Cambelt tensioner stud failure - Known issue?

[VW_Boy]

Hi,

I recently had my timing belt replaced on my Jetta TDI (BKD Engine) and shortly after the vehicle broke down. It was towed into a workshop and they found a M8 stud that holds the tensioner on has snapped. The timing belt has let go and damaged the head.

Now I have looked online and there seems to be a known problem (small number of people however) with Jetta's and Passat's with the same engine type.

I know as the vehicle has done 210,000km and that it really has had three kits fitted including the factory one but the vehicle isn't that old. The stud should be designed to last longer shouldn't it?

On other forums they talk about either the stud snapping or pulling out of the alloy head. It sounds like the stud is normally larger but different on this particular model which causes the concern.

I don't want to pay for a new head but I don't think its the mechanics fault and it is also out of warranty.

Has anyone else had this or seen this happen?

I love the car but don't think I can repair it!

[jets]

Another early BKD has been reported some time ago on this forum, from memory at somewhere around 235,000km. with a fatigue crack from flexing leading to complete failure.
From what I have been able to find out, the 8mm stud was replaced with a 10mm sometime in 2006. The shape of the lower timing pulley was changed around the same time.
It's important on the early BKDs to change the stud at every cambelt change.

[nightphotographer]

Yeah it's a common fault and leaves both parties in a sticky situation, sucks for whoever carried out the service and it sucks for you. Bloody VW hey! Heard of a case here locally where it happened within a few weeks of the second belt being done (210k) on a BKD and VW Australia said they wouldn't help cover any of the costs. I think the repair bill was about $6k, which obviously is the used value of the car!

[VW_Boy]

"It's important on the early BKDs to change the stud at every cambelt change.[/QUOTE]"


Thanks for that information.

I just received an email back from a local VW Dealership. They told me Volkswagen's repair instructions do not mention replacing the stud but in the last few years the stud has been added to the parts kit where it wasn't prior. They said they would not replace the stud if the repair instructions say not too.

This is obviously very confusing. If I had purchased the kit to carry out the repair myself I would think I would use all the parts in there. In this case I am guessing Volkswagen actually don't want you to replace the stud??

[gldgti]

I wouldn't start thinking VW conspiracy here. Sorry for your issue though.

I have seen numerous types of stud used on the various TDI engines (I've owned and maintained many VW diesels), but this particular problem isn't unique to the BKD - and I'd go as far to say that its more of a "VW havent over engineered it enough' type problem. The torque spec of the tensioner nut is really high for the size of the stud. I am the kind of guy who uses a torque wrench for just about everything, but I have seldom torqued any of the VW 4 cylinder diesel timing belt tensioner nuts to the full spec - its just always felt way too much All it does is retain the tensioner and sure, you don't want it to undo, but I've seen it listed at 60Nm on one of my cars (forget which one) - just too high. I've never had one snap, and I've never lost a timing belt either, so I could be just lucky I suppose... but when you have serviced all your own (and families) cars for 15 years you do get a feel for what is right.

To the question of the repair - at best you will be up for new lifters and timing belt kit, head gasket and bolts, and at worst add to that cams and valves. Pretty massive job either way, but if you shop around you should be able to find parts for under $2k.

[Bora Sport]

It's a pity you are in Melbourne. I have a complete low mileage BKD engine and DSG gearbox that i want to sell.

[Snail Style]

Chuck me a vin mate and i'll see if i can pull up if it says on the workshop system that it needs to be replaced. I doubt they include it as part of the kit without needing to replace it, i always have replaced it for that reason.

[nightphotographer]

We used to replace the bolts when we did 105ks on these engines (vw dealer) they came as part of the kit so VWA are well aware of it.

[jets]

We used to replace the bolts when we did 105ks on these engines (vw dealer) they came as part of the kit so VWA are well aware of it.

VW were obviously well aware of a problem back in 2006, that's why they increased the dia. of the stud.

[jets]

I made a mistake in post#2, memory not so good. It should have read 383k instead of 235k. Here's the link, scroll down to post #19.

http://www.vwwatercooled.com/forums/f28/cambelt-change-interval-65388-2.html?highlight=ohammond

[jets]

Just came across some technical info from Continental [manufacturers of OE Contitech timing belts] re broken stud bolt on tension pulley.

http://aam-europe.contitech.de/pages/pic/media/montagetips/TN_12_029%20(EN).PDF

Another from INA, well known bearing manufacturer.

[dubster99]

Had a similar problem on the mrs 06 jetta, car lost power then stalled. Came up with cam senor. Stud didnt snap but bent so the tensioner came loose and lost time. Will be pulling off valve cover and have a look. M8 stud still and had the hole re-tapped and helicoiled. Fingers are crossed that I can retime and should be ok but read alot about the last week and Im thinking Ill be getting a second hand motor!

[Transporter]

As far as I remember the genuine kit comes with the studs in question, so it's hard to blame the manufacturer (Volkswagen), just because someone does the job incorrectly or DIY with the some dodgy eBay kit.