Question on Stripped Serpentine Belt Tensioner Bolt...

smokedvw

Well-known member
Joined
Oct 6, 2005
Location
Victoria, BC Canada
TDI
2002 Jetta TDI Silver
Today while replacing my alternator I was putting the serpentine belt tensioner back on and stripped the thread which the longer bolt goes into... (the top one in this picture).:( I am assuming I am going to have to go with a helicoil kit to fix this. The bolt does not seem to come out on the other side to use a nut and it looks like a helicoil is the only way. We pulled out the windshield washer container and figured it might be to difficult to get a small drill in this area and may have to create a manual one with the kit and a socket set.

Is this going to be a problem to not fix this bolt and rely on the other 2 to hold the tensioner? It seems like this bolt takes more of the load for the tensioner.

I was looking for any suggestions from anyone who has had to fix this at this location before.

A hard pipe (I believe AC line) runs at the bottom of where the windshield wiper holder is and because of this its hard to get a drill at a level position with the hole that the bolt goes into. I have 2 small makita drills and the driver looks like it would be just small enough but the smaller drill hits the line and cant get level.


 

Joester

Vendor
Joined
Aug 17, 2009
Location
St. Louis
TDI
2002 Golf TDI
mine did the exact same thing when i was replacing the alternator. its been running fine on 2 bolts for about 5 months now, i forgot which one of mine stripped though.

I thought about it too, and i think a helicoil would be the only plausible solution.

I figure when it does break ill say "aww shucks" get AAA tot ow me home and Helicoil it. im kinda relying on luck to let it break someplace and some time convenient :D

EDIT: i think we actually stripped the same bolt. thats the one that part of the bolt shaft is smooth before the threads appear right?

if you do end up helicoiling it tell me how it goes.
 
Last edited:

wolfman79

Member
Joined
Oct 26, 2008
Location
Columbus/Gambier, Ohio
TDI
2002 Jetta
I just stripped the same bolt while installing my new tensioner! Has anyone checked to see how far the threaded hole extends into the engine block?...maybe a slightly longer bolt could be used to reach good threads?
 

Joester

Vendor
Joined
Aug 17, 2009
Location
St. Louis
TDI
2002 Golf TDI
IIRC the bolt goes all the way through, it actually doesnt go into the engine block i dont think, it goes in an aluminum part mounted to the engine block, but its such a giant part, you might as well just take out the engine to replace the part that bolt goes into.
 

VW Petrolero

Veteran Member
Joined
Aug 9, 2002
Location
Vancouver.BC
TDI
2018 Golf SW 1.8 TSI
Today while replacing my alternator I was putting the serpentine belt tensioner back on and stripped the thread which the longer bolt goes into... (the top one in this picture).:( I am assuming I am going to have to go with a helicoil kit to fix this. The bolt does not seem to come out on the other side to use a nut and it looks like a helicoil is the only way. We pulled out the windshield washer container and figured it might be to difficult to get a small drill in this area and may have to create a manual one with the kit and a socket set.

Is this going to be a problem to not fix this bolt and rely on the other 2 to hold the tensioner? It seems like this bolt takes more of the load for the tensioner.

I was looking for any suggestions from anyone who has had to fix this at this location before.

A hard pipe (I believe AC line) runs at the bottom of where the windshield wiper holder is and because of this its hard to get a drill at a level position with the hole that the bolt goes into. I have 2 small makita drills and the driver looks like it would be just small enough but the smaller drill hits the line and cant get level.


Just do the Helicoil repair and you 'll be OK THAT BOLT DOES MOST OF THE WORK IN KEEPING THE TENSIONER IN PLACE.
Later
 

mike92105

Well-known member
Joined
Apr 30, 2004
Location
Lemon Grove CA
TDI
2002 Jetta TDI automatic 2015 Passat SEL
I just did the same thing,stripped the longest bolt on the tensioner. At first I thought it was a helicoil that the factory put in because it came out looking like a helicoil. I've never done a helicoil so I guess this will be a new skill set for me. I thought about just drilling the hole all the way through as it appears the bracket is just aluminum, but figure I'll try the helicoil first and if that doesn't work I can always drill it all the way through. I'm pretty sure I never put more than 25 ft/llbs on the socket wrench. Still not sure why the factory didn't put more threads in there knowing it was aluminum and therefore not very strong.
 

DidJettarun

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Joined
Nov 16, 2008
Location
South Carolina
TDI
A5 2005.5 Jetta A4 2003 Jetta
Yep the bolt brings out the threads with it and it looks just like a failed helicoil...And yes when I did the repair I used two helicoils...one for the failed bolt and one for the good one that I drilled out by mistake talking to DanG144 while I was working...LOL
 

mike92105

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Joined
Apr 30, 2004
Location
Lemon Grove CA
TDI
2002 Jetta TDI automatic 2015 Passat SEL
Just finished, the bolt is a 8mm 1.25 pitch 3.25 inch long bolt. When doing a heli-coil you will need a 21/64 drill bit and an angle drill adapter. It was my first heli-coil so I took my time. Needless to say it took me a while, thought I busted out the tang, but on inspection with a mirror it was still there, several attempts later, gonzo! I was a little hesitant to put too much torque on it when I was done, does anybody know what the torque should be on this bolt?
 

mike92105

Well-known member
Joined
Apr 30, 2004
Location
Lemon Grove CA
TDI
2002 Jetta TDI automatic 2015 Passat SEL
The good news is the tensioner does not have to come out. You can drill and heli-coil right through it.
 

r72gsaol

Veteran Member
Joined
Jan 29, 2010
Location
Upstate New York (Have Vag-Com)
TDI
03 Jetta, 99 NB
Found this bolt missing on my beetle while doing the timing belt.

I just tapped it out to 3/8x16 SAE thread. The tap will go right into the existing hole with a little work and the hole in the tensioner needs to be opened up just a hair to 3/8.

Easy quick 30 minute fix.
 

brandonkraemer

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Joined
Dec 28, 2013
Location
Cincinnati, Ohio
TDI
2003 TDI 1.9L 5spd ALH VE mkIV Jetta Wagon
I've never attempted to tap out for a bolt before and I have this same issue on the long bolt for my tensioner. I like the sound of the tap vs. helicoil and doing the work with a wrench. Is there a pictorial on this type of repair or specific advice on necessary tools?
 

jimbote

Certified Volkswagen Nut
Joined
Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
Found this bolt missing on my beetle while doing the timing belt.

I just tapped it out to 3/8x16 SAE thread. The tap will go right into the existing hole with a little work and the hole in the tensioner needs to be opened up just a hair to 3/8.

Easy quick 30 minute fix.
this ^^.... easiest and quickest method! .... that one long bolt threads into a very thin part of tbe bracket ... it's no wonder it strips so easily
 

brandonkraemer

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Joined
Dec 28, 2013
Location
Cincinnati, Ohio
TDI
2003 TDI 1.9L 5spd ALH VE mkIV Jetta Wagon
this ^^.... easiest and quickest method! .... that one long bolt threads into a very thin part of tbe bracket ... it's no wonder it strips so easily
I just bought a GreatNeck 6pc tap wrench set. It has the 3/8" NC16 tap in the set... it was cheaper than the 3/8" x 16 Helicoil set the guy at AutoZone was recommending. I assume the only difference here is the coils themselves... that the taps are the same?

Does anyone know the bolt length off hand? I picked up a 3/8" -16 X 2.5" one but without starting the job and removing the old one I was guessing.
 

timsch

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Nov 12, 2009
Location
Brookside Village, Texas
TDI
2003 Mk4 Jetta (blue), 2003 Mk4 Jetta (black), 2011 Mk6 Jetta, all manuals
I just ran across this situation myself. It's too tight a space to use typical tapping wrenches. Any suggestions on how to best do this without buggering the hole? I've grabbed a tap before with a small vice-grip, which worked fine for that non-critical application, but with an engine I want to be as careful as possible about maintaining alignment of the tap.
 

Tdipwr11

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Joined
May 27, 2022
Location
Ontario
TDI
2003 ALH Jetta
Had a shop ruin one bolt, was a ***** to helicoil but it's possible lol Was holding on with 2 bolts as my harmonic balancer was holding on with 2/4 bolts but it's not ideal
 

mittzlepick

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Joined
Mar 18, 2001
Location
union maine
TDI
2004 jetta wagon (365k)2001 wagon tire burner 6spd 2003 wagon(417k)
I through drilled and used a carriage boltwith the square trimmed diwn
 

Tdipwr11

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Joined
May 27, 2022
Location
Ontario
TDI
2003 ALH Jetta
Be sure to cut the insert to the proper size before inserting after you tap and go slow. Use the brand name helicoil too. If you need to search the size of bolts and helicoil you need. Its out there
 

timsch

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Joined
Nov 12, 2009
Location
Brookside Village, Texas
TDI
2003 Mk4 Jetta (blue), 2003 Mk4 Jetta (black), 2011 Mk6 Jetta, all manuals
I am planning on tapping the existing hole to a 3/8-16 thread and getting a bolt to match as mentioned in post #12
 

Tdipwr11

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Joined
May 27, 2022
Location
Ontario
TDI
2003 ALH Jetta
Lots of option for repairs lol, I'll even add you can try using an original bolt with a paperclip inserted the stripped hole like I found mine to begin with haha
 

PakProtector

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Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
If going to the trouble to repair it, forget helicoil and skip right to TimeSert. This is not something you want to do twice... :) Secure the insert with 648 Loctite.

Douglas
 

timsch

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Joined
Nov 12, 2009
Location
Brookside Village, Texas
TDI
2003 Mk4 Jetta (blue), 2003 Mk4 Jetta (black), 2011 Mk6 Jetta, all manuals
I was able to tap the hole using an 11/32 12-pt socket on a 1/4" drive ratchet to hold the tap. There was plenty of room for that setup. I used WD-40 as the cutting fluid after seeing it recommended for aluminum tapping. Everything went well.

The thread length appears to be only about 1/2" before opening into a cavity, so I'll get a 2-1/2" bolt and just snug it up with a bit of threadlocker and call it good.
 
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