I just cross threaded the oil drain plug on my F150 4 stroke Yamaha. NOW WHAT DO I DO? I can’t get the plug to tighten up now. Does anyone have an idea what the solution will be. I intend to get professional help on this but would like to have an idea what the best solution for the long run will be to avoid trouble in the future. I’ll apreciate hearing if anyone has had a similar experience and what was done.
You have 2 options.
Put a helicoil in like you would for a spark plug. If done right it will last a while.
Replace the mid section of the motor which also requires the power head to be pulled.
We had a customer do the exact same thing and he ended up going the route of replacing the mid section.
Wow,…what a bummer. I’m sorry that happened to you. I hate changing oil. I botched a filter replacement once. Good thing I needed gas and found the trail of oil back in my garage before I lost enough to damage anything. I am paranoid now. Four strokes aren’t always better than a 2 stroke!
before you try a heli-coil,( which is a great option if there is room for it)
go to a local parts store and look through their oversize drain plug assortment and see if you can find one that is just a little bigger than your original one.
if you find one that will work,see if they have a tap that size also,if they do,fill the fluting in the tap with grease,(this will trap most if not all debris).
if they dont have a proper tap,an oversize plug will cut its it own threads,just take your time at it,ie,a half turn or so in,and then back it out like you were using it for a tap.
I have done this on many magnesium and aluminum oil pans on vehicles and small engines and never had a problem with them leaking.
good luck!!!!!!!!!!!
I’d give the helicoil’s a shot and use some teflon tape when putting the drain screw back in. I’d bet that works for quite a while.
before you try a heli-coil,( which is a great option if there is room for it)
go to a local parts store and look through their oversize drain plug assortment and see if you can find one that is just a little bigger than your original one.if you find one that will work,see if they have a tap that size also,if they do,fill the fluting in the tap with grease,(this will trap most if not all debris).
if they dont have a proper tap,an oversize plug will cut its it own threads,just take your time at it,ie,a half turn or so in,and then back it out like you were using it for a tap.I have done this on many magnesium and aluminum oil pans on vehicles and small engines and never had a problem with them leaking.
good luck!!!!!!!!!!!
+1
Run to napa they have many different oversize plugs n taps
I’d give the helicoil’s a shot and use some teflon tape when putting the drain screw back in. I’d bet that works for quite a while.
Unless they are tapered the threads on a drain screw do nothing to seal the plug, the o ring is the sealing surface. No need for Teflon tape, if anything it adds the potential for a contaminant to get into the oil. Also helicoils are just a precision ground spring shaped into threads, they will never be a sealing surface as oil will run right between the coils.
The biggest thing to look for if you want to go with a helicoil is to be sure the sealing surface on the plug is larger than the outside diameter of the helicoil. Thread the helicoil onto the plug, if you can see most of the o ring there is a very good chance it will seal, as long as it was drilled and threaded perpendicular to the surface. And if it doesn’t fully seal it you can always place a bead of RTV silicone on the sealing surface of the plug and reinstall it, just be sure to let it cure before using the motor.
Lots of conflicting info ! If the plug still fits I would use a sealant and snug it up. If the plug is loose use some tape and sealant around the O ring.
I don’t understand how the plug gets cross-threaded. It is not tapered and you can screw it in almost all the way with just your fingers on the socket or extension.
If the treads in the aluminum have been stretched so it doesn’t go in easy it may have been over tightened. Always use a torque wrench!
I would first look for a over sized plug and tap to that size.
Also, my owners manual for my Yamaha F150 recommends not using the drain plug and instead using a oil draining pump that sucks the oil out from the dip stick hole.
That is what I use and it works great.
What year is your motor? My manual does not say anything about a pump.
I don’t understand how the plug gets cross-threaded. It is not tapered and you can screw it in almost all the way with just your fingers on the socket or extension.
If the treads in the aluminum have been stretched so it doesn’t go in easy it may have been over tightened. Always use a torque wrench!
I agree with using a torque wrench especially when working with aluminum and magnesium.
depending on the thread pitch on a metric bolt or plug,especially the finer pitched ones when used in aluminum,they can be very easy to cross thread,I know,I have done it even though I was sure it started by hand a turn or two,and yes,I had to fix it,dang!!
I would follow Iowaboy’s advice. Also, I personally know a guy who really did have the most expensive oil change ever. Filter spun off while driving and cost him a new engine. 
I would first look for a over sized plug and tap to that size.
Also, my owners manual for my Yamaha F150 recommends not using the drain plug and instead using a oil draining pump that sucks the oil out from the dip stick hole.
That is what I use and it works great.
I began sucking the oil out of all my engines after using it on my I/O. Panther make a good vac pump for around $60 if I recall.
The dipstick (where you insert the vac tube) actually runs deeper in the pan than most drain plugs meaning you get more oil out than by pulling the plug.
Tap out one size bigger with grease on tap, reinstall new bolt and gasket then run for 20min and do a full oil change with filter. At least that would be my plan of action. You may feel uneasy doing it all but it should give the desired result.
Most auto mechanics do this repair a lot thanks to the quickie oil change places. Call a couple independent mechanics and tell them what you need, it will be about $30. What I prefer to do is red loctite and helicoil. Use a torque wrench in the future. Don’t stress about it, common mistake and easily repaired.
Also, my owners manual for my Yamaha F150 recommends not using the drain plug and instead using a oil draining pump that sucks the oil out from the dip stick hole.
My 225 offshore doesn’t have an easily accessible drain plug, so I use an extractor pump. Already had one to change oil on the wife’s mini cooper. Works like a charm.
before you try a heli-coil,( which is a great option if there is room for it)
go to a local parts store and look through their oversize drain plug assortment and see if you can find one that is just a little bigger than your original one.if you find one that will work,see if they have a tap that size also,if they do,fill the fluting in the tap with grease,(this will trap most if not all debris).
if they dont have a proper tap,an oversize plug will cut its it own threads,just take your time at it,ie,a half turn or so in,and then back it out like you were using it for a tap.I have done this on many magnesium and aluminum oil pans on vehicles and small engines and never had a problem with them leaking.
good luck!!!!!!!!!!!
This ^^^. Either do it yourself or have a mechanic do it for you.
+1 on this being a common repair. And one of the best reasons for owning a set of torque wrenches if you don’t already.
Grouse
My concern would be, If you use a self tapping plug or helicoil, there are metal filings that could get into the crankcase. These filings could get picked up by the oil pump and circulated through the lubrication system. A friend of mine just had a new 150HP yamaha power head replaced, $6000, and that did not include labor.
I don’t understand how the plug gets cross-threaded. It is not tapered and you can screw it in almost all the way with just your fingers on the socket or extension.
If the treads in the aluminum have been stretched so it doesn’t go in easy it may have been over tightened. Always use a torque wrench!
I change mine all the time and never use a torque wrench. Finger tight, then 1/4 inch drive rachet to snug it up. Just has to be tight.
His power head failed because he used helicoil to repair his drain plug threads? Sounds fishy to me. Was he also not running an oil filter or how does the debris get into the system? If there was debris from not knowing how to install helicoil why wasn’t it removed then. I just don’t understand how that equates to a power head replacement.
Go to your local auto parts store and explain the problem. Might take going to a store or 2 or 3 to get that right guy to help you. Might not be a dumb idea to bring the boat with so they can see how loose the bolt is in the threads and what the best option is. If the threads aren’t totally crapped out, it could even be re-tapped to the same size as the original but I doubt it. Next best thing is up-sizing the drain plug bolt. If that’s not an option, tap it to the next size up and make sure that bolt size, length and collar size work on the surface of where the drain plug bolt sits. And do the tape process slow and easy, with backing it in and out as it cuts the new threads in. I’d only do a helicoil as a last resort. If that’s the only way, I’d go with a new compression copper type washer, a good nylon one or whatever works to seal where the bolt and threads meet, so you can get a good leak proof seal. Then I’d put a new one on every time it was unscrewed for any reason. I wouldn’t put anything like teflon tape or a pipe dope on a bolt that threads into any of my oil pans on anything other than as a last resort, to much risk of getting a contaminate in the life blood of that motor. Good luck with it and you aren’t the first or last guy to do it, so don’t be to hard on yourself, it’s fixable and it happens.
What year is your motor? My manual does not say anything about a pump.
2013. Page 74 in the owners manual. The owners manual doesn’t even say where the drain plug is.
Thank you very much for all the replys. I think I have the problem solved. I checked the tapped opening and found that the openning is threaded aprox. twice or more than used by the OEM plug. I ordered a plug from O’Reilly Auto parts that had a threaded length about twice the length of the original. With patience I finally got the threads to engage past the stripped threads by hand up to the gasket and finished by torqueing to mfg. recommended specs. Before I got the ordered plug I tried one off the shelf that had a nipple to guide the plug in. This probably helped get entry to the good threads past the stripped ones. That plug would not snug down on the seat because its flange was too big and contacted the housing before seating. It was also necessary to cut off the rubber nipple to see what I was doing. Although I believe I could continue to use the drain I’m not going to risk further problems and will vacuum or pump the oil out from now on.
Good job!! bet the pucker factor went down by about eleven points!!
thanks for posting the great result!!
Sounds like you are back in business. I bet you sleep better now. 
You guys got that right. I was crying in my beer, not sleeping good and saying a few prayers that something would work along with kicking myself for being so dumb. I had changed the oil numerous times without problem but got fooled by the short plug, the angle it goes in and the rubber drain assist that hides the plug and hole. Word to the wise, if you remove that plug make sure it is threaded most of the way in by hand before you ever get a wrench near it but better yet don’t touch it and pump the oil out the dip stick hole as recommended in the manual.
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