Help - sheared bolts in head
 

So this afternoon I thought I would do a simple valve cover gasket replacement. Unfortunately, in the process 6 bolts sheared off. 4 of them are sticking out from the head enough I think I can get them with heat and vice grips. However, 2 are just slightly above flush with the head and need to be drilled out. I thought maybe I could disconnect the engine mount and lift the engine enough to be able to drill them out, but I don't see how I can get access to the engine mount. Any suggestions on how I can get at these and remove them is appreciated!

I broke off the rear bolt in the drivers side I ended up cutting a drill bit in half and using a right angle drill and was able to drill it out. It was a massive pain in the butt though. Hopefully you can get to them without disconnecting everything.


Sent from my iPhone using Tapatalk

Thanks for the suggestion, will give that a shot

Honestly it’s going to be a long frustrating process. If I were to have to drill out bolts again- I’d probably just take it to a shop.

If you know anyone who can weld - you can see if you can weld a bit to the top and extract it that way though probably not if there’s not a lot of room on top

I am unfortunately in the exact same situation. This happens beacuse the its steel to aluminium and the bottom of the bolts are easily exposed to moisture so they tend to rust. You can still get the valve cover off as the valve cover is not threaded and get some vice grips on the bolt. Soak in penetrating oil for as long as possible before and you may just get lucky. Before you drill them out you can also try with a screw extractor.

Still no luck...the studs that were protruding are now breaking off and Im getting closer to having to drill. The problem is, even with an offset drill I dont have enough clearance. Thinking if I can just disconnect the engine mount, I can jack up the engine a couple inches to get at it, but dont see an easy way to do that. Any suggestions on unbolting the engine mount?

Never played this game on a Toyota, but have played it plenty. Don't waste time on e-z outs, all they do is break and make it more difficult. Get a good set of drill bits start small and work your way up in size. The bolt should extract prior to damage to the threads. Good luck.

Agree - easy outs are designed for screw heads. With bolts get a high quality drill bit for steel carbide tipped, diamond tipped etc

Along with what Charlievee said, if you can get a good set of reverse drill bits, you might actually get a bolt or two to begin backing out while drilling. Do the first pilot holes with standard bits, and switch to the reverse ones as you’re approaching the bolt diameter. They may just drill holes, which won’t hurt anything. But may be worth a shot.

IIRC the V8 has some hard lines along the passenger side firewall aft of the head, right above the valve cover fasteners . . . raising the engine is the ticket? Or lowering? If you cant get clearance for tools, then this is a problem. Even if you did get it dead on center, it could still be an issue with misuse of extractors or even broken drill bits. Im usually one to take the risk, but even so I have gone to a machine shop from time to time after a broken carbide bit in a sheared valve cover fastener in a head or for some other seized fastener.

As for attempting removal in-situ, the previous replies are pretty much on the money. However, welding would be risky on such a small fastener that is just above or flush to the machined surface of the head and I would only go with TIG and an operator that pretty much does it for a living. There is a not-insignificant risk that welding would damage the machined surface of the head, which could place the head completely out of machinable spec. TIG and operator skill mitigates this risk somewhat.

The only bit you should bother with for material removal is a carbide tipped or full carbide OAL bit in right hand. Reverse/left hand bits need to be able to flex a bit and are usually some type of high speed steel.

Extractors/EZ Outs are designed for use in the circumstance where the fastener shears due to over application of torque, not corrosion. So skip this all together as mentioned by other members. Good advice, dont get tempted into it.

Broken tooling needs a machine shop that can extract it or use a EDM/MDM/tool disintegrator. Pretty slick, there are portable EDMs, but these would not work here as the electrode needs to be on center with the fastener.

If the drills cannot be placed dead center, this is going to be a rough one. Nothing a time-sert couldnt handle.

This is definitely not the thread I wanted to see before I tackle my valve cover gasket this week... Especially since I've already sheared one bolt off in the block which makes me think there is some risk this happens to me.

Maybe I should just go spray all the bolts in penetrating oil *NOW*

Have not run into this in a while, must be a rust belt thing; salt causing a galvanic corrosion issue maybe?

Anyways, I would see if you can find a right angle drill (I think Harbor Freight has them rather cheap) that should help get the angles you need on some of the bolts (not sure which ones broke off on you, but I suspect the pain in the ass ones of course.) Get a set of reverse drill bits like others have said and start small, drill up, take your time. I would also get a file and a self-centering punch if you have one; the more you can ensure the drill bit is on center, the better it will be.

As for the engine mount bolts, they're 14mm and you can access them from the wheel well area; it's not particularly easy to get to one or two of them and I imagine if you're in NC that the rest of the vehicle is probably rusty so they will be a ***** to get loose if you can.

Post Note-

I should mention the thread pitch on those is 6x1.0mm so you won't want to go too much bigger than a 5mm drill bit or you might wipe the threads out.

Dremmel a cut for a standard screwdriver. Then heat them with a plumbers torch until they smoke, then screw them out. Heat is your best friend.

Patience, heat, and penetrating oil (50/50 acetone and ATF). I'm a bit of a pro at shearing off bolts so I've had some practice haha

After fiddling with something for 2 days, I would have just removed it and taken it to a machine shop. Using a drill and getting invisible metal shavings in the engine is just going to destroy both cams and all the cam caps, leaving you with a trashed motor.