Leon Speed

I would try good penetrating oil and a slightly larger XZN-bit, possibly with a impact driver.

sharknoob

I didn't say anything about drilling it out just sticking it in the striped out bolt head as a start. It allows you to use a larger size ez-out in the head of the bolt and does not make the bolt tighter in the hole. If it snaps off use a center punch to bust it up or move on to cutting the head off as chewy did

chewy8000

Sorry Jeff I mis-understood you. I still have never had any luck with Ez-outs you eventually end up where I did anyway.

Hilton

+1 - the hand impact wrench is great for stuck allen bolts - one with a 1/2" drive.

Just make sure you use it before you start to strip the head (i.e. if you feel the hex key sticking after it turns a mm or so, STOP. Took me far too many mistakes to learn that )

Garth S

If the rounded out allan head is still intact, select a slightly larger size Torx bit ( socket) ..... and drive it into the bolt head with a BFH: the torx teeth will cut new channels into the soft head, and the shock of the hammer blows will help break the corrosion bond on the threads. Use an impact wrench if available to remove.

As previously noted, soak in Kroil, etc before using the hammer.

fredfox

That is the way to do it, have done it many times. Stripped allen, hammer a torx in it. Use a hand held impact hammer wrench, 3/8 drive, you hold it in your hand and hit it, so it turns and puts down pressure at the same time.

Tails

With reference to Xlot post #19 and and Garth S post #20. When using the Torx bit and the impact diver, if the set bolt it jams, reverse the impact driver and re-tighten the bolt a little and then reset impact driver to undo the bolt. Use this method continuously in removing the bolt until the bolt is undoing freely.

This is the same procedure when using a tap cutting a thread into a blind hole, cut clockwise and reverse a little and cut again, this stops the jamming effect of the tap with the swarf. The same principle will apply with the reversal of the impact driver, it will stop the jamming of the bolt during extraction by the wedge of rust and aluminium oxide and prevent failure if torque is too great.

The penetrating fluid that I use is called "Reducteur H-72 Super Release Agent" and it is for ferrous rust,
howevre, it is also a lubricating agent and rust preventer in that imparts a coating on the surfaces.

Tails 1990 928S4 Auto

Jascd

There is an excellent chance the bolt will break no matter what you do. I had this happen to me a couple of months ago. Was a real gulp moment as I felt I was pushing my skills just to do the intake and was super careful not to break anything or drop anything into the engine or intake ports.

In the end i sent an SOS out to my mechanic who rocked over to my garage with his gas set and got heat onto the stub until it was pretty red and then let it cool. from there he got the vice grips on to it and gently started to work it around. It was coming free and he had just said we had "dodged a bullet" when it snapped flush with the engine. Harsh words were heard!

Another trip back to his garage for more tools and he came back with drills and bits. By hand and eye he drilled a small diameter hole all the way down the middle after first starting it with a centre punch. He then worked up to larger diameter bits until he was a mill or so short of the hole diameter. This was a tricky part, he then switched to an imperial drill bit that was a little bigger than the metric but still smaller than the thread diameter. While he was doing this I was on the other side of the engine keeping an eye on the drill to make sure it was staying vertical on all axis. He then got a tap and worked it down, then a thread chaser. We were able to preserve the thread and he gave me a nice new bolt to go in with a proper head and lots of antiseize. This job would not have been possible with the intake on. All up from the time he arrived to the time he left was about three hours. It would have been quicker if the car had been in his shop.

He also said don't use the easy outs but if you do and they break you can drill through them using a cobolt drill, sounds kind of cool but I would not want to have to do it.
Here is a picture of the stub.

jeff spahn

Oh man you did dodge a bullet, just a later, larger one.

jeff spahn

Well I guess my question is then should I take my water bridge off when I do the intake refresh just so I can take the bolts out and put them back in? PO changed out the thermostat 5 years ago so I know I don't have to do that (fingers crossed just for saying it) soon.

S4ordie

From what I can see from the pic there is not enough room to do things like getting an impact driver strainght on to the bolt head. Seems like all the fixes, short of putting penetrating oil on the bolt before beginning, are for when the bolt head has already snapped off and you've removed the water bridge. Just seems to me the best thing to do is to just remove the entire intake and do a few other WYAIT tasks.

AO

Yes, you should take it off. At a minimum you shoudl check the seal behind the thermostat as they have a bad reputation for having not been changed out/deteriorating. Plus it will give you a chance to lube up the bolts with pleanty of antisieze.

If you're going to Powdercoat your intake while it's off, you'll want to do the water bridge too, so take it off.

Bill Ball

One last bit of resuce information. Cobalt drill bits will take forever on an EZ Out, which are usually tungsten carbide. The best thing I found for cutting out broken EZ Outs or tungsten carbide thread taps are Dremel diamond-tipped points. These small bits will cut through tungsten carbide almost like butter with the caveat that the small diamond-coated ball end can come off the shaft if you use it more than 15-30 seconds at a time with light to moderate pressure, letting it cool off before going at it again. Or you can try to fracture the brittle tungsten carbide with a punch, as mentioned. Dave said it, your mechanic said it and I'll say it again - DO NOT USE EZ OUTS on broken bolts. They almost always snap and make the situation worse.

jeff spahn

Andrew, any reason not to replace the bolts with Stainless while I have them out?

Jerome Craig

BTDT with a suspension bolt ... and a 1/4" of the punch broke off and fused to the carbide chunk. I used a diamond tipped Dremel bit and cutting oil over a three day period to get it all out.