Lower Unit Drain Plug

[ob]

Re: Lower Unit Drain Plug

This is most amazing.I'm having a difficult time visualizing this ordeal.After having attempted to remove by using a punch on the edge of the slot you can still get enough bite with a large screwdriver and a wrench and torque to the point of twisting the blade?What kind of screwdriver are you using?Wal Mart special.I've got sets of Stanleys and Snap-ons that would not have cratered so easy.If in fact it is as tight as you have described ,I strongly doubt that an easy-out will fair better.Won't hurt drilling out and attempting at this point.You're a lot more patient than I am ,that's for sure.

 

[Hooty]

Re: Lower Unit Drain Plug

If you have access, go ahead and TIG weld a hexhead bolt onto it. Just keep the ground close to the plug when you do it and the electronics should be ok.<br />Of course, when you do it you're committed. There'll be no more trying to use a slotted screwdriver, or anything else for that matter.<br /><br />g'luck & c/6<br />Hooty

 

[Mike Langianese]

Re: Lower Unit Drain Plug

Hooty,<br /><br />After all the work on the slotted screw the slot is getting buggered up a bit, I can still get some purchase with a properly sized bit but not for long. <br /><br />That is why I think the only thing left is to drill the plug out or to weld something onto it.<br /><br />>>>Any precautions I should take if I go the TIG welder route?<br /><br />>>>This type of plug has the small magnet on the interior, I am concerned that if I attempt to drill--- the magnet will become unattached and float until attaches to a gear or something.<br /><br />>>>I will try the flat punch again before drilling or welding.<br /><br />OB-- The impact driver bits were Craftsman; three broken bits, I was in a hurry and rushed out to buy the largest screwdriver I could find, <br />not wal-mart special but the "unbreakable" that The Home Depot sells, should have tracked down a Snap-On truck.(and will). Quality of the screwdriver looked good but the steel must be trash. My fault on that point.<br /><br />Have lost what little patience I had but wanted to have replacement plug in hand to see what I am dealing with. <br /><br />Replaced the Zincs, one completely gone the other crumbled to 1/4 size when handled. A lot of Salt Water! The bolts holding the zincs in came out with out any force whatsoever!<br /><br />Thanks for your input<br /><br />Mike

 

[ED21]

Re: Lower Unit Drain Plug

Sounds like a real tough nut to crack. I'll mention this because nobody else seemed to. Spray Liquid Wrench on the plug at least daily for a week or so. Tap the plug also after spraying.<br />I've had this work on stuck bolts & plugs before.<br /> Someone else mentioned cold after heat. They sell an aerosol for testing electrical components. Maybe that would help break the seal.

 

[Mike Langianese]

Re: Lower Unit Drain Plug

PBailey and OB<br /><br />I agree that the easy-out may break in the plug and cause an entirely different set of problems.<br /><br />As for the liquid wrench, I have been using PB Blaster because of what some posters have had to say about this product. I guess liquid wrench couldn't hurt.<br /><br />Ed,<br /><br />As for your and Duckeys suggestion to use cold, I'll try to make a clay dam around the plug to protect the housing from the cold and try the aerosol spray to cool the part.<br /><br />This is really amassing how hard this plug is in this unit. <br /><br />Mike

 

[ob]

Re: Lower Unit Drain Plug

Michael,If you drill the plugs make sure and use a center punch before drilling and get the holes drilled as exact to center as possible.This way whether you choose to use an easy out or progressive drill the plugs until the thread wall,in many cases can be peeled out after the edge is caved in with a suitable punch.Use some good cobalt drill bits starting with a small pilot hole and working up..It will make the job easier.Good luck in your efforts.

 

[ISkiH2O]

Re: Lower Unit Drain Plug

Try muratic acid. Have plenty of water to wash everything down, don't get any on your clothes or skin.

 

[Hooty]

Re: Lower Unit Drain Plug

Another good source of "cold" is either liquid Freon or propane. It goes without saying, that if you use propane be extreamly careful. I'd be a little reluctant to freeze the thang because of the different expansion rates of the stainless and aluminum. Taking it down to -40* might cause the aluminum to crack arount the plug.<br /><br />c/6<br />Hooty

 

[93bronco]

Re: Lower Unit Drain Plug

if you are going to drill, make sure to use reverse drill bits.<br />mite help to free when drilling out.

 

[cpasseno03]

Re: Lower Unit Drain Plug

Heres my recipe for stuck screws, never failed me once. Use the hand held impact driver with a bit that fits snugly, its seems as tho you have not encountered this problem yet, but I think it has a good chance of occuring, (stripping the head) a good way to avoid this, or to combat it, is to put a bit of valve grinding compound on the tip of the screwdriver, or other abrasive goop... it adds traction. heat shouldnt be necessary with such a small screw. 5/16-18 I think... Your impact driver should be able to break it off with a good twist and an even better smack. But the screw should definatly come out before it broke...I just cant imagine a screw of such manner causing such a problem.<br />Craig

 

[rodbolt]

Re: Lower Unit Drain Plug

Hello<br /> all I can say is wow<br /> I have never heard of a drain screw that tight. if it were mine the oxy/acetylene would have it loosened already. the aluminium casting will take a lot more heat than you think. if you try to drill it the thread size is 3/8-16 the tap drill size is 5/16ths. make sure you drill straight and true otherwise the drill size for a 3/8-16 heli coil is 25/64ths. the hard part is to cut a standard helicoil in half without damaging it. I would try taking it some where that the tech was used to saltwater engines and is proficient with a torch.remember you are trying to heat a very large heat sink. If you have to heli coil it wipe omc gel seal on the OD of the coil and then you MUST use the drain/fill plugs with the white nylon gasket.<br />If your not comfortable with that then send the unit out.<br /> I have removed many broken studs and easy outs with a welder . if you weld on the plug dont try to drill it. if I was going to drill it I would use a carbide bit only. some times stainless and cobalt wont get along and you can work haarden the stainless so hard a drill wont touch it.<br /> good luck and feel free to email me at rodbolt40@yahoo.com.

 

[Mike Langianese]

Re: Lower Unit Drain Plug

HALLELUIAH!!!<br /><br />After Heat, Cold, PB Blaster, Liquid Wrench, Lime-Away, Use of a Chisel, 3-broken hand impact driver bits (Craftsman) and a twisted “unbreakable” screwdriver and with the suggestions from many here; I have finally succeeded in changing the lower unit fluid on both engines. <br /><br />Xcusme mailed me an impact bit that he uses for the task. It did the job. Kudos to Xcusme and RodBolt for their assistance.<br /><br />The plugs were fitted with “O” rings and were tightened so tight that the “O” ring was almost non-existent. Corrosion formed between the underside of the plug head and the lower unit.<br /><br />Ordered replacement plugs from a local dealer, 3 plugs are standard slotted screws (slots are narrower than the old plugs and the large impact bit will not fit the new plugs without grinding!) the 4th plug is not a slotted head screw it has a recess allen-head that looks more suited for assembling knock down furniture.<br /><br />Thanks again for your assistance and advice.<br />I'm sure to have more dumb questions

 

[JMatt1022]

Re: Lower Unit Drain Plug

I am having the same problem on my 1988 85HP Force. My boat is a twin-screw. The lower unit drain plug on the first motor came out no problem, but the second motor has destroyed 3 allen wrenches. Where can I find the impact bit you used?

 

[James R]

Re: Lower Unit Drain Plug

Always had success with the Sears impact driver and a 24 OZ hammer.
A good smack is required sometimes two.
If you use inferior tools you get inferior results.

 

[iwombat]

Re: Lower Unit Drain Plug

Easy out isn't even an option in my opinion. If you're going to drill, use left-handed bits. Chances are, the screw will come out by itself on the drill bit.

 

[bman1bpm]

Re: Lower Unit Drain Plug

I've got the same problem with my drain plug...except the previous owner stripped the head of the drain plug. I broke the tips on some impact driver bits. Going to go the drill out route on mine, I"ll let you know how it goes.

 

[Bsquared]

Re: Lower Unit Drain Plug

I had the same issue on a saltwater '77 that had been sitting for several years. Chewed up the slot with no luck and had to drill. Broke off the first easy-out, which fell inside the gear case :-( Managed to drill out almost the whole screw diameter and then the threads finally came out with an easy out. Fished out the broken easy-out tip with a magnet and coat hanger wire There was definitely some corrosion on the threads, and not just under the head; I wouldn't bet on solvent getting past the gasket. Getting the drill bit centered to start with was CRITICAL. My local NAPA had drain plugs in stock (but it's in a waterfront community).

 

[bman1bpm]

Re: Lower Unit Drain Plug

I'm hoping the local marina that has old stock and used chrysler parts will have some drain plugs. Need to pick up some reverse drill bits too.