Lower Unit Drain Plug

Mike Langianese · Sep 16, 2003

Sorry for asking a dumb question. 1992- 150hp Evinrude, engines are new to me. I want to change the lower unit fluid and cannot get the plugs out. Tried a hand held impact tool, broke the screwdriver bit. Put some PB Blaster, no help. bought the bigest screwdriver they had at home depot and put an adjustible wrench on the shaft, no help. Are these standard thread screws? Righty tighty, Lefty loosey??? Any suggestions would be great. thanks, Mike

crazy charlie · Sep 16, 2003

Re: Lower Unit Drain Plug

I would try the big screwdriver and give it a good shot with a hammer first.The only thing that can hold the screw in like that is galvanic corrosion.You may want to try heat but be careful,dont over do it,there are seals in there.If you can get the top screw out see if there is water in there.Good luck Charlie

crazy charlie · Sep 16, 2003

Re: Lower Unit Drain Plug

Yes they do turn in the usual direction.

Joe Reeves · Sep 16, 2003

Re: Lower Unit Drain Plug

Michaell.... Strange that a hand held impact screwdriver wouldn't remove those screws. They screw out counter clockwise, tighten clockwise. If you're still having a problem, use a hand held propane torch to heat the area around the screw which should expand the surrounding aluminum somewhat, then try the handheld impact screwdriver again with a hefty tip.

ob · Sep 16, 2003

Re: Lower Unit Drain Plug

I'd try it with a good case hardened tip before applying the heat first.A good impact tip of the proper size would not have broken very easily.Sure hate to hear when people overheat things and cause further problems.

OBJ · Sep 16, 2003

Re: Lower Unit Drain Plug

Mike.....sometimes a flat tip punch will losen the screw with a wack or two in the loosey direction. The plug screws are replaceable if the slot gets dinged up.

Mike Langianese · Sep 16, 2003

Re: Lower Unit Drain Plug

Thanks for the input, I did use a case hardened Impact screwdrive bit in the hand impact tool, shattered in a million pieces. I couldn't locate a replacement bit on the shelf, had to buy an new tool. My old crasftman is over 30 years old, new tool not up to the quality. When that bit twisted and started to bugger up the slot I thought it best to stop and seek sage advice. Will order a new bit, I'll buy some replacement plug screws and try the punch idea. Will keep you posted, Mike

rodbolt · Sep 16, 2003

Re: Lower Unit Drain Plug

Hello Try the 5/16ths driver bits from Napa. they seem to hold up for a while before shattering. and when you put it back together use the omc plugs with the white gaskets. OMC quit using the oring plugs and the plugs with gaskets come out easier

. good luck and keep us posted If you strip it I can explain how to modify a 3/8 x 16 heli-coil

Mike Langianese · Sep 17, 2003

Re: Lower Unit Drain Plug

Rodbolt, I went to a smaller NAPA store they didn't have the screwbit and said it wasn't in the book so couldn't order it either. I will try a larger store. I'll be sure to ask the parts guy for the plugs with the gasket, thanks for that tip. NAPA carries alot of parts for tractors etc. do they also carry outboard parts? I'll see what I can find today and let you know. Mike

Mike Langianese · Sep 17, 2003

Re: Lower Unit Drain Plug

Update but no progress, Located several of the impact bits for the hand driver, almost twisted on 90 degrees, no effect on the drain plug. Neither NAPA nor the local Evinrude dealer had the plug in stock, they could order. I noticed some corrosion around the screw head, although it may be the remnants of barnacles. Im searched the archives for a chemical to remove it and only found a recommendation to use a lime away product used on cookware. I have a pressure washer shall I pressure wash the lower unit? Mike

crazy charlie · Sep 17, 2003

Re: Lower Unit Drain Plug

I would try the bottom cleaner called "on-off".you have to be careful not to leave it on too long because it is an acid and I dont think it is recommended for metal.I have used it many times on metal you just have to rinse it thoroughly and as i stated,dont leave it on too long. Charlie

Mike Langianese · Sep 19, 2003

Re: Lower Unit Drain Plug

Hello All, I guess by this time you must be tired of hearing of this but I wanted to detail what I have tried so far without success,

Hand Impact Driver,
PB Blaster,
Large screwdriver with assistance from crescent wrench on shaft
Lime Away, removed lime and crud from the plug area and on some exposed threads,
Tapping on leading edge of plug with small punch,
Small amount of heat from propane torch
Follow upped by use of impact driver and screwdriver

While adding heat I noticed what I think is black paint in the threads, I suspect that a previous owner repainted the foot and got paint on the threads. I am going to put some paint remover on the plug to soften any gunk and try again. I did not use a large amount of heat, How much heat is too much? Or is it that you find out when you fry some seals? Shall I continue in my attempts to remove the plugs and replace the fluid or should I put it off until winter and work on it then and/or pay someone to do it? What about using an air driven impact tool? Any other ideas?

Mike

Joe Reeves · Sep 19, 2003

Re: Lower Unit Drain Plug

I've been following this thread and am amazed of the problem encountered in removing a drain screw. In my many years of experience, this is one problem I have never encountered. That hand held impact screwdriver..... are you turning the handle of that tool to its full counter clockwise setting so that when you hit it, it turns the screwdriver bit counter colockwise? Heat.... How much is too much? You can't overheat that unit with a hand held propane torch. You'll simply need to replace the drain screw seals is all.

Hooty · Sep 19, 2003

Re: Lower Unit Drain Plug

I'm a big believer in air impact tools so I'd say yeah, give that a try. Be sure the screwdriver bit fits good and snug in the slot. c/6 Hooty

The Marine Doctor · Sep 19, 2003

Re: Lower Unit Drain Plug

I have used the impact screw driver...as well as a punch in the corner of the screw...both successful. TMD

ob · Sep 19, 2003

Re: Lower Unit Drain Plug

The reason that I lean on the side of caution in this case against the use of heat is that when used in conjunction with a hammer type impact driver which has to be pounded inward in order to develop its torque ,it could potentially cause deformation of the sealing surface and surrounding housing which supports the carrier and threaded screw once enough heat is appied to expand aluminum housing .Perhaps heating enough to melt the nylon seals and then letting cool before attempting to use hammer driver would be safer.As Hooty mentions insure that the driver blade is a no slop fit in the slot of the screw.Sounds like you have a bugger on your hands.

Mike Langianese · Sep 20, 2003

Re: Lower Unit Drain Plug

Thanks for the info especially that I cannot damage anything other than the plug seal itself by adding heat (allowing that I don't damage the threads). I even thought I had the hand impact driver set wrong so I tested it on a wood screw.

I had it set correctly. This has everyone including me, scratching their heads wondering what's the problem. I will order some new plugs and try an air impact gun than put the heat to it. I am wondering when it's all said and done will it will come to drilling a hole into the plug and using an easyout! Thanks again Mike

Steve adams · Sep 20, 2003

Re: Lower Unit Drain Plug

Mike, I am no expert, but I have had stuck screws before, when using the heat, remember the opposite is cold, if you can cool the bolt quickly it might break the corrosion on its own. I have put wrenches in the freezer overnight and used this with some success. Maybe cold screwdrivers or if you can freeze some water in a piece of hose, and cool the scew with it. Try to cool just the screw. Good luck!!!

Mike Langianese · Sep 25, 2003

Re: Lower Unit Drain Plug

Hello All, No progress on removing the drain plugs.

I had to order new plugs, picked them up today. Applied heat and then used a VERY large screw driver with a wrench for leverage...Twisted the screwdriver tip into a corkscrew. Have not been able to locate proper size bit for impact tool so did not use yet. >>>Shall I drill a hole into the plug and attempt to use an "easy-out" to remove the plug? >>>TIG Weld a tab onto the plug and put a wrench on it? Will the high frequency from the TIG welder fry the charging system??? was about to give up and pay $90 an hour but the shop says they would do exactly what I have tried...suggestions??? I am wondering if the plugs have been JB Welded inot place.

thanks all Mike

pbailey · Sep 25, 2003

Re: Lower Unit Drain Plug

I don't think an easy out will give you any more leverage on it than you have already applied. In fact you will probably end up with an easy out broken off in the hole you drill and then where would you be. Like a tap, easy outs are case hardened and are brittle. If it comes down to it you can drill all they way through the screw as close to the center as possible. then use increasing sizes of bits until you have very little material left between the screw and threads. Then use a punch and other probing type tools to collapse the remaining part of the screw in on itself until you can remove it. I have done this when all else fails. But you only have one shot at it, so you have to be very careful not damage the threads. In some cases while doing this the heat generated while drilling and the relief of the hole drilled as the bit nears the threads as caused the screw to break loose and spin with the drill bit. pbailey

Lower Unit Drain Plug

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