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Need help extracting broken bolt from engine

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Old Mar 2, 2022 | 11:02 AM
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C300 2010
Exclamation Need help extracting broken bolt from engine

Hi everyone,

So one day I turned on my car and heard a weird noise but I thought maybe it was from another car next to me. Then once or twice the steering felt weird so I popped the hood and saw that one of the bolts that hold the belt tensioner pulley has broken off.
I tried drilling it to get the extractor to pull it but the extractor wasn't sticking (I never dealt with a broken bolt before) but I didn't go a lot into it as I was afraid of screwing things up.


I took it to a shop and they quoted me $450 to pull out the bolt and $400 to change the pulley and everything else for my belt. My belt and the parts for it have a lifetime guarantee so I'm just going to send them back and get a new one.

Does anyone have any tips on how to get the broken bolt out? Does anyone have any tips or input on what I should try?

I need to get my car up and running in the next 8 days and I do not have the money (and I really mean that) to pay someone that much to get the broken bolt out.


this is the bolt but but this was before I drilled a little into it
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Old Mar 2, 2022 | 12:55 PM
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This place is a joke.
Pay a professional to do it before you create a huge disaster. Those bolts don't just randomly break off, you did something wrong to cause it. The fact you are asking how to repair shows you're already in over your head.
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Old Mar 2, 2022 | 01:03 PM
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C300 2010
The car has over 130k miles on it so the bolt was old and he said the belt was probably also putting a lot of tension on the pully but I had videos with the belt running and it was not showing any sign of putting a lot of tension on it.

I also had to fix the ESL, which was way over my head. Either way, if I could pay someone to do it, I would. I'm not being cheap here when I'm saying that I truly can not afford it.
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Old Mar 2, 2022 | 10:48 PM
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Originally Posted by Logan_Volcan
The car has over 130k miles on it so the bolt was old and he said the belt was probably also putting a lot of tension on the pully but I had videos with the belt running and it was not showing any sign of putting a lot of tension on it.

I also had to fix the ESL, which was way over my head. Either way, if I could pay someone to do it, I would. I'm not being cheap here when I'm saying that I truly can not afford it.
There is no way whatsoever that the serpentine belt can break that bolt. $450 to extract a bolt seems high, IF your efforts to get it out didn’t make things worse. Consult a general machine shop or an engine shop to maybe get a lower price. But that’s a minimum $200 job.
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Old Mar 2, 2022 | 11:08 PM
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Originally Posted by Odd Piggy
There is no way whatsoever that the serpentine belt can break that bolt. $450 to extract a bolt seems high, IF your efforts to get it out didn’t make things worse. Consult a general machine shop or an engine shop to maybe get a lower price. But that’s a minimum $200 job.

That's what I was thinking. Idk how the hell a belt can break a bolt and also everything else looks perfect but he wants to change belt, rollers, tensioner and all. The belt alone is only $20.

Sigh* I'm so frustrated. He charged me $95 just to tell me the bolt is broken.

So anything you'd recommend as an extractor or anything else? I can't weld and that's scary so that's out of the question. I'm taking out the other bolt just to see how deep long the bolt is and how far I can go in with a drill.
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Old Mar 3, 2022 | 12:19 AM
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What you need is a handy person with a mig welder to weld a nut on to the end of the bolt then unscrew it.
Have a look on tube and you will see what I mean.
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Old Mar 6, 2022 | 09:00 PM
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Can you get a drill with a bit in this area ? If so you need a decent cobalt or carbide drill bit 1/2 the diameter of the broken bolt shaft. Prelub area over night with PB Blaster or Kroil's, better yet. You need a center punch to dimple the center of the bolt so the drill bit won't wander..the attached Amazon item has an inexpensive kit with left hand bits and extractors. Sometimes the left hand bit will loosen the broken stud by itself. A hole 1/2 the diameter is the max, otherwise the extractor may compress the threads even more. Get an extra drill bit if you can..they break if you press too hard.

COMOWARE Screw Extractor & Left Hand Drill Bit Set- Broken Bolt Remover HSS M2, 10pcs with Metal Index Case


The MIG welded nut is good..a little tricky if the broken stud is below the surface.
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