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PLEASE HELP! Best way to remove broken 1/4" bolt studs from aluminum engine block?

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PLEASE HELP! Best way to remove broken 1/4" bolt studs from aluminum engine block?

Old 06-26-2015, 02:45 PM
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Question PLEASE HELP! Best way to remove broken 1/4" bolt studs from aluminum engine block?

I have an Evinrude 88 spl. I removed the exhaust cover plate to replace the leaking gaskets. In doing so, I broke 10 bolt heads off leaving just the 1/4" stud. I got 5 of them out with vise grips and wd-40. The other 5 won't budge. The vise grips just round off the stud. Any ideas? I saw some people on YouTube weld nuts to the stud and back it off that way. People I have talked to say the bolt extractor tool won't work in this situation. Maybe drill the bolt out and tap to a bigger thread size? I called 6 auto machine shops in the Houston, Tx area and none of them will touch it (motor/power head still on boat, just didn't want to hassle with it). I had one guy hang up on me after I explained my story. I'm stuck and any ideas would be greatly appreciated. Thank you
Old 06-26-2015, 02:51 PM
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Welding a nut on is pretty much your only shot. Let PB blast soak on them overnight before you put a wrench on them.

Can't "drill them out" because they're stainless while the alloy around them is soft.

Have done the above also with PB blast soak, heating, soaking again, heating- over days. It eventually will come as long as you don't lose patience and break the bolt again where there's not enough left to weld to.

Degrease and grind a little before you weld.


If you finally get the stud out by turning and stripping the block's threads, then you can overdrill and use heli-coils or similar product. This happens in automotive transmission pan screws and screw holes in the casing pretty often as they're made of softer metal.
Old 06-26-2015, 02:58 PM
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These actually work pretty well but just be careful to hold the rod centered.

http://www.inweldcorporation.com/hi-...0extractor.pdf
Old 06-26-2015, 02:58 PM
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Are you saying you have 1/4 in of stud exposed or 1/4 in diameter studs?
Old 06-26-2015, 03:06 PM
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If you can get vise grips on them you should be able to get a small pipe wrench on them.

I've tackled some tough bolts over the yrs and every time I was able to get a pipe wrench on them I was able to get them out.
Old 06-26-2015, 03:09 PM
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Sorry, I don't remember the name of the tool but it extracts broken studs well. It works with a break over bar. It looks like a round knurled disc which pivots on a pin over a hole. The hole is placed over the stud and when the wrench is turned the knurled disc locks onto the stud.

For your job the cost of the tool would be worth it, IMO.

I recommend use of PB Blaster and a propane torch with the "stud remover". You don't want to break those studs off flush with the aluminum block.
Old 06-26-2015, 03:12 PM
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I'd not F around too much lest the situation be made worse. PB blaster overnight & gentle heat, repeated a few times... it is the heat cycling that does most of the work.

Then weld a nut on, let it cool completely before turning. In this case, I'd actually try tightening a wee bit if the first attempt at loosening didn't break it free.

Worse situation is you break off lower than the surface of the head... SS bolt, soft threads as said.
Old 06-26-2015, 03:13 PM
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Originally Posted by Butch Davis View Post
Sorry, I don't remember the name of the tool but it extracts broken studs well. It works with a break over bar. It looks like a round knurled disc which pivots on a pin over a hole. The hole is placed over the stud and when the wrench is turned the knurled disc locks onto the stud.

For your job the cost of the tool would be worth it, IMO.

I recommend use of PB Blaster and a propane torch with the "stud remover". You don't want to break those studs off flush with the aluminum block.
Propane ain't gonna cut it, but need real care not to add too much heat w/ a real torch too.
Old 06-26-2015, 03:41 PM
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Flame wrench
Old 06-26-2015, 04:20 PM
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Originally Posted by NEBassMan View Post
Propane ain't gonna cut it, but need real care not to add too much heat w/ a real torch too.
Bull, propane will cut it. It will heat anything up on an outboard engine without a problem. You can also use Mapp gas, it's a little hotter than propane.
Old 06-26-2015, 04:21 PM
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I've heard of machine shops heating stud and then putting a candle on it. pushing candle on the stud forcing the wax into the block which lubes the threads. then weld on the nut.
Old 06-26-2015, 04:33 PM
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If you get to the point of drilling, use a reverse drill bit and it might catch the stub and twist it right ou.

Mike
Old 06-26-2015, 05:08 PM
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Depending which stud/location on block...I have had luck(on V-4 Crossflows) with a coreing bit with the inside diameter the same as the stud. It only works on studs where you have enough meat on the block to drill and helicoil. My guess is though.... since you have 5 to drill one are more will be in the narrow and you are headed for the machine shop or scrap pile. Pisser aint it.
Old 06-26-2015, 05:10 PM
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PS do not bother listening to those who will suggest every kind of drill bit in existance. Ive tried them all.
Old 06-26-2015, 05:16 PM
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Weld a washer that has an I.D. slightly smaller than the bolt diameter, then tack a nut onto the washer.
Old 06-26-2015, 05:26 PM
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Machine shop. Stainless in aluminum is a real pain. The corrosion actually fuses the metals. If it were just one you might find it worth fiddling with, but 5? It'll probably wind up in the machine shop anyway.
Old 06-26-2015, 06:00 PM
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There is a new chemical out there that is supposed to make PB Blaster look like WD40.. I'll try to find the name of it.
Old 06-26-2015, 06:03 PM
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First thought machine shop.
Old 06-26-2015, 06:21 PM
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AERO KROIL

The oil that creeps.

My Dad had center caps on his wheels that were held in place by stainless steel philips head screws. We thought we were done until we placed this stuff on them and let them sit overnight.

The wheels were aluminum and the bolts were stainless.

It worked for us.
Old 06-26-2015, 06:31 PM
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x2 on the Kroil. Might also try a series of firm taps on the ends of the studs w/a hammer to help loosen the corrosion.

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