Bolt head stripped while removing coolant pipe

2007 AE

While attempting to remove the coolant pipe to facilitate other maintenance, (FOM in USAF-speak), I stripped out the head on one of the bolts that holds the coolant pipe to the head. Thinking it might not be 100% gone, I tried an impact driver, this one that I probably picked up at Sears a decade ago <https://www.sears.com/craftsman-impact-driver/p-00947641000P>, and now the bolt is totally rounded out.

The bolt is too far down in a well to try to Dremel a slot in the head, though I haven't tried, and too far to grab it with needle-nose Vise Grips. What's my next step? I don't want to make things even worse. EZ-Out? I don't own any kind of bolt extraction tools, but Home Depot and Lowes are each 10 minutes away, plus there's a Fastenal store 15 minutes in the other direction. Both Lowes and HD seem to offer multiple brands, so I'm not sure what's good.

If it's going to be EZ-Out or similar, do I pick a size slightly bigger than the hex hole, now rounded, and hammer it into place? Do I need to drill first?

Thanks for any tips.

Can you drill the head off the bolt, remove the coolant pipe and use needle nose pliers to remove the threaded portion. Only problem might be if the threads are badly corroded into place. Then it could become tricky no matter how you attempt it. A little penetrating fluid and/or some heat might help.

Beat a slightly smaller SAE socket onto the head and use that to remove the bolt. You won't make the head of the bolt any worse and you might break the socket but it's worth a go. Use your impact driver but don't slam it. Hit it a bunch of times lightly. Might even try tightening the bolt a little bit first. It takes finesse. Stay away from easy outs as they can make a bad situation worse. You don't want to even think about breaking an easy out off in the bolt. I've seen many inexperienced mechanic turn a job upside down with a hardware store set of easy outs.

Centre punch the head, then try a left-hand twist drill bit. https://www.irwin.com/tools/drill-bits/left-hand-mechanics-length-cobalt-high-speed-steel-drill-bit-sets




sometimes you can get lucky and the drill bit will wind out the stud..if not, then tap it with a left hand twist tap..

https://us.misumi-ec.com/vona2/result/?Keyword=Left+Hand+Thread+tap&isReSearch=1

.thread in a left hand thread bolt, apply a lot of penetrating oil, let it sit for a few days, then gently try to undo it.

The problem is that the bolt is steel and the head is aluminum..bi-metallic action due to dissimilar metals has caused the corrosion

Its an Allen head bolt. So you would want to try a slightly larger bit if you went that route. Or, Ive been successful hammering a slightly oversized Torx bit into a rounded out Allen head. Problem in this case is you are hammering on the top of your cylinder head so you want to go kind of easy on the hammering. Id suggest getting penetrating lube on the bolt and try to heat the surrounding alloy without heating the bolt if possible. Grinding or drilling the head off will be tough down inside that hole, but eventually that may be the only recourse. Once you get the pipe off and the valve cover off you will have good access to put vice grips on whats left of the bolt.

Id stay away from the EZouts They are hardened and brittle. When you snap one off inside a bolt thats when you know that you are truly fucked. Up until then there are many better options like drilling out the entire bolt and then heli-coil.

Maybe a twist socket will remove it. Fits over the outside of bolt not inside. It has a twisted surface that bits on head. Woks on rounded and rusted nuts and bolts.

Might be tight if very little clearance between pipe wall. I've used these on rusted under size nuts and they work!!!

What Fred W said! Stay away from the easy out. Torx driven into the hole of the rounded out Allen screws has worked for me. Use the biggest torx you can. The impact from driving it in often frees up the frozen bolt. If the torx turns in the bolt when torque is applied you aren't any worse off than you are now.

I used an external screw extractor. Stupid easy.

SLK50 said:

I used an external screw extractor. Stupid easy.

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Hey SLK, please qualify that statement. I have used ez-outs, and a twisted socket to remove damaged screws/bolts. Never had any success with a reverse screw extractor (you know, electric drill with reverse thread extractor), so I'm interested to find out and an external screw extractor is? I like the idea of tapping a slightly larger torx into a rounded out allen keyway, sounds like the shizzle to me.

Thanks for all of the excellent suggestions. What I feel most comfortable with, at the moment, is driving a slightly oversized Torx bit into the rounded out head and going from there.

I hear, loud and clear, the advice to avoid going crazy with the Easy Outs. That, right there, might have saved me some pain.

"drill the head off the bolt - "I could _probably_ drill off the head of the bolt and remove the coolant pipe, but I'm concerned that there wouldn't be enough bolt material left for me to grab onto, so I'll save that tip for later.

"Beat a slightly smaller SAE socket onto the head" - this is a possibility, but all of my sockets have a slight taper to help them slide onto a bolt head or nut, so I'd probably want to grind that away in order to get a full bite.

Thanks for those and the rest of the tips. I'll let y'all know how it turns out. Hoping it doesn't go to hell in a handbasket.

SUCCESS!!

I authoritatively coerced a slightly larger Torx bit into the rounded hex head, then I first tried to remove the bolt with the impact driver. Absolutely no go. Next, I swapped the impact driver for the 3/8" ratchet. Sorry, grasshopper, you aren't strong enough to break it loose that way. I tried tightening, once, to break it loose in that direction, but still nothing. Taking a deep breath and flexing my best Popeye muscles, I tried again with the 3/8" ratchet. And...nothing. The first part of my hokey setup was a 1/4" socket over the Torx bit, because 3/8" didn't fit in the well, and then a 1/4" extension to get enough clearance to where I could go to 3/8". That poor 1/4" extension displayed some serious torsional flex, but the bolt didn't budge. Finally, grabbing yet another adapter, I swapped the 3/8" ratchet for the bigger 1/2" ratchet and gave it another go. Not a peep, so I took a couple of long slow breaths, calmed down, focused all of my thoughts and energy, and gave it everything I had. !!!SNAP!!! If the neighbors were awake two doors down, they probably heard it. If anyone happened to be on their front lawn 4 doors down, they probably heard it, too. Once broken loose, the bolt turned by hand. Upon removal, the threads look fine to me. No signs of corrosion or galling. Holy Mother of Pearl, that was a loud snap. I knew something came loose, but at first I didn't know what. It could have just as easily been that poor 1/4" extension giving up its smoke.

Many thanks to all of you! For the record, the Torx bit idea worked wonders, especially given how much freaking torque I had to apply to break the bolt loose.

Now I can remove the coolant pipe so that I can lift the AVCC to get enough slack in the plug wires so that I can replace the plugs. Oh, and the whole reason I'm in there in the first place, I'm entering week 2 of trying to troubleshoot a no-start condition. There are lots of threads on that topic, so I won't say more here. Thanks again!

With that much torque needed, you are lucky the bolt didn't shear - about two threads below the surface of the head!!

On all 3 of the FJRs that I've removed the coolant pipe on (in each case it was the first time the coolant pipe was removed on that bike), there was a "snap" when it broke loose, although thankfully, I didn't have problems getting it out. Lots of lock tight on those bolts from the factory. In each case, I did not run a tap in the cylinder head, but I did lightly buff the bolt threads to remove all residual lock tight.

Not really sure what Yamaha was thinking there - the squishy of the O-rings will act like a lock washer against vibration. No need to get stupid with it.

Next time I'm in the shop, I'm gonna check out my allen sockets to see if any of them are rounded at the ends. If so, those are getting chunked and replaced.

Regardless - I'm glad you averted what could have been a disaster. I enjoyed reading the suggestions from others, and I'm placing those in the bank for future reference.

I'm surprised they would use Loctite. There are lots of dissolved minerals (anti-corrosion agents) in antifreeze. It might just be residue from a bit of AF plus hundreds of heat cycles that effectively glued the bolts in place.

FSM does not call for thread locker on this.

RossKean said:

I'm surprised they would use Loctite. There are lots of dissolved minerals (anti-corrosion agents) in antifreeze. It might just be residue from a bit of AF plus hundreds of heat cycles that effectively glued the bolts in place.

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Plus with all the crap that collects in there it might simply be a corrosion between the head of the screw and the metal of the bracket, not with the screw threads themselves. I know I have to blow/scrape out all kinds of debris from the two recesses when removing the coolant pipe.

If you have a stubborn bolt like that, even very small like a brake bleeder, once you get something with a good bite on it grab your monster impact wrench, set the air pressure very low so that you can stop rotation with your fingers, and let the wrench tap away forward and reverse....and the bolt will give up after a while without shearing off..works every time...

I had a similar situation tonight, I was just removing mine in preparation for a valve check/adjust. I had the bolt about a quarter of the way out when it galled up and wouldn't move in either direction, ended up twisting the head of the bolt off. The motorcycling gods smiled on me tonight, I was able to drill it down the center and clean the threads with a tap.