So I just went to change my idler pulley, put the new one on, and tightened the bolt down...and I started to tighten it hard to make sure it was good, and I knew I shouldn't have kept going, but I was an idiot and did and now the tip of the f***ing bolt snapped inside the head

Any ideas on how to get the little piece out of there???? I can get a new bolt but it doesn't help anything if I can't get that little sh*t that snapped off inside the head. Please help!

 

Sears bolt remover

 

Or you can drill a hole through it and buy a reverse thread bolt remover. Last resort is to drill it out but you risk ruining the threads since the steel of the bolt is much harder than the soft aluminium head but I guess you could put a helicoil in.

I went through this learning curve when I got my first proper socket set. Luckily I only snapped a throttle body bolt which was easy to drill out and replace. Buy two torque wrenches. Get one in the range of 5-40Nm and a larger 40-200Nm or the equivalent in imperial, find the appropriate torque and never snap a bolt again.

 

Yeah I knew I should have waited and used a torque wrench but I was impatient and just wanted to get it done and I could shoot myself for turning a $20 repair into a huge problem, STUPID STUPID STUPID STUPID STUPID STUPID STUPID

The problem I've run into from looking at it is that the piece that snapped is very deep inside the cover. I told my indy mechanic about what I did and he told me I could try to drill it out but be very careful because the timing cover is made of magnesium and is strong but very brittle. And if I crack the timing cover and have to replace it...$660 just to get the part, and his supplier only has one in stock that's actually in the USA right now, and if he sells that one and needs to get one from Germany later on he can, and I don't know the cost, but it would take some time to get.

I drew a little sketch of the situation. I measured the distance of bolt remaining with the pulley in it to figure out about how deep the little piece is stuck inside the hole. I'm getting 4" from the back of pulley to location of the shear. It was an almost perfect 90 degree shear.



I was talking to my friend about this and he was thinking we could get a really long high carbon drill bit that's small enough in diameter and tap the center of the bolt, then get a reverse thread bit and see if it catches enough to pull it out.

The other thing which my mechanic was suggesting as a possibility was using a heli-coil or something and tapping it and using a different size bolt, but I didn't really understand what he was saying, I guess I need it drawn out to understand. And he was also saying I probably couldn't do that because of the little nub that fits into center of the pulley.

Hopefully beginner DIY'ers can take a lesson from this: ALWAYS USE A TORQUE WRENCH AND BE PATIENT! I had to learn this the hard way.

 

idler pulley broke today and got a new one at the stealership installed after a few minutes torqued it at 25nm ..finally im ready to start my car then i thought maybe i should tighten it more to 35 nm just to be sure and voila the bolt SNAPPED!!!!!!! WAAAAAAAAAAAAAAHHHH!!! STUPID ME ALSO


c230 mulac can you share how where you able to extract the bolt ?? or anyone from this forum who had the same experience ? i'm so confused what to do cause i really needed my car to go to work.

 

That bolt is supposed to be very low torque

 

#%&#*@*! I just broke the head off the idler pulley bolt trying to get it off. Did anyone else have any luck with their broken bolts? Or can I change the belt without removing the bolt and hope that I never have to replace the pulley?

 

If you broke the head off the bolt the pulley will just slide off.

 

I realized I never followed up on this. blackcore, I'm sorry I never saw your response to help you out. But here is what ended up happening.

So the head of the idler pulley bolt has a step down to a smaller diameter circle that one side of the pulley bearing sits on and spins. On the engine side, the pulley bearing sits on the outer ring of the hole where the bolt goes, which happens to be the top of the water pump. As shown in my above sketch, it's actually about a 4" deep hole that nothing screws into, just provides a pathway for the idler pulley bolt to go and it actually screws into the head deep down inside there.

I was actually never able to get the piece of bolt that's snapped deep inside there. So what I had to end up doing is this:




You need to tap the pulley bolt head because that has the smaller diameter ring that the pulley rides on. My buddy and I did it with me holding the bolt by the smaller ring with channel locks and him drilling it straight through the top and once drilled through the shank will just break off on its own. We tapped that and the water pump hole with the same size tap, then went to Home Depot and found the right size bolt (we took the head of the pulley bolt that was tapped to verify fitment. Put everything back on and tightened until we felt resistance and took it maybe a half turn past that, checked if the pulley spun. Backed it out a bit until the pulley spun freely to find that point. It takes a little finesse to get it tight enough so it won't go anywhere but you can't tighten it so much that you're putting a lot of pressure on the pulley bearing and restricting its ability to spin freely.

The biggest PITA with this solution is when I had to replace my water pump a couple months ago, I had to retap the hole in the new water pump. I was hoping maybe with the water pump removed I could reach far enough in there to pull the old bolt out but I couldn't.

 

Also, @Moxostoma, if you broke the head of the bolt off you are going to need to get a new bolt. If you just broke the head of the bolt off you should be able to grab the shank with some pliers or channel locks and spin it back out so you can get a new bolt. They're about $6-7 from the dealer if I remember correctly. I bought one thinking I could get the old part out but never did so I have a spare idler pulley bolt sitting around.

 

I wasn't clear in my description. Most of the head of the bolt is broken off but the flared part is intact and holding the pulley on. I'm afraid to try to remove the other pulley bolt.

I just realized that this is an AMG thread. I have a C230 Sport. My bolts may have a different design than yours.

 

Other pulley bolt??? What year C230 (need to know whether it's the 4 or 6 cyl engine).

I'm not sure what you mean by it's still holding it in by the "flared part," but if your bolt is damaged in any way I would recommend getting a new bolt. Call the local dealer and get a new bolt, use a torque wrench, problem solved.

By the way, to answer your original question, yes you can change the bolt without removing the pulley. That's the purpose of the belt tensioner, so you can take the belt on and off. Now that I think about it, I bet the reason the bolt broke trying to get it off is because you still had the force of the belt on the pulley and the bolt.

Take a look at this: http://www.pelicanparts.com/techarti...oly_V-Belt.htm

They use the center of the pulley torx to relieve the tension, but there's actually also a nub on the bottom left of the tensioner pulley that fits a 17mm socket and you can rotate it counter-clockwise and when you do that the tension is relieved and you can slip the belt off of the idler pulley and then it's just free to take off. When you put it back on, I recommend routing it along where it's supposed to go and have it off of the idler pulley up top. Holding that part of the belt with your left hand, use your right hand to rotate the tensioner counter-clockwise again enough so that you can slip the belt back onto the idler pulley and there you go, done!

You can't remove any of the pulleys without taking the belt off first. This is just an assumption, but it sounds like that was the mistake that broke the bolt.

 

You're exactly right, I was trying to remove the bolt. And the bad thing about it is that I've done this before and somehow remember removing the pulley. I assume the bolt is reverse threaded so I was tightening the bolt until it gave way. Thank goodness I didn't pursue a career in auto repair.

Here's a photo of the pulley and broken bolt. I don't see the nub you are talking about. This is on a 2000 C230.

 

Oh so it's a w202 chassis, not w203. Well I'm not sure if it has the nub then, I figured it was w203 since you're in the w203 forums.

Unless they decided to do some funky voodoo with the w202 chassis it should not be reverse threaded. So basically it sounds like you were turning the bolt the wrong way and over-torquing it and it broke.

However, there should be a belt tensioner somewhere, not sure what the belt diagram on that engine looks like, but with ANY car there is always a belt tensioner where you relieve tension to pull the belt off. Once the belt is off, then you can remove whatever pulleys you want.

 

BTW, the nub wouldn't be by the idler pulley if there is one, it would be on the belt tensioner itself.

 

Also I hope you are replacing that belt because it is DONE.

 

After all this it was simple. What I thought was a metal plate was actually a plastic cover. I pried it off and found a nut that I could use to pull the tension off the belt and change it.



The splined end of the shaft is convenient but if the nut is tightened it can be used instead.

Thanks for your help.