Rethreading Kit

[AnneR]

Hi, I am trying to find a specialist kit but have no idea what I am looking for...

Please let me explain. I had a mobile mechanic come last thursday to fit a new washer in the injector? (sorry I am not mechanically minded). Anyway, he left thursday saying he needs to order a specialist kit so he can re thread the head so he can refit the injector. That was a week ago and he still has not been back. I am unable to use the car and I live in a very rural area so this is very frustating for me.
So, please, can anyone tell me the name of this kit I need so I can try and track one down?
Any help would be gratefully appreciated,
Kind regards
Anne

 

[Jonesy161]

Try googling Helicoil, this is what I used to use in engineering, not sure if it's the same thing as your mechanic needs. Hope it helps.

 

[Giantvanman]

When something has external threads (like a bolt) or internal threads (like a nut the bolt screws into), the threads on either can become damaged. One way to repair threads if they are damaged is to use a tap and die set (die for external, tap for internal). This tool recuts the threads BUT if the damage is too severe on internal threads, sometimes something called a Helicoil is used. This looks like a small, tightly wound spring that goes into the 'hole' to provide a replacement/substitute screw thread.

To slightly complicate matters, the correct tap has to be used…the correct length and pitch for the screw and that might be what is taking the time. Have you phoned him to see what the hold up is? This tool is not specific to Mercedes and can be bought fairly easily at engineering supply shops.

 

[KennyN]

If you are not familiar with threading metal then it will not be a job for a first timer.

It may be more economical to call a mobile repairer to complete the job as it sounds like the original guy made an **** of something , hence him not returning and it would be doubtful if you will ever use the kit again and ,for a decent set , it wont be cheap.

Kenny

 

[AnneR]

Try googling Helicoil, this is what I used to use in engineering, not sure if it's the same thing as your mechanic needs. Hope it helps.

Thank you so much for your quick reply and help.

That helicoil looks like what I might need but I don't know what size?

I have a Mercedes ML270 what this information be in the handbook and what would it be under?

Again, I am sorry but I have no car savvy :fail
Kind regards
Anne

 

[AnneR]

To slightly complicate matters, the correct tap has to be used…the correct length and pitch for the screw and that might be what is taking the time. Have you phoned him to see what the hold up is? This tool is not specific to Mercedes and can be bought fairly easily at engineering supply shops.

I have contacted him twice but he said it has still not arrived.

Would you know what size I would need for a Mercedes ML270? If I could by the parts I need I could then try and find another mechanic to fix it for me.

Kind regards
Anne

 

[KennyN]

If I could by the parts I need I could then try and find another mechanic to fix it for me.

Any reputable mechanic will have a "helicoil" kit plus they may not guarantee the work if it was repaired with a part supplied by yourself.

Kenny

 

[Giantvanman]

I have contacted him twice but he said it has still not arrived.

Would you know what size I would need for a Mercedes ML270? If I could by the parts I need I could then try and find another mechanic to fix it for me.

Kind regards
Anne

The Helicoil normally comes as a kit in a small tray. I cannot say what size you would need because that would depend on what damage has to be repaired. The internal diameter will be the same as your plug but the external will depend on what has to be removed….hopefully someone will be along who has done this but I wouldn't rush out and get the kit (they are not cheap) with the intent of using it for two reasons; it requires some skill and experience to do it correctly without damaging the head further and as mentioned before, any mechanic worth his/her salt will have a kit on their toolbox. They would charge a few pounds for one but a whole kit would cost considerably more and the rest will be of little use to you.

When you find another mechanic, explain the issue, mention Helicoil, and they will likely have a set or get one to use if they are running low.

EDIT: It is only my opinion but if it were my car, I would prefer the hole be TIG welded and a new, correct size hole made for the plug. Im my opinion, this is the better engineering practice and although the Helicoil can and does work, it lacks engineering elegance...

 

[Chrishazle]

How do you re-thread the head without getting swarf into the cylinder? If the job is being done without removing the head, I'd be concerned about that!

I'm no mechanic, so may be talking rubbush (not unusual!!).

 

[AnneR]

Thank you so much everyone for all your help. I really do appreciate it.

I am still open to any comments that you feel may help,

Kind regards
Anne

 

[KennyN]

How do you re-thread the head without getting swarf into the cylinder?.

I believe the injector is held in place with a screw that goes through a spigot / flange at the side of the injector (and into a blind hole on the head) and not like a spark plug whose thread is directly into the bore.

Kenny

 

[AnneR]

An update:
I have heard back from the mechanic and he said he is waiting for a time-sert? He said it is now in and will be here on Monday.
Kind regards
Anne

 

[toolman1954]

Hi,
From what you have described it would seem that the retaining bolt for the injector clamp has stripped its thread and now requires a repair.
Here is an excellent "" How to do it " from member " E270. " Just some light reading for you, so that you may enter into some meaningful discussion when the mechanic re-appears to repair your vehicle. He may well be surprised at your knowledge of the subject matter !

http://www.mbclub.co.uk/forums/engine/169126-cdi-injector-bolt-repair-time-sert.html

 

[ronnieboy]

sound like the kit he is waiting for, as long as he knows what he is doing it should be a good repair.