Im sick, lighning has struck twice and it ISNT amusing.....

[Sleeper_Avant]

dont know if you read but first time i used the car with the engine in i had timing belt tensioner failure due to previous owners incompitence, long story short it bent 10 inlet valves, done the cam pulley etc etc

allwere replaced with new VAG bits and today doing steady 30mph (genuinly) i slowed for a roundabout, dipped the clutch and it cut out, i tried to restart it but it locked up, turns out the wudruff part of the pulley had broken away, timing marks etc were all ligned up perfect and everything else is spot on, pulley has failed somehow!

to say im sick is an understatment as i had to spend £400 on bits alone for this less than 2 months ago or so.

no idea how pulley failed but everything else is perfect, will strip the cams out and check compression first thing monday morning :'(

oh and its my daily hack so am propper screwed!

Sean lol

[JP]

ouch not a happy puppy then! If it's the woodruff key on the cams then it means one of two things. Either someone has used an impact driver on it at one point or it was not torqued up properly with a fresh bolt. It's not the woodruff key that holds the pulley in place it is actually the friction of the head of the bolt to the pulley and pulley to the cam that stops it from spinning So torquing up is correctly is crucial, and a dab of loctite to prevent vibrational loosening doesn't go amiss for piece of mind. The woodruff is only a timing location pin.

If it is the lowr crank pulley same story as above.

[Acidburn]

Really sorry to hear this, i've heard of people having problems with the woodruff key before. I'll have to make sure mines done right when the time comes. Hope you get it sorted out asap.

[AndyP]

Did you use the Audi crank locking tool and the correct torque setting when you installed the bottom pulley?

[UrS4boy]

Sorry for your "loss" but yours is unfortunately NOT a unique story. It is not uncommon for the less than knowledgible mechanical (professional or amateur) to think that just because they have a BF Impact Wrench (related to the BFH, Big Fkn Hammer) that they should use it on the bolt that holds the crank end cam belt sprocket to the crank. The impact from removing or tightening this bolt can and has caused the integrally cast "key" in the sprocket to fracture. This can cause the cam belt to fail to function as required, the result being at least 2 bent intake valves, and in some cases, like yours 10 bent valves. Best to use the proper cranklock tools and a big snipe on the socket (probably best done with a 3/4" drive T-bar and socket)



The crank pulley PN is 034105263A (common to almost all the inline 5 Audi engines including the 3B, AAN, ABY and ADU) as shown here:



There are CNC machined billet steel pulleys out there in the market place. Still, the proper tools and methods for the cam belt replacement should be used.

Good luck.

[diesel des]

Ok I have to admit that I have used a 3/4 drive impact gun many times on these without problems. I don't really see how this gives a Problem. When you tighten a bolt some of that torque is used to tension the bolt, but most is used up in overcoming friction under the bolt head and on the threads. So if I were to lock the crank and use a pull bar the reaction torque is still putting stress on this key. How is more stress put on with a buzz gun? It's impacts are so fast that the crank and pulies inertia are not really overcome so there should be less stress on this key.

Where I'm I going wrong.

I always use a new bolt with loctite and empty my big buzz gun into it. I personally think the key is just a locator and the load is carried by the friction of the bolts head. The only way I can see the key brake is if the bolt is not tight enough and therefore the pullie slips on the crank as the key isn't strong enough to carry the torque.

Many new engines eg ford zetec etc have no key. Just relies on the tight bolt giving enough friction.

Just my opinion....

[gnutz2]

I agree with des, i cracked the key on my engine but luckily i spotted it as a misfire because i did run a vr sensor on the pulley (now moved to the crank).

This was my own fault for not tightening the bolt enough, IMO you cant use a 1/2 inch socket to tighten the bolt as there is way too much flex and it doesnd actually reach 450nm or 200nm + 180 deg.

3/4 or inch socket is the way forward, i think some garages dont realise actually how tight 450nm is, we have a big 3/4 torque wrench at work that we use for wagon wheels and this only goes to 400nm.

[Sleeper_Avant]

Cheers for the thaughts lads but it is CAMSHAFT pulley that has broken, no gun was used and as per conversation at santapod today JP, new bolt and torqued up, fook knows.

see if i can get it ready for bugjam! woohooo

[Gazjen]

You not supposed to use loctite Audi use a lubricant not a thread locker

And its the key and the taper that drive the cam not the friction of the head of the bolt on the pulley

The key is designed as both a locator and as a positive drive

you should change the timex pulley on the back of the crank pulley at every cam belt change and also check the woodruff key and key way dimensions on the cam pulley and cam

[jogi730]

Oh dear - I really can sympathise with you.
Hope you can get her sorted and soon.
Good luck
Chris

[Jamo]

Cam one is the same design as the crank,it is another know failure point, the pulley should be replaced when doing a cambelt service IMO as suggested quite a while back on the forum.

I'm using a Dahlback pulley and that removes said weakness

[GT500]

How did you hold the cam from turning when you tightend it?

[GazzaG60]

when i did my engine i went through 2 pulleys and was lucky it never damaged anything.

kid gloves. no leverage on the pulley and a thorough check of the cam one is always needed. a brand new one had signs of a breakage on the way,

like gt 500 says its how you hold it.

[s2_wot]

3/4" drive air gun with 6.5 BAR air supply can deliver 1300-1600 Nm easily. Check out www.cp.com for some figures. I'm also not sure about the locktite approach, the washer on the head of the bolt needs to be correctly lubricated at least.
HTH

[quattro]

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