Former VWDieselParts.com Forum

Just thought I'd share this one

Get this, the timing belt tensioner stud on my 1.6 diesel started stripping. I managed to back it out and found helicoil threads on the stud. P.O. Helicoil fail! Aluminum threads ruined. WTF
New head? Machine shop? Another size helicoil? I couldn't find any info on an alternative fix, so I went and did something that is maybe not recommended - I don't know. E-Z Lok thread insert.

Had to disconnect everything and jack the motor up high enough to work, then carefully drilled it out - and I mean CAREFULLY. Drilling a straight hole by hand is next to impossible, right?
I got a set of bits and bored it out in 64th incriments. The only way I could figure out to drill straight was to hold a socket flat next to the bit (side, then top), then hold it "perfectly" still as I slowly pulled the trigger on my variable speed drill. The hole is only like 15mm max but it took a LONG time to do this. Any time I moved or took my eyes off it I had to recheck with the socket for straightness before drilling.

The the final size of the enlarged hole was 15/32"
Tapped it out to the required 9/16-12 and used one of these:
https://www.amazon.com/gp/product/B002W ... UTF8&psc=1
I did have to take it out grind a little off the insert because it wouldn't go quite flush but there was no way was messing with that tapped hole. I guess I got about 12mm of threads out of it. Plenty of red loktite on the insert.
Screwed in the stud and it checked out straight with the socket held flat next to it.
It holds. No turning back now...

outstanding. I have never personally used one of the ez lok inserts but have heard they work well if all the hole prep is good and you use threadlocker, etc. I have used something similar on stripped spark plug holes with 100% long term success so you're probably good to go.

I put extra threadlocker (red) on the insert. Tiny amount of anti-sieze for the stud.

My pick up had that same hole threaded. I think its the combination of the aluminum and the terror of the tensioner slipping.

In my case there were a few threads beyond what was stripped so i got a longer bolt and used removable threadlock.... then drove with slight anxiety for the rest of the vehicle's life. You clearly win. Nice drilling

After searching the web for a while, I got the idea from this funny vid https://www.youtube.com/watch?v=YIAK7sB4YIg
"there's ways to do things the right way, that are wrong..." (laugh) ?. Plenty of better videos out there but that one got me started on finding a practical insert.

With some careful shopping, it was the same cost as a helicoil kit but much better. I got 10 inserts, the tap, and a good 15/32" bit from Amazon, then a 29 piece bit set from HF.

Figuring out how to drill the hole sure was the hardest part. I went through ideas like (or while) rummaging through trash. Fortunately I could hold the drill still with one hand resting on the top of the fender. The flat area next to the stud hole is enough to check a good size deep-well socket up flat against the drill bit in the 9 and 12 o'clock positions with the other hand.

A perfect cut piece of angle iron ,to eyeball it, and having extra hands would be a better, faster way to do it.
And if the head is ever off, it might be worth getting that stud hole upgraded so these problems don't happen.