Uh oh, Front N/S Earth bolt broken off, advice for drill access please...

[Kennedy]

Hi guys. I've been having all kinds of trouble with the starter motor and alternator and inconsistent running/voltage etc on my 2004 tdi, finally tracked it down to the earth strap connecting behind the ABS unit (n/s behind headlight). The bolt was corroded and when I have tried to remove it it has sheared off, with very little force may I add.

In terms of drilling this out can anyone tell me if I'll likely get enough access with the bumper removed or if anyone has had similar issues? Is it easier to make a new earth point somewhere else?

A two minute job just turned into a few hours I fear!

Thanks for checking this out.
Kennedy.

 

[JIGSAW]

To get you on the road temporally until fixed id use the under tray 10mm chassie fixing point which is just under the earth point with a few washers for now but as its only 10mm, Id suggest searching the area for another suitable bolt to refit your earth strap, possibly holding the ABS pumps mounting bracket ect, as id imagine while trying to drill out the broken bolt you could damage the threads and being in such a location may be imposible to drill out straight and use a stud remover, especially as its snapped to corrosion it may be an imposible task, but any location on the chassie rail would be fine for a new earthing point, If youv got a mig welder handy, you could also try and weld a new bolt to the exposed thread thats left, so the bolt head is welded to the broken thread and use that to try and undo as once heated up by welding and then cooled it should brake the corrosion bond or even a couple of washers and then the earth cable and a new nut on the bolt youv welded on and fix that way instead, but remove the battery before welding if you chose that route.

Gary

 

[Birchall]

Hi guys. I've been having all kinds of trouble with the starter motor and alternator and inconsistent running/voltage etc on my 2004 tdi, finally tracked it down to the earth strap connecting behind the ABS unit (n/s behind headlight). The bolt was corroded and when I have tried to remove it it has sheared off, with very little force may I add.

In terms of drilling this out can anyone tell me if I'll likely get enough access with the bumper removed or if anyone has had similar issues? Is it easier to make a new earth point somewhere else?

A two minute job just turned into a few hours I fear!

Thanks for checking this out.
Kennedy.

Hi,

That frequently happens and I merely relocated the strap onto a bolt nearby as Gary said. you need to use one on the mounting bolts nearby. It has lasted a year so far!!!

Steve B

 

[Kennedy]

Cheers Gary, Steve, thanks for the advice. I changed my mind on drilling out the original, I think it would have been very difficult without dismantling the whole front end!

I looked around the same chassis rail and opted for the 13mm bolt on the underneath, apart from needing to remove a little of the join sealant it seemed like the best spot. The bolt on the left side was another possible but the brake lines limited space. I decided to flip the eath cable around too as the L-shaped end fitted to the car better than the straight end.

I'm all up and running again anyway, the starter is fine obviously, engine is now running smoother and not intermittently dropping revs and alternator is strong with a reading of about 15.6 volts at the battery terminals when running - previously this was all over the place and generally much weaker.

Thanks, Kennedy.