Heat an aluminum head?

After adjusting the valves in my E30 for the first time, while carefully torquing the valve cover nuts, I snapped a valve cover stud. The PO has done so much E36 M3 to this car, he must have torqued it past yield  previously.  I put one of those Irwin EZ out things over the top of it. That grabbed it well enough, but it broke again! Idk if I was still working on the weakened part of it or the PO used loctite on the stud or what. I've proactively replaced the other studs and they all came out easy.

i know the canonical way of pulling this out is to weld a nut to it, but I can't weld and I don't have a welder. 

I think if I hit it with a Mappro torch I might be able to unscrew it w vise grips, but I'm afraid of warping the head. Is this a real risk? Apparently I6 heads can warp easily cause they're so thin, but I have no idea if a Mappro torch would be hot enough to be a problem.

What does GRM think?

When people say the head will warp they mean the mating surface on the bottom of the head to the block. Which I don't think is as big of a deal on the m20 as it is on the m50.

A small hand torch would be what I'd try if I didn't have a welder. If nothing else, you'd need that to help break loctite loose if the PO used red.

Funny enough, I had a nearly exact same failure on my N52. My extractor just snapped the bolt it was in there so tight. I ended up drilling it and using a male type extractor. The first attempt was with a small extractor, and it also snapped. Drilling that out sucked royally, but then the larger extractor worked. Kinda. The bolt sheared AGAIN deeper into the head, but then it let go pretty easily when I drilled it out. 

TL;DR: drill and use the biggest male type extractor you can. 

First heat, next left handed drills, then the extractor.

stafford1500 said:

First heat, next left handed drills, then the extractor.

Thanks for the reminder. We should all have "left handed drill bits" on our Christmas lists.

stafford1500 said:

First heat, next left handed drills, then the extractor.

I'll edit my post to say left-handed as well. My extractor kit came with a bunch of sizes as well as matching left-handed bits, great for Christmas!

I have a nice set of left handed extractor bits. I haven't used them successfully yet, but I'll give it a try. This is by far the most accessible and least corroded place I've tried it so I should be able to get it centered well.

thanks for the tips, definitely gives me less worry about heating it

In reply to evelynjacob116 :

What does this have to do with the subject being discussed

Make sure you use Grease or something to catch any filings before they go down in the engine.

Shaving cream can work well and then use a shop vac to suck it up.

While drilling or welding a nut on is usually the fastest way to remove steel bolts in aluminum(drill bit and extractor is probably the best option in this particular scenario) an alternative is using alum to dissolve it.  Alum won't attack aluminum or most other non-ferrous metals, but will dissolve steel.  It's not a quick process, but sometimes the wait is worth it especially if you're working with unobtainum parts.  It's cheaper and less stressful than potentially having to fix the damage caused by mistakes/accidents while trying to drill them out.

Handy for small diameter fasteners stuck deep inside blind holes or places that it's tough to get a drill bit or welder. 

It's especially useful if the fastener is stuck because it is badly corroded.  If you manage to get an easy out to bite or weld a nut on you're likely to destroy serviceable threads in the aluminum part as the corrosion from the fastener jams up and can tear them out.  If you dissolve the fastener usually a cleanup pass with a thread chaser is all that's needed.

Where alum is most useful is if the worst case happens and you break off an extractor or drill bit in the fastener you're trying to remove.  Trying to drill out the hardened steel usually results in tools being thrown across the shop and/or damage to the part from wandering drill bits.

You can find alum at the grocery store in the spice or pickling isle.  Check the ingredients, and make sure it contains potasium aluminum sulfate or ammonium aluminum sulfate.

Mix up a concentrated solution and soak the stuck fastener.  Mild heat will speed up the reaction, but depending on the size of the stuff you're trying to remove it can take hours or days. 

Usually In the case of a stuck bit or extractor, a few hours of soaking is enough to loosen them up enough to pull out the broken pieces.  Depending on soak time and luck, enough of the fastener will have dissolved for a new extractor to work.

If you're trying to completely dissolve a stuck fastener it can take a few days.  Drilling the the center of the fastener out with a small diameter bit will speed up the process by giving it more surface area.  

The hardest part is rigging up a container to hold the alum solution over the fastener.  Usually it involves putty and assorted tubes, funnels, or cups. 

Here's a good blog post that goes into more detail and has some ideas on how to rig up a container:

https://www.snaderflyby.com/dissolving-steel-out-of-aluminum-with-alum-powder/

Woah that's fascinating. Hopefully it'll drill out easy (turns out my left hand bits need sharpening, drill doctor is on the way!) but I almost want to try this in the "work smarter not harder" vein. Seems like it could be challenging to rig up, we'll see what happens.