Problem with Lower Unit Plug

[73SCTsunami]

The plug in the lower unit of my new to me 1996 225hp Merc is frozen in pretty well. I've tried everything I can think of to get it out with no luck. My next step is to bring it to a buddies welding shop to weld on a nut, or since there's a hole from my failed attempts with an extractor, maybe a bolt. Along those lines, I'm wondering what the plug is made out of so I know what I can weld to it. Does any one know what kind of metal the plug is made of?

On the same topic, I've been advised that once these things get stuck, there's not much you can do but run it on the existing oil until it fails and tehn replace the whole foot. I'd hate to go that route. I thought that maybe I could drill this one out fill the old hole and then tap one for a new plug but have been told the casting is too thin to tap a hole. Has anyone tried this? If it's so thin, how'd they tap the first hole?

I'd aprreciate any advice.

Thanks,
Jon

 

[Silvertip]

Re: Problem with Lower Unit Plug

Trying to weld anything onto the plug will likely melt the aluminum around it rendering the lower unit useless. You should have used an impact driver the very minute the plug wouldn't come out. If the slot is not buggered up too bad that's still an option. Buy a replacement plug and measure the diameter of the threaded area. Then continue drilling (one drill size at a time) until you have the hole slightly smaller than the thread diamter. I'm guessing this will be about 5/16-inch. Buy a left hand thread tap and bolt and nut to match. Tap the hole. Put the nut on the bolt. Thread the bolt into the plug, and tighten the nut. You can now use a wrench to remove the plug. Again, if you have an impact wrench (electric or air), the plug should come loose easily. Make sure the nut is very tight so the bolt dosn't spin into the housing so far it damages internal parts. If you have access to a welder, position the nut as required and weld it to the bolt so it acts as a stop.

 

[73SCTsunami]

Re: Problem with Lower Unit Plug

Unfortunately, I don't have any air tools and was really trying to avoid trailering this thing to my buddy's welding shop where there are air tools. You can see how well that's worked out so far. Lesson learned...again.

At any rate thanks, alot for the idea on tapping the plug that's in place with reverse threads. I may actually try that before trailering it up there since I can do that at home. It will definitely be tight considering the size of the plug and the hole already in it from trying an extractor.

I'd still love to find out what that plug is made out of if any one knows.

Thanks again. I won't have a chance to try it until the weekend but that's a great idea. I'm kicking myself for not trying it before.

 

[DHPMARINE]

Re: Problem with Lower Unit Plug

The plug is stainless steel.Drilling,tapping and other machining may be difficult.

Snap On Tool makes an impact driver you put a bit in (in your case a slotted screwdriver bit) and as you turn it in the direction you need (off or on) you hit the tool with a hammer.Works great.Have had two lower units it failed on,since 1978.Those we did junk.

I would go this route before I did any more drilling.IF you have any slot left on the screw.Filling the slot with valve grind compound first may help.It works wonders with phillips head screws.

DHP

 

[Rex]

Re: Problem with Lower Unit Plug

If you drill it the way you our talking about have the
TAP ready and you can cleean the theads right up.
I'm toolmaker and have done this before.
I think it a 3/8-16 but check on that very important.

Rex or Rexh1954

P.S. It been about a year since I was on last.
Got to get user Right.

 

[Silvertip]

Re: Problem with Lower Unit Plug

73 -- The impact driver I'm talking about is not an air tool. It's a hand-held device that you can insert various driver bits (flat, phillips, torx, etc.) into. You strike the end of the tool which causes a twisting force (either tighten or loosen). It works like and impact wrench but a hammer is used for power. These are dirt cheap and any discount tool store. Visit a pawn shop and you'll probably find all sorts of them for a couple of bucks. If the slot is messed up, use a dremel tool to cut a new slot.

 

[73SCTsunami]

Re: Problem with Lower Unit Plug

I'm surprised to hear it's stainless. The extractor, really seemed to just bore in to it so I would have thought something softer. Drill bits had no trouble either until stopping cold at the back of the magnet.

I understand about the impact driver. I just don't have one and there's only one store near me that might. I'll check their first and if it's reasonably price wise will try that first. Otherwise, I'm gonna stop messing around and bring it up to my buddy's shop. There's actually a decent chance that he'd have it there and I caould kill hours driving around town looking for it.

Thanks for a ll the advice guys. If you have any more, I'm all ears. Otherwise, I'll report back on Monday with how these ideas worked out.

Thanks again,

Jon

 

[gss036]

Re: Problem with Lower Unit Plug

Try Sears store, they used to carry them, I have one laying on my bench.

 

[casi77]

Re: Problem with Lower Unit Plug

i had used a screw extractor similar to this one with success:

http://www.northerntool.com/webapp/...ne&fullTime=none&totalSounds=none&rotate=none

 

[davebad22]

Re: Problem with Lower Unit Plug

I would give the screw extractor a try. Here is another place to get one.
http://www.acehardware.com/product/...geBucket=0&parentPage=family&searchId=1304507
Sears should have them also.
Here is a page with things to try.
http://www.motorcycle.com/mo/mcnuts/stuckscrews.html

 

[Silvertip]

Re: Problem with Lower Unit Plug

The magnet has stopped the drill bit. Going any further might just drop the magnet into the lower unit which will immediately cause it to attach itself to the steel gears. Getting it out without disassembling the lower unit may be tricky. In my view the impact driver is still the least expensive and most practical solution at this point.

 

[73SCTsunami]

Re: Problem with Lower Unit Plug

The motorcycle article seem to imply that impact driver was only for philips. I hope that's not true. I'm gonna see if I can find one tomorrow morning. Unfortunately the nearest sears is about 45 minutes away.

The extractor that I used was the one from Ace in the above link and didn't work at all, It just drilled out more material. I don't have any like the ones in the Northern Tool link but, I may invest in a set while I'm looking for the impact driver.

 

[sport15]

Re: Problem with Lower Unit Plug

Care with a shot of heat from a small propane torch might help too. Care must be taken to not get things to hot and cook the paint and bearing seals by the wheel..

 

[Silvertip]

Re: Problem with Lower Unit Plug

When you look for a impact driver, make sure it comes with a "large" flat bit. If it doesn't, check the hardware section as the attachments are square or hex drive and you may be able to find a flat bit there. I would avoid the heat for now. If a couple of wraps with the impact tool doesn't loosen it, then its time for drastic measures.

 

[diaric]

Re: Problem with Lower Unit Plug

this is what the impact driver is, available at most hardware stores and work very well.
http://www.acehardware.com/product/...driver&parentPage=search&searchId=19228849932

 

[73SCTsunami]

Re: Problem with Lower Unit Plug

While picking up the impact driver Saturday morning I got a better extractor too. 4 cornered bades rather than reverse threads. Two raps from the hammer to seat it and then the vise grips turned it out with no problem. Thanks for all the advice. never had to resort to the impact driver. I'll have to decide if I should keep or return it now. Just afraid that if I keep it, it will get lost in the garage clutter.

 

[gss036]

Re: Problem with Lower Unit Plug

Thanks for the up date, I think you should keep it. I have had mine for over 25 years and do use it on occasion.

 

[jddenham]

Re: Problem with Lower Unit Plug

I'll have to decide if I should keep or return it now. Just afraid that if I keep it, it will get lost in the garage clutter.

Did you rent it??

 

[joblo33]

Re: Problem with Lower Unit Plug

Keep it. Whenever you take a lower unit plug out, whether you think it's stuck or not, use the impact driver. It will save you from this situation again as it wont screw up the slot. In the outboard shop I work for we use the impact driver every single time just to save from a lot of hassle and wated time.
Eric

 

[Texasmark]

Re: Problem with Lower Unit Plug

Me too on the impact driver. Priceless for this type of a problem.

Test it before you use it to make sure you have it set to deflect the proper direction and make sure it is lubed up so it can turn easily when you whack it.

The nice thing about the blades, besides being strong, is that the sides are parallel, not tapered like most regular screw drivers and this really helps it to grip. I think it's absolutely stupid to taper the tips of flat balde screwdrivers. Would be a lot fewer damaged screws in the world if they didn't take the easy way out.

Good luck,

Mark