Snapped Rocker Cover Bolt?

[Bhavick]

Hi,

I was retighening one of the rocker cover bolts to 10NM and as the bolt was getting tighter the head of the bolt snapped off leaving the thread part of the bolt stuck inside. Any ideas of the best way to remove this please? This is what is left of the bolt the rest is stuck inside the thread of the cover i believe see image in link:

IMG_3109.jpg

drive.google.com

Thanks

 

[jimbote]

Most times, a torque snapped bolt will come out with just a sharp punch. I would try to work it out gently first.

 

[Bhavick]

Most times, a torque snapped bolt will come out with just a sharp punch. I would try to work it out gently first.

How would you work it out gently when there is no head on the bolt?

 

[pedroYUL]

Nothing to grab on if you take the cover off again? I would try locking pliers first if possible

 

[[486]]

How would you work it out gently when there is no head on the bolt?

sharp punch allows you to scratch at the shank in the hole

 

[BobnOH]

You'll need to remove the cover, then you should be able to twist the broken stud out.

 

[Bhavick]

You'll need to remove the cover, then you should be able to twist the broken stud out.

OK thank you i think something like this is beyond what i feel comfortable doing so it's a mechanic job i think!

 

[JETaah]

Left handed drill bit and reversible drill of course.

 

[Nuje]

I was retighening one of the rocker cover bolts to 10NM...

I'm guessing you missed the part where it said that the rocker cover bolts (this is a PD engine you're working on, right?) are single-use / "replace every time".

If not, and this is a new bolt, then you should probably look at re-calibrating your torque wrench.

 

[jimbote]

I'm guessing you missed the part where it said that the rocker cover bolts (this is a PD engine you're working on, right?) are single-use / "replace every time".

If not, and this is a new bolt, then you should probably look at re-calibrating your torque wrench.

Rocker cover = valve cover. These are NOT single use bolts. You're confusing these with cam cap bolts. But yeah, torque wrench calibration much needed. Honestly, I've never torqued these, as they're positive stop bolts. Just snug is good enough.

 

[Bhavick]

Left handed drill bit and reversible drill of course.

Thanks for your reply, do you think a set like this would be suitable for removal?

6pc Helix Type Screw Extractor Set with Tap Wrench | AK721 | Sealey

Lifetime Guarantee - High quality alloy steel. Rapid acting helix aids screw removal. Includes tap wrench. Extractors supplied in storage case.

www.sealey.co.uk

I'm just concerned that size of these extractors might be to big and that there isn't much surface area to actual screw into as it's only the thread part of the bolt that's stuck inside the cylinder head and it seems a pretty clean snap as in there isn't anything sticking out that i could grab on to to undo it.

I'm guessing you missed the part where it said that the rocker cover bolts (this is a PD engine you're working on, right?) are single-use / "replace every time".

If not, and this is a new bolt, then you should probably look at re-calibrating your torque wrench.

yeah i'm fully aware that these are not single use bolts. I brought a new rocker cover gasket and new bolts from darkside a while ago and took it to a home mechanic who fitted it for us, he applied sealant round the edges etc but he never torqued the bolts down to 10nm as it says in the haynes manual here in the UK because he said these are crusher bolts and they can only be tightened so much and after a point they can't be tightened anymore so he just did them hand tight however after we got the car back it was still leaking oil so we thought if we go round each bolt and torque them up to 10nm then that might help solve the oil leak however by mistake we set the wrong torque setting and ended up snapping the head on one of the bolts, That's how this has all happened. Yes it is PD engine.

 

[JETaah]

Thanks for your reply, do you think a set like this would be suitable for removal?

6pc Helix Type Screw Extractor Set with Tap Wrench | AK721 | Sealey

Lifetime Guarantee - High quality alloy steel. Rapid acting helix aids screw removal. Includes tap wrench. Extractors supplied in storage case.

www.sealey.co.uk

I'm just concerned that size of these extractors might be to big and that there isn't much surface area to actual screw into as it's only the thread part of the bolt that's stuck inside the cylinder head and it seems a pretty clean snap as in there isn't anything sticking out that i could grab on to to undo it.


yeah i'm fully aware that these are not single use bolts. I brought a new rocker cover gasket and new bolts from darkside a while ago and took it to a home mechanic who fitted it for us, he applied sealant round the edges etc but he never torqued the bolts down to 10nm as it says in the haynes manual here in the UK because he said these are crusher bolts and they can only be tightened so much and after a point they can't be tightened anymore so he just did them hand tight however after we got the car back it was still leaking oil so we thought if we go round each bolt and torque them up to 10nm then that might help solve the oil leak however by mistake we set the wrong torque setting and ended up snapping the head on one of the bolts, That's how this has all happened. Yes it is PD engine.

The screw is 6mm, right?
The smallest in the set seems to have that covered.
A lot of times if you use a left handed drill bit (4mm for example) the friction alone of reverse drilling will unscrew it. If the screw was broken while mounting the cover chances are the screw wasn’t bottomed out in the hole when it broke and it may well easily unscrew providing that you can get a grasp on it to spin it.

 

[jmodge]

Maybe PD bolts are different than ALH, but the ALH cam cover bolts do stretch and are unable to handle the specified torque, will keep turning and will snap off. I would imagine because of being over torqued at some point. I've compared ones I've removed to new bolts and found a few that have stretched.

 

[Bhavick]

The screw is 6mm, right?
The smallest in the set seems to have that covered.
A lot of times if you use a left handed drill bit (4mm for example) the friction alone of reverse drilling will unscrew it. If the screw was broken while mounting the cover chances are the screw wasn’t bottomed out in the hole when it broke and it may well easily unscrew providing that you can get a grasp on it to spin it.

Yes they are M6 bolts, these are the ones in the link:

1.9 TDI 8v PD Engine M6 Rocker Cover Retaining Bolt

Darkside Developments is a UK based diesel tuning company, specialising in VAG (VW, Audi, Seat and Skoda), BMW, MINI & Porsche Diesel Vehicles

www.darksidedevelopments.co.uk

I've checked the rocker cover without removing it by poking something down into the bolt hole and all i can see is the thread part of the bolt stuck inside the cylinder head but it doesn't look there is anything at all to grip on to to undo it, in fact it looks like it's cleanly snapped off.

 

[JETaah]

Yes they are M6 bolts, these are the ones in the link:

1.9 TDI 8v PD Engine M6 Rocker Cover Retaining Bolt

Darkside Developments is a UK based diesel tuning company, specialising in VAG (VW, Audi, Seat and Skoda), BMW, MINI & Porsche Diesel Vehicles

www.darksidedevelopments.co.uk

I've checked the rocker cover without removing it by poking something down into the bolt hole and all i can see is the thread part of the bolt stuck inside the cylinder head but it doesn't look there is anything at all to grip on to to undo it, in fact it looks like it's cleanly snapped off.

What I’m saying is that the drill will grasp it.

 

[Bhavick]

What I’m saying is that the drill will grasp it.

OK i'm willing to give it ago but i do have some questions as I've never done this kind of thing before. So what you've said so far is use a left handed drill bit that is 4mm. Will a generic metal drill bit do or does it need to be made of a certain material as to not the damage the bolt? Also i know you mentioned just reversing it out but surely you need to do drill in to slightly so the drill catches on the bolt and then turn it counterclockwise to remove it or am i wrong? Also is it best to remove the entire rocker cover or you think if the drill bit is small enough i could remove it with it still on?

Thanks

 

[BobnOH]

From experience center punching and drilling a 6mm bolt is difficult. Not familiar with what engine you have but I think removing the cover would be easier.

 

[JETaah]

OK i'm willing to give it ago but i do have some questions as I've never done this kind of thing before. So what you've said so far is use a left handed drill bit that is 4mm. Will a generic metal drill bit do or does it need to be made of a certain material as to not the damage the bolt? Also i know you mentioned just reversing it out but surely you need to do drill in to slightly so the drill catches on the bolt and then turn it counterclockwise to remove it or am i wrong? Also is it best to remove the entire rocker cover or you think if the drill bit is small enough i could remove it with it still on?

Thanks

You do want to damage the bolt. That is the idea. Put a hole in it and in the process perhaps get an edge on it and it will be screwed out of the hole.
Look, this may not be a job that you will be comfortable with. This is what I would do given the task. It does take a bit of skill and and a sense of knowing when to stop and reassess the situation if things are not going well. You definitely do not want to break a drill or EZ-out tool in the end of the screw.
Left hand drill bits are usually not in stock at the typical home improvement stores. They are on line somewhere most often in sets.
Most battery powered hand drills these day are capable of being run in reverse.
You could use a regular right hand drill bit but it will probably run the broken bolt further down into the hole. And that is OK if you have the EZ-out tool to retrieve it once the hole is drilled. From the looks of it you might have to fashion an extension for the tool to clear the blocks and injector parts that are in the way.

Leaving the cover on will help prevent the shavings from falling into the engine. You just have to be careful not to damage the plastic cover. They are not cheap.

 

[P2B]

I brought a new rocker cover gasket and new bolts from darkside a while ago and took it to a home mechanic who fitted it for us, he applied sealant round the edges etc but he never torqued the bolts down to 10nm as it says in the haynes manual here in the UK because he said these are crusher bolts and they can only be tightened so much and after a point they can't be tightened anymore so he just did them hand tight however after we got the car back it was still leaking oil so we thought if we go round each bolt and torque them up to 10nm then that might help solve the oil leak however by mistake we set the wrong torque setting and ended up snapping the head on one of the bolts

When you asked about installing a new gasket you were advised that a new gasket would not solve the oil leak because the plastic covers warp and need to be replaced. Your home mechanic was correct when he said the bolts should be just snug. Tightening them further was not going to solve the issue.

You know the cover is warped because it still leaked with a new gasket. Your best course of action now is to install a new cover with new bolts. You will probably find the broken bolt is easily removed once the cover is off.

 

[Bhavick]

When you asked about installing a new gasket you were advised that a new gasket would not solve the oil leak because the plastic covers warp and need to be replaced. Your home mechanic was correct when he said the bolts should be just snug. Tightening them further was not going to solve the issue.

You know the cover is warped because it still leaked with a new gasket. Your best course of action now is to install a new cover with new bolts. You will probably find the broken bolt is easily removed once the cover is off.

How do you know the gasket is lsn’t leaking because the bolts weren’t torqued to 10NM as it says in the Haynes manual?

 

[Bhavick]

You do want to damage the bolt. That is the idea. Put a hole in it and in the process perhaps get an edge on it and it will be screwed out of the hole.
Look, this may not be a job that you will be comfortable with. This is what I would do given the task. It does take a bit of skill and and a sense of knowing when to stop and reassess the situation if things are not going well. You definitely do not want to break a drill or EZ-out tool in the end of the screw.
Left hand drill bits are usually not in stock at the typical home improvement stores. They are on line somewhere most often in sets.
Most battery powered hand drills these day are capable of being run in reverse.
You could use a regular right hand drill bit but it will probably run the broken bolt further down into the hole. And that is OK if you have the EZ-out tool to retrieve it once the hole is drilled. From the looks of it you might have to fashion an extension for the tool to clear the blocks and injector parts that are in the way.

Leaving the cover on will help prevent the shavings from falling into the engine. You just have to be careful not to damage the plastic cover. They are not cheap.

The Sealey extractor tool looks like it can handle the job of getting the bolt out. Failing that I’ll try left hand drill bits like you suggested. Can’t understand why darkside and Haynes both say 10nm but this home mechanic said it should just be snug tight. I don’t really trust the guy he seems like a fu*ckin c*unt after speaking to him. Maybe I should go and wrap a baseball bat around his head.

 

[pedroYUL]

10Nm is really no pressure at all. I have doubted that spec myself and almost broken the same bolts. Better to do those by hand using a 1/4" rachet, unless you have a torque 1/4 inch wrench, I don't.

 

[Bhavick]

10Nm is really no pressure at all. I have doubted that spec myself and almost broken the same bolts. Better to do those by hand using a 1/4" rachet, unless you have a torque 1/4 inch wrench, I don't.

So basically the Haynes manual is talking BS when they say torque to 10NM?

 

[P2B]

How do you know the gasket is leaking because the it wasn’t torqued upto 10NM as it says in the Haynes manual?

It probably WAS torqued to 10nm. That's very little torque, barely beyond snug.

The cover is plastic. They warp and leak. Very common. You can do the gasket if you like. Again and again, not my time. Knock yourself out.

@oilhammer is a well respected full time mechanic with decades of experience working on these cars. When he says changing just the gasket is a waste of time, I believe him. Your experience proves the point.

 

[Bhavick]

It probably WAS torqued to 10nm. That's very little torque, barely beyond snug.



@oilhammer is a well respected full time mechanic with decades of experience working on these cars. When he says changing just the gasket is a waste of time, I believe him. Your experience proves the point.

no when I asked the mechanic he said he didn’t torque it to 10nm that was the reason I was trying to retighten them in the hopes that it would fix the oil leak.

 

[JETaah]

As soon as the valve cover bolt head meets the spacer and the spacer meets the surface of the cylinder head, that is as compressed as the gasket will get regardless of how tight the bolt is. The spacer is there so that you don't overly crush the gasket. The 01m transmission pan gasket has spacers, coolant thermostat housings have metal spacers built in to the housing,...numerous applications for this method to establish the proper compressed dimension of the gasket.

10nm (or 7lb/ft) is just snug really.

 

[Bhavick]

It probably WAS torqued to 10nm. That's very little torque, barely beyond snug.



@oilhammer is a well respected full time mechanic with decades of experience working on these cars. When he says changing just the gasket is a waste of time, I believe him. Your experience proves the point.

I’m not denying his experience at all and it looks like that’s the route I’m going down anyway a complete genuine vag cover with new bolts and a gasket from dark side and left handed drill bits to try and drill out the snapped bolt. Looks like another £198 well spent not to mention the cost of a brand new alternator which was £125!

 

[Nuje]

Rocker cover = valve cover.

Ahhh - my British --> North American translator was apparently not working.

 

[P2B]

Looks like another £198 well spent not to mention the cost of a brand new alternator which was £125!

I'd be tempted to save 68 quid (+VAT) and go with the "OEM quality" cover Darkside sells - or at least ask if they've had any issues reported with them.

 

[Bhavick]

I'd be tempted to save 68 quid (+VAT) and go with the "OEM quality" cover Darkside sells - or at least ask if they've had any issues reported with them.

Yeah did consider that as they sell OEM and genuine vag ones but i think it's best just to go with an official one as I've had problems in the past fitting sensors and flanges from cheaper third party companies. Not to worry you live and learn i guess!