Leaking LU fill plug and A nick in the plug

[Paintworx]

I just picked up a Ranger with a 06 250 HPDI and I noticed that oil was seeping out of the fill plug on the Lower unit. When I pulled it out to inspect i noticed the threads felt soft and low and behold the case Is stripped. I also noticed that the magnetic plug has a little nick in it like something hit it. I have read that guys are replacing the plug with a mercury plug and tapping to the next size up. Not sure if this is a repair for upper plug or lower but mine is the upper plug.

[Tx Champ]

If you tap to a larger size, I would think you'd take a chance on getting cuttings into the LU if you didn't drain, remove and possibly disassemble it. What about a helicoil? You'd still have to make sure you washed any shavings out, but you could go back with the original threads.

[Paintworx]

I think a heli coil could leak around the insert? And would be more messy as far as shavings. I a bummed about any of the options since I have not even used the boat. Better than having it fall out and fill with water I guess.

[jdwo2212]

Depending on how good you are with lower units you could probably do it yourself. Any reputable shop can do it quickly. Retap, drain, refill. Should be about $100 job. Good that you noticed it before you fluid ran low.

[Paintworx]

I ended up drilling and re tapping to 3/8” and used a mercury lower plug (without the magnet). There is a part of the casing in there that blocks the longer magnet plug. The merc part works perfectly and seems more stout than the Yamaha part. I dabbed some grease inside the hole to catch the shavings as I drilled. I went slow and made sure the shavings came outward and did little cuts and cleaned as I went. After I got it drilled I put grease on the tap and it captured the shavings nicely. I don’t have the magnetic plug though now but better than leaking (or worse). I drained the oil and notice that it’s kinda milky orange in color. Probably had some water in there.
I have some merc gear oil change was gonna put in there and drain after I run it once. What should I be running in the 250 Yamaha lower unit after I dump the merc stuff?

[201pro]

Merc High Perf LU fluid would be fine. I have used it for years.

[Jer]

I had this happen to my lower drain screw on a 07 hpdi 200. I retapped for the larger size mercury plug. has been like that for 6 years now and still working just fine. I did not have any issues with shavings...drained and refilled a couple times.