Broken Bolt On Valve Cover: 6 Ways To Fix

If there is a broken bolt on valve cover, it could cause a major problem, because your valve cover might leak. In this article, learn how to fix this problem in six different ways

The valve cover is located on the top of the engine, i.e., above the cylinder head. It usually comprises plastic or metal and is connected to the cylinder head by bolts. 

You will find a valve cover gasket between the cylinder head and the valve cover, and the whole unit helps keep the oil on the engine’s interior.

But sometimes, the bolt can break, which leads to oil leakage.There are various reasons for broken bolts on valve covers, like incorrect torque, overtightening, or putting bolts in the wrong order.


Broken Bolt On Valve Cover


Will a Valve Cover Leak With One Broken Bolt?

Yes, a valve cover can leak with one broken bolt. The bolt helps to keep the valve cover in the proper position. But when one bolt is worn out or broken, you will find oil leaking from the engine. 

Oil is quite essential to lubricate various parts of the engine. Oil leakage can cause extra friction on the engine’s moving parts, which can lead to overheating. 

You will also experience other symptoms when a valve cover bolt is broken. We are listing some of them below.

  • The burning smell of oil
  • The engine will start to run rough
  • Poor acceleration
  • Oil spills in the garage
  • Lessen engine power
  • The valve cover will be covered with dust and dirt.

A broken bolt can be your greatest nightmare. Fortunately, there are various methods by which you can remove the broken bolt. But the most effective method is to drill into the center of the broken bolt and take the bolt out with the help of a screw extractor.

We recommend you not try any method if you don’t have experience removing bolts. 

Why does Valve Cover Bolts Break?

#1. Incorrect Or High Torque

Some car owners try to polish the valve cover from time to time or change the valve cover gaskets themselves. But putting the valve cover bolts in the correct place and order is pretty challenging. The torque value should be almost 43-78 inch lbs. If you overtighten the bolts, it can result in cracks, and the bolts break.


A torque wrench can be used to fasten the bolts and provide torque to 7 ft/lbs. The best option is to use one fourth-inch ratchet to prevent the bolt from overtightening. Using a ratchet, you can quickly know when the bolt will start to overtighten.

If the valve cover bolt breaks then take the vehicle to the mechanic. He will replace the bolt with a new one.


Broken Bolt On Valve Cover


#2. Failure Of Bolt Tightening Order

If you fail to tighten the bolts symmetrically, the valve cover bolts will experience plastic deformation and stress, and consequently, they can break.


You need first to choose the correct valve cover and gasket. Your second duty should be putting each bolt in slots till they fit correctly on the valve cover.

You have to tighten all the valve cover bolts in an alternate pattern. You should start from the middle and then move outwards. However, ensure that the bolt torque should be 7 ft/lbs.

How Do You Fix a Broken Valve Cover Bolt?

The valve cover bolt can break because of under-tightening, overtightening or incorrect torque. You need to replace the bolt with a new one when it breaks. But you need first to remove the damaged portion from the hole.

Depending on the bolt damage, you can use any of the methods discussed below.

Below are a few tools you may need to remove the broken bolt from the hole.

  • Center punch
  • Screw extractor set(left hand)
  • 1/8inch bit and 3/16 inch drill bit
  • Drill machine
  • WD-40
  • Socket wrench
  • Pliers
  • Vice grip

It’s wise to buy a bolt extractor kit for removing the bolts. The set will have all the necessary tools by which you can remove the broken bolt easily from the hole.

Method 1: Use Vice Grips

The shank or bolt shaft will be visible if the bolt has been broken from the head area. You need to hold the bolt by the vice grip and turn in a counterclockwise direction to loosen the bolt. You can then pull the bolt from its base to remove it.

Method 2:Use Punch, Screw extractor, And Drill Bit

  • Insert the punch into the bolt hole and strike its back with a hammer. The purpose of the punch is to mark the center of the broken bolt.
  • Start Drilling almost on the center of the bolt.
  • You can use WD-40 spray to make the work easier.
  • You may be lucky enough that it will push the bolt immediately. But if you are not fortunate, then follow the methods below.
  • Use a left-handed drill bit. It will start drilling in a counter-clockwise direction or drill leftwards. This drill bit is used to add enough torque to remove the bolts from the hole.
  • Drill enough that you can extract the broken bolt with a screw extractor.
  • Tap the screw extractor inside the bolt hole.
  • Take a spanner and apply pressure on the screw extractor. You have to rotate the screw extractor and turn it in an anticlockwise direction.
  • It will extract the broken stud from the bolt hole.
  • But if you are not successful, then use a larger drill bit. It can be either a right-hand drill bit or a left-hand drill bit, and try to remove the bolts from the hole.
  • Follow this method if you have a habit of extracting bolts from the hole. If you do something wrong, then it can damage the engine casting.


Broken Bolt On Valve Cover


Method 3:Drill And Retap

  • The method involves drilling and retapping. You must apply this method when the bolt breaks at the thread section.
  • Drill the hole and retap the threads to extract the bolt.

Method 4:Welding

  • This method involves welding on the broken stud. It is applicable if the bolt of the valve cover is broken at the head region.
  • Once you do welding, put the socket, twist it and try to remove the broken bolt.

Method 5:Tapping 

This method is applicable if the bolt is broken from the shank area. You need to tap the head and exposed shank and remove the bolt from the hole.

Method 6: Use Die Grinder

Use a die grinder for hogging the entire area, welding, and then redrill on the bolt hole. Now use the correct size tap to remove the broken bolt.

Frequently Asked Questions

#1. How do you get a broken bolt out of a valve cover

Purchase a reverse drill bit whose diameter will be almost one-half of the broken bolt. Now start drilling with that drill bit. If you are lucky, the friction will be enough to unscrew the bolt.

However, if it does not work, you can buy a set of screw extractors from the market. You have to drill a hole at the center of the broken bolt and then use a screw extractor to remove the bolt.

#2. What to do if the bolt breaks off in the hole?

You need first to purchase the bolt extraction kit from the market. You have to follow the below points, then.

  • Mark the center of the bolt and tap it with a hammer.
  • Now drill at the center of the bolt where you have done marketing. You should use the left-hand drill bit. It is because it will turn in the opposite direction of the broken bolt, preventing overtightening of the broken bolt.
  • Now the right size screws extractor kit and removes the broken bolt.
  • You will find metal filling inside the bolt hole. Remove it by using compressed air.


Broken Bolt On Valve Cover


#3. How do you remove a broken bolt without an extractor?

  • Mark the exact middle point of the broken bolt.
  • Start drilling at the center of the bolt.
  • You need to first use a small drill bit, mainly of 3.4 mm, and then increase the size of the drill bit until you see the threads of broken bolts.
  • Take the correct size tap and remove the broken bolt from the hole.

Wrap Up

The valve cover is affirmed to the cylinder head by a bolt. If the bolt is broken, the valve cover becomes loose, allowing oil to come out from the highly dangerous engine. 

The bolts can get broken when they are over-tightened or too much. Well, your first will be to remove the broken bolt from the hole. 

You can follow any of the methods discussed above for removing broken bolts. If you don’t know much about it, don’t try. Take your vehicle to the nearest mechanic to remove the broken bolts. It would be much better than completely breaking the bolts and getting into a much bigger problem.

Thank you for reading this article!

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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