Broke a bolt while doing my valve cover gasket

Broke the following bolt while screwing my valve cover back on after doing a new gasket. Can’t tell if oil is leaking near the missing bolt since I never really cleaned up the original mess. Suggestions? Maybe it’s ok without it? It’s too far down for the to just unscrew it with a vice grip or anything. Any chemical that might help loosen it if I use an ezout? I don’t want the chemical to harm the new gasket if it touches.

Left handed drill bits can help a lot. Start small, drill the next size and the next. If the broken screw doesn’t come out with the drilling, use an Easy-out. Also helps to heat the aluminum head while trying to extract since the aluminum expands more than the steel screw. Good Luck!

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I tried using a regular drill bit but couldn’t get it. But I just picked up a center punch at harbor freight that might help. Maybe some left handed drill buts in order as well. I broke it off because the torque wrench failed to click at 85 lb and kept going. The rest of the job, I just guessed the tightness. Is that generally ok?

Instead of using the gasket, use this instead.


The torque values may be in inch-pounds, not foot-pounds. You may be tightening them 12X what they are designed for.


Yeah, inch-lbs not foot lbs. It isn’t a head bolt, it s a valve cover bolt. As for just guessing, no. Many of us here can tighten by “feel” based on experience. Since you snapped off a small bolt, I’d say for you, at this point, that is not generally OK. In time you’ll get it but for now learn the difference between ft-lbs and inch-lbs and develop your feel.

Start by center punching the old bolt and drilling a pilot hole.

Then you can use one of these

and use the suggestion that @Mustangman offered of heating the area around the bolt to expand the aluminum. A small propane torch will get hot enough.


DO NOT use a regular drill bit, chances are the bolt isn’t bottomed out in the hole, using a regular drill bit will just screw it into the hole farther once the bit grabs.

Get a left hand bit.

Isn’t this an aluminum block? Anytime I’ve ever over torqued a bolt in aluminum I stripped the block before I broke the bolt. Fortunately not much experience with this. Can you really see the remains of the bolt in there?

Yeah I purchased some bolt removing bits from Harbor Freight and the damn thing came with crappy regular drill bits. You’d think they’d come with left titanium but no. I went back to get the correct ones and they said I could return the set once done(the “ezout” since it came with the wrong drills.But yeah I got the bolt out, it was a bit tricky but I had to hammer in the thing in and unscrew using a vice grip. It was pretty easy for the most part. I did spray some wd40, but not much.

Good for you for getting the bolt out. If you run into tricky problems like that in the future, an auto-machine shop has the specialty tools and expertise to fix that kind of problem in a jiffy. Given the risks you take on by inadvertently turning a minor, inexpensive problem into a major-expense problem, it is often better to just tow the car to the machine shop and have them do the repair job. The machine shop fee should be pretty reasonable for something like that, likely less than $100.

Note: If you still have an oil leak afterward, you may have damaged the valve cover, assuming that you overtightened the bolts b/c of the foot-pounds vs inch-pound mix-up. A junk-yard valve cover is probably the best bet in that case.