution. There is nothing easy with this kind of stuf.

Minnewaska 03-11-2013 06:04 AM

Re: stripped thread in lower unit oil fill hole
 
I've come to like Time-Sert substantially better than heli-coil. Whichever you use, you'll need to be sure you don't leave metal shavings in the gear case from drilling out the current hole. The Time-Sert, will then return the hole to its original size/thread.

http://www.timesert.com/

sterilecuckoo58 03-11-2013 10:39 AM

Re: stripped thread in lower unit oil fill hole
 
When going to a larger bolt, consider a headless stud for Allen wrench. That would eliminate the head clearance problem in the well. But I don't know if the head is needed to secure a gasket though. On mine - well, the one I have removed and installed on a 9.9 Johnson and now retired, just had a slot in the top of the bolt/stud, there was no head, but maybe there was a seat at the bottom of the hole.

msmith10 03-11-2013 11:15 AM

Re: stripped thread in lower unit oil fill hole
 
I checked out the link, Minne. That does look like a good system.

Sea Dawg 03-11-2013 06:42 PM

Re: stripped thread in lower unit oil fill hole
 
When tapping the new threads use a blob of grease on it to capture the metal shavings.

Alex W 03-11-2013 06:47 PM

Re: stripped thread in lower unit oil fill hole
 
You can avoid this problem by sucking the oil out of the dipstick in the future (rather than using the oil drain hole). This is how the oil is changed on most inboards, but it works on outboards too.

Minnewaska 03-11-2013 08:31 PM

Re: stripped thread in lower unit oil fill hole
 
Quote:

Originally Posted by Alex W (Post 1001321)
You can avoid this problem by sucking the oil out of the dipstick in the future (rather than using the oil drain hole). This is how the oil is changed on most inboards, but it works on outboards too.

I think you are thinking of engine oil. 90w lower gear unit oil would be tough to suck out and you can't warm it up.

suntrek 03-12-2013 06:36 AM

Re: stripped thread in lower unit oil fill hole
 
Thank you all for info and tips!


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