Lower unit oil drain plug repair
 

Hi everyone,

I did a search first, came up empty. Here's the problem: I have damaged threads on the lower unit oil drain plug. No water intrusion yet, but I'm fixing it this winter. My plan is to drill a bigger hole and insert a helicoil.

Here's the questions: 1) is the helicoil the best option? and if so 2) Do I need to remove the gearcase housing/gears to prevent aluminum shavings from causing problems?

I'm not sure how many parts I need to remove from the lower unit. I do have a shop manual (Johnson OMC, not a Clymers). Removing the gearcase seems straightfoward enough, but then it gets beyond my comfort zone. Removing gears and driveshafts reads like it's a lot of work, plus requiring a lot of specialty tools. I do have a 2-prong gear puller and a gear puller set from Harbor Freight.

Thanks for any feedback.

is there any way to take a tap & clean up the threads you have?

smear grease on your tap, it will catch the chips when you are tapping new threads, try cleaning up the existing threads first. Is it the upper or lower drain plug?

Whadda great tip!...little ideas like this make a job SO much easier:clap:

Ah! Like axle/bearing grease out of a grease gun? That seems like it ought to work pretty well. How bad would it be if a small chip fell in the gear case despite the grease?

It's the lower lower drain plug?

yes, just any kind of thick gooy grease, thread it in, take about two or three turns, pull it back out, wipe the grease off, then do it again, each time adding grease and threading it in further. If you have an air compressor, have some one blow air into the upper vent hole while you are threading the hole, the air will blow any chips out(wear safety glasses while doing this)

Excellent! I appreciate all the advice. I have a HeliCoil repair kit on order. Supposed to arrive next Wednesday. Will provide a write-up if anyone is interested.

I've done this a few times... I chose the second method using compressed air.

success!
 

I know this thread is a little stale, but I just wanted to say that the grease and air compressor trick worked like a champ. I ended up having to drill out what was left of the existing threads to install the HeliCoil; I used grease on the bit, drilled a little, blew out any chips the grease did not catch, and repeated until done. Tapping the hole was done using the same steps. The air compressor works great to clean off the chips on the drill and tap, too.

Anyway, it worked great. Thanks!

Cool, good tips in this thread.