remove broken off screw

[HarleyC]

This screw was broken off in the aluminum head. I there a good penetrating oil for freeing up "frozen" screws in aluminum. I already tried rust buster, and WD40. The screw is stainless steel 1/4-20 thread. It appears to be oxidzed/ corroded as well. I then drilled out the screw to it take the easy out, but it wont budge. Its a small easy out. Also used a little heat from the propane torch, but worry about over heating the aluminum. Just hoping they did not bottom out the screw when it snapped. Any thought appreciated. Fishboy

 

[93bronco]

Re: remove broken off screw

if it wont budge quit with the easy outs!! they are brittle and will break very easy. if you drilled all the way through stud <now> you mite be able to lube from inside out to help. some one else with more knowledge should read your post. have you tried -search- under broken bolts? there was a thread not to long ago on that with an exaust housing bolts. take your time and dont rush it.

 

[plywoody]

Re: remove broken off screw

A number of years ago there was a shop in Port Angleles, Wa that had a machinist that had this nifty way of getting steel screws out of aluminum blocks with a circular electrode that would burn the screw out without any damage to the threads or aluminum block. <br />I have no idea what this process was called, or whether there are anyone that has the technology near you, but it was sure good to have him around when I used to work on my old Merc outboard. With my Johnnyrudes, I have had no further trouble in this regard. Perhaps someone on this board knows the technical name for this proceedure, and how to find out who has it...<br /><br />I am pretty impressed that you could drill a stainless steel screw in an Aluminum block without messing up the aluminum, however

 

[OBJ]

Re: remove broken off screw

fishboy....what kind of engine are you working on and where is the screw located. If it is an original screw, it probably will not be bottomed out. If you have not drilled all the way through the bolt yet, do so being careful not to go any farther. Once through, shoot some blaster in the hole and let it soak again. Or, if the hole you drilled is dead on, increase drill size a little at a time until you can get get a 1/4/20 tap started and rethread the hole. Use WD-40 as a lube while threading and drilling.

 

[93bronco]

Re: remove broken off screw

i forgot to suggest a reverse drill bit, sometimes it will twist the stud out.

 

[jim dozier]

Re: remove broken off screw

Good suggestions,<br />I had a similar situation. I echo the advice to avoid the easy out from personal bad experience. I had a thermostat cover bolt break off even with the head. Then I broke off the easy out in the broken stud. I had to get a carbide tipped tile cutter for my dremel to chew up the easy out. Using extreme care and attention to centering and alignment I was able to drill the bolt out using small incremental increases in drill size. That sucker never did let loose. I had to retap it for a helicoil insert and the problem was solved. If you can drill all the way through and get some PB Blaster oil behind it and let it soak overnite you might get lucky with the largest size easy out that will fit the stud (don't use a small one). But don't use much torque on the easy out because they can and will break and are a bear to remove. By the way, with a new set of drill bits, I have had no problem drilling stainless steel studs, make sure to start with a center punch.

 

[Walker]

Re: remove broken off screw

If you are talking about a small propane torch with a disposable bottle then go for it. You won't melt the aluminum with it. Don't use Mapp gas though.

 

[OBJ]

Re: remove broken off screw

Guys...I don't think the bolts are true stainless or you would never get them drilled. I believe they are an alloy type stainless, just a little softer than real stainles but more resistant to corrosion. Put a magnet next to a "stainless" prop and see what happens. Also, ditto on jimd's comment about keeping the drill centered. Once you get off, getting it straight again is nearly impossible.

 

[Bobby D.]

Re: remove broken off screw

Hello Board, I would like to end the mydth that "stainless steels do not attract a magnet". Wrong. Like all metals they are designated by a metallurgical number (if you will) stainless steel usually have a three number designation. The 400 series are usually magnetic. What that means is, is that it has a higher carbon content. A trained eye can sometimes tell stainless by its color. Another method is to take a piece of known stainless and the piece that you believe is stainless and do a spark test on a grinder. Metalurgy 101. I like the left handed drill idea but when working with any steel be careful not too break anything harder than what you are trying to remove. Good luck . Ake if you need more help.

 

[ob]

Re: remove broken off screw

fishboy,If you're still there,I tend to lean more toward the heat method of removing a bolt of that small size that is froze.Rather than running your heat in an attempt to expand surrounding metal ,try concentrating the heat to the bolt shank itself until almost cherry red.Let cool completely.Then attempt removal via easy-out.This method is quite effective at expanding bolt and breaking scale bond,however you must let it cool completely after heating.

 

[plywoody]

Re: remove broken off screw

I am kind of surprised that the pros on this list do not seem to be familiar with the electrical removal of broken bolts and such.<br />All of the local shops used this guy, as I did. It was the slickest removal technique I have ever seen--after initial setup, it would take only a matter of seconds, and it would automatically stop when the bottom of the bolt was reached, as it would lose contact and stop on its own. It would take out the entire screw, exept the remnants of the threads remaining, which easily could be brushed out.<br />And none of the hassels with heating and drilling or any of the rest...<br />That was back in the mid-80's and he charged something like $10 per broken bolt, and he had a set of different sized electrodes to take out any size bolt-it didn't matter.<br />Just curious...<br /><br />John

 

[HarleyC]

Re: remove broken off screw

Hey Guys thanks a ton, First, it's the thermostat cover screw on an '86 Force 125 hp. It drilled real easy, so I agree it may not be a regular class Stainless screw. The broken part is about 3/4" long and there is no stub. OB,Walker, I aimed the propane torch on the screw its self and tried to avoid the AL as much as possible. Dude, Good avice, Jimd, I drilled all the way thru, trying to get heat all the way down in there. The threads go all the way through to the galley ways. Thought they would be blind holes. OBJim, I drilled a little off center (a little ugly) now the hole is very near the threads. I used the correct easy out thats in the set I have, so drilling oversize is not an option, yet. 2K boat, I'll try to find that thread, no pun intended. Plywoody, the machine you saw was likely an electric discharge machine. Elox makes a number of small portable models that are handy for removing taps and bolts too. It cuts with a carbon electrode in an electrolyte bath. If every thing else fails I may have to pull the head and take it in. I did not get a chance to try again today, was busy installing a Trolling motor on my sons boat. I will let you all know how this comes out. Fish

 

[OBJ]

Re: remove broken off screw

Hey Fish....nuts to that.....let the boy get the stud out and YOU use the trolling motor on his boat. (sounds fair to me) LOL!

 

[Boatist]

Re: remove broken off screw

Fishboy<br />I had a broken Stainless bolt on the outdrive. I drilled a hole and tried a easy out but no luck. Could see Salt around outside of bolt. Tried to disolve with water but no luck. Tried every oil I could find but nothing helped. Tried heat but no luck. So I drilled a bigger hole until could start a tap. Slowely worked tap to the bottom but when I tried to remove I broke the tap. Tried to drill it but nothing would even start to cut.<br /><br />Finally used a drumel tool with a diamond bit and ground it out bit by bit. Took most of two days, and I figured would have to then drill bigger and tap to next size, but got two new taps and to my suprise tape out fine to same size. This time I had a bottom tap so could tap to bottom of thread. Before was useing a standard tap and problem I had is would not tap deep enough for bolt to go all the way in.<br /><br />The key is get the right tool and take it slow and easy. I learned my lesson the hard way.<br />Best of Luck

 

[roscoe]

Re: remove broken off screw

I talked with the guys in the shop today and 1 had a possible solution.<br /><br />First drill for easy out.<br />Second, using a 10 amp battery charger, hook pos lead to bolt, insert a similar metal stud into easyout hole if needed.<br />Third, hook neg lead to aluminum.<br />Let it run for 4 or 5 hours.<br />He claims the electrolisis that will take place between the alum and stainless will be enough to weaken and breakdown the stainless threads. <br />Disconnect and us easyout to remove stud.<br /><br />As always, do this in a safe manner. And remove all the electronics from the engine before you connect the charger.<br /><br />Don't shoot me, I'm only the messenger.

 

[spete]

Re: remove broken off screw

Hey OB/Corpus - waded the ole shamrock cove a few times - beautiful out there ...<br /><br />Q: I've got a CMC jackplate which uses a tiny bronze hexhead screw in the fill hole. Of course I stripped it out while attempting to check/add fluid. Will your method of heating/focusing torch on the bronze screw that's stripped out inside an aluminum hydrolic box filled with fluid work? is there a risk of the fluid igniting inside the box? I also want to remove the vent plug on the side of the alum. box - any recommendations on how to get that one out without stripping? Thanks for your thoughts!

 

[ob]

Re: remove broken off screw

spete,Are these allen drive pipe plugs or hex head gasketed screws?If allen head The right size easyout may be the ticket.Shouldn't be much corrosion beyond initial threads on oil reservoir plugs.Threads will be tapered.Post back with type of plug head and size if known.

 

[spete]

Re: remove broken off screw

the plug is a 3/16 allen head - I've got a set of screw out-like tools (look like a reverse drill bit) is this the same as an Easy-out. Easy-Out a brand name tool? I used the larger one on a bigger bolt a while back and it was very brittle and snapped off.

 

[ob]

Re: remove broken off screw

Spete , without drilling if there is enough depth to allen hole,or whats left of allen flats,a larger square easyout hammer wedged in hole may work.I would advise against heat on oil reservoir,for fear of transfering to internals and pressure buildup.May have to drll through and use good round type easyout to extract.However ,this can leave drill filings in reservoir and a flush afterwards would be in order.<br /><br />Shamrock Cove is one of my favorite honey holes to hammer the reds in the spring.

 

[spete]

Re: remove broken off screw

thanks OB - where can i find an "easyout" hammer or the round version? Not familiar with that brand. Also, I respect your opinion and wonder if you would take a look at the post I put up on the 115 yamaha today. Thanks for your thoughts.<br /><br />* before I owed a boat i used to walk in/wade to shamrock from the island. Lots of great guts and bottom structure as you walk around out there. I've been splitting my time between Port O and Port Aransas these days ... I've had some pretty good days over in east flats but never ventured much into shamrock since i've gotten the boat.