Technical 2.3 JTD 2014 - snapped injector clamp bolts

[tomson]

I've snapped 2nd injector clamp bolt during injector removal. Luckily all 4 got out without much trouble after spraying rust removal fortnightly for past two weeks.

Bolt that snapped wasn't easy to unscrew just to start with, used ratchet, I was making one turn out, then half back in and slowly unscrewing. I was spraying it with WD-40, but it wasn't helping. I've went past the moment where I couldn't screw it back in without risking snapping, so I've tried to unscrew until it broke.

It seems that approximately 50% of the thread got out and remaining part is inside. The remaining part starts at 30mm depth.

It also seems that the bolt thread is partially damaged, so not entirely sure what's the condition of the thread that remains inside.

Any ideas, tips how to fix it?

a) I was thinking about using the broken bolt extractor to at least try get the remaining part out. Then check the condition of the thread / rethread, then if it's only partially damaged perhaps use some JB Weld or other magic.

b) Get some extractor tools, they're quite expensive though.

https://smart-go.pl/pl/p/Zestaw-do-urwanych-srub-wtryskiwacza-ducato-2.33.0,-zmiana-na-szpilke/898 - £150
https://smart-go.pl/pl/p/Zestaw-do-urwanych-srub-wtryskiwacza-ducato-2.33.0/852 - £1100


The one on the video for £500, assumes that bolt snapped outside.
I am not sure how effective/easy-to-use/reliable they're though.

I would either get the cheapest one or borrow one somewhere if possible.

c) Take the valve cover out and take it to some magician who can perhaps insert M10/M8 helicoil.
The challenge is that I am not a mechanic myself and taking the valve cover out means taking the shafts, out, chain belt, etc.
THe car is undrivable, I live in a remote place, so rather big towing costs.

d) Build a new clamp, longer than the existing one and use the valve cover bolt. Not sure how feasible is it and whether it would be possible to seal it properly.

Any help much appreciated, thanks!

 

[bugsymike]

Sounds like you are a bit "screwed";(
I wouldn't try the "building a new clamp arrangement " using the valve cover as there is a lot of pressure and the original design is what is needed.
Any chance you can employ a GOOD engineer to carefully drill out damaged parts and extract the remainder, or fit a thread insert/heli coil.
It needs to be done professional to ensure aligned and strong.
I say GOOD engineer as a poor one will end up costing you more by causing more damage.
There are some good parallel stud extractors by Rothenburg which I use, but a lot of care needs to be taken to keep the drill central etc. So a good engineer will save you money in the end.

 

[jackwhoo]

I think a stud extractor is a bad idea in this case. if the extractor snaps then there is no chance of drilling because the extractor metal is as hard as still bit material.

Drill out and fix with a thread insert.

 

[bugsymike]

I think a stud extractor is a bad idea in this case. if the extractor snaps then there is no chance of drilling because the extractor metal is as hard as still bit material.

Drill out and fix with a thread insert.

What ever route taken it needs to be by some one experienced, and if OP has already broken the bolt then not a lot of hope for a stud extractor if it is allowed to snap in hole.

 

[tomson]

Well, thanks for your help so far. Job is not easy.

Call me stupid or an amateur, but I am halfway through it, with some help of 10mm (outside diameter) bushes that helped me to centralize the drill.

I've initially drilled 4mm hole, then used 6mm drill, now I've got perfectly aligned 6mm hole in the snapped M8:

I plan to give it a go and use stud extractor (ordered some quality ones) with a light force and rethread existing M8.

If thread happen to be completely destroyed or stud extractor ineffective then I will go for M10 driling and use either helicoil or use double ended bolt.

I would normally order an engineer, as as you say don't have much experience with metal, but I live completely nowhere.

Will keep you posted.

 

[bugsymike]

Well, thanks for your help so far. Job is not easy.

Call me stupid or an amateur, but I am halfway through it, with some help of 10mm (outside diameter) bushes that helped me to centralize the drill.
View attachment 451227

I've initially drilled 4mm hole, then used 6mm drill, now I've got perfectly aligned 6mm hole in the snapped M8:
View attachment 451228

I plan to give it a go and use stud extractor (ordered some quality ones) with a light force and rethread existing M8.

If thread happen to be completely destroyed or stud extractor ineffective then I will go for M10 driling and use either helicoil or use double ended bolt.

I would normally order an engineer, as as you say don't have much experience with metal, but I live completely nowhere.

Will keep you posted.

You have to do what you have to do , I understand.
I have seen plenty of damaged threads on jobs even where so called professionals have been involved.
At least you are starting with the hole central, some don't even manage that.
As has been mentioned if you have to use extractors , be very careful as they are made of very very hard metal , so if you are unlucky enough to snap one in the hole it will be a major problem as drilling out is nearly impossible and 100 times worse than what you are faced with at present.

 

[jackwhoo]

Do not drill 10mm .

A m8 helicoil / vcoil type kit includes the correct oversize drill bit for the correct size thread cutting tap to use with the thread inserts. They are not standard sizes.

Keep in mind the bolt was stuck enough to break the bolt .....it is very likely to be so stuck as to break a stud extractor that will be much thinner than the original bolt.

You have a very good job at drilling .

Perhaps just go thread insert route.

Thread inserts in aluminium alloy are often stronger than original thread.

 

[tomson]

I've tried stud extractor, but as you've said things were stuck. Didn't want to risk breaking it. Tried to recover M8 thread, but that was unsuccessful. Aluminium is soft and brittle.

In the end I've bought the helicoil set with drill and thread cutting tap, but the coils weren't long enough to my taste, so I've ordered 20mm helicoil which pretty much covered the whole bolt.

The helicoil job was rather easy, I've had to buy the tap extension though, as the classic one wouldn't fit.

In a next few days I will be putting injectors back and hopefully things will work. Thanks for your help. The helicoil idea was fantastic!

 

[jackwhoo]

Hi,

Well done looks like a job well done.

It appears thread insert is at bottom of hole.One suggestion - when bolt and clamp fitted check the bolt goes into a reasonable length of the thread insert .
The bolt and clamp design probably probably leaves the bottom of the bolt several mm away from bottom of hole.

If you use thread inserts again you can fit the insert to a depth of your choice for maximum strength, the insert does not have to be screwed to bottom of hole, remember to snap the fitting tang off insert if bolt threads need to pass all the way through the insert.

Best wishes

Jack