Disastrous Clatter From VR6 - tensioner bolt causes rebuild!

[dr_mat 0]

Don't forget the intermediate cog on the timing chains, and the attached oil pump drive gear. That wears and clatters on old VR6s too ...

[barrowfordred 0]

The more I read of this, the more it puts me off buying a VR6 engined anything.

[Kevin Bacon 5]

I hate to say it, but the advice we give on here about visually inspecting the upper tensioner pad being the ONLY way to know for sure, goes largely ignored and is sometimes poo-pooed by the "Mine's fine, it's quiet" crowd.

 

Well, this, I'm afraid, is once again proof that a quiet VR6 isn't necessarily a healthy one. Call it scare mongery if you like, I call it preparation for a bill that if done soon enough, will be a smaller bill than it could otherwise be.

 

The only way to fix this permanently is to remove the original upper tensioner pad and fit the later MK4 one. VW redesigned this pad 7 times, so that must suggest something :wink:

 

Incidentally, "Dropping valves" isn't something that happens on VR6s. That is the 1.8T's party trick with it's 2 piece valves, but isn't common. The VR6's are one piece and the only way to 'drop' it is to physically detach the collets. And the only way that would happen in service is if a valve spring snaps....and that is rarer than rare thing being rare on St Rare's day....

 

8 valves clouting pistons is most definitely a result of the cams slipping round more than 2 teeth....

[dr_mat 0]

It's the fine line between constant paranoia and blithe ignorance resulting in destitution!

All engines have silent failure modes, the VR6 isn't alone in this ...

[dukest 0]

The more I read of this, the more it puts me off buying a VR6 engined anything.

The unfortunate lesson learned is that of the list of preventative things that can be done to see how the engine's looking, some are more involved than others - eg. what Kev outlines above. So, if doing major work on any part of the car, you should take the opportunity to look at anything else that is easier to look at while you're doing that other work than it normally is.

 

That this has happened to a VR is something anyone who even considers buying one would make themselves aware of as a possiblity beforehand. Its the single most well known thing about buying a VR, even for people that have never bought them. What it isnt by any stretch is a reason to not buy one, its a reason to ask, as 98% of people do, "have the chains been done?".

 

On a separate note, just because this is so unfortunate, if it had happened to me there would be something in the back of my mind questioning whether everything went back together alright after the gearbox had been off..

But I dont know anything about who did the work and am not casting aspersions anywhere without knowing any of the background.

[Kevin Bacon 5]

All engines have silent failure modes, the VR6 isn't alone in this ...

 

Exactly! Rubber timing belts certainly don't give you any audible warning they're about to snap!

[andy 0]

if it had happened to me there would be something in the back of my mind questioning whether everything went back together alright after the gearbox had been off...

I wondered if anyone else would question that, the VR6 is in my experiences, one of the toughest, robustly designed engines around.

[barrowfordred 0]

if it had happened to me there would be something in the back of my mind questioning whether everything went back together alright after the gearbox had been off...

I wondered if anyone else would question that, the VR6 is in my experiences, one of the toughest, robustly designed engines around.

But not when the timing chain goes. Which seems to be the case.

[dukest 0]

if it had happened to me there would be something in the back of my mind questioning whether everything went back together alright after the gearbox had been off...

I wondered if anyone else would question that, the VR6 is in my experiences, one of the toughest, robustly designed engines around.

But not when the timing chain goes. Which seems to be the case.

i dont follow you. which engine are you saying is robustly designed after the timing belt or chain goes? if the timing belt or chain goes on any car then the engine is scrap.

 

given that this is possibly the 2nd occurence of this that I've seen in 5 years of being on this forum I think its safe to say its very rare and also avoidable. no-one complains about timing-belt engines going bang at 80k miles if the change interval is every 50k and someone just hasnt bothered to do it.. these engines regularly do twice that without changing the chains/guides/tensioner but if you go beyond 80-100k without checking them then you run a risk.

[fla 9]

The more I read of this, the more it puts me off buying a VR6 engined anything.

Perhaps the VR6 is just not for you then? There are other options, best to stick with one you're more comfortable with.

 

However, as mentioned above, it is a very strong engine indeed - i've seen timing belts go on more than one occasion and heard of chains going in supposedly super-reliable cars, so its not a VR6 issue per se, its something that can happen to any chain, any belt, in any car.

[barrowfordred 0]

i dont follow you. which engine are you saying is robustly designed after the timing belt or chain goes? if the timing belt or chain goes on any car then the engine is scrap.

That is what I mean. Doesn't matter how robust the engine is, if the timing chain goes then you have problems. The problem here has been wear to the timing chain assy. And so, despite the robustness of the engine as a whole, the weak point, in this instance, was the timing chain.

[Toad 0]

i dont follow you. which engine are you saying is robustly designed after the timing belt or chain goes? if the timing belt or chain goes on any car then the engine is scrap.

That is what I mean. Doesn't matter how robust the engine is, if the timing chain goes then you have problems. The problem here has been wear to the timing chain assy. And so, despite the robustness of the engine as a whole, the weak point, in this instance, was the timing chain.

 

But it is well documented, and with a sensible inspection regime, or replacement for piece of mind, you are cutting the risks down dramatically.

[dukest 0]

i dont follow you. which engine are you saying is robustly designed after the timing belt or chain goes? if the timing belt or chain goes on any car then the engine is scrap.

That is what I mean. Doesn't matter how robust the engine is, if the timing chain goes then you have problems. The problem here has been wear to the timing chain assy. And so, despite the robustness of the engine as a whole, the weak point, in this instance, was the timing chain.

so why is it putting you off buying a VR6 when it is the same for every engine in the world..??

[Kevin Bacon 5]

LOL....here we go again :lol:

 

Barrowfordred has a valid point. Firstly with the chain gear not being particularly great and secondly that the VR6 is not that strong.

 

We are not talking about a 'normal' engine here. Due to it's unique design, it is incredibly easy to over heat. Why else do you think VW fitted a huge radiator, gave it 12 litres of coolant and fitted a 3 speed fan setup? Good cooling is absolutely essential for this engine and is why we have a massive thread dedicated to just that!

 

If an average 4 cyl engine overheats and pops the gasket, you just replace it and move on. If a VR6 overheats and pops the gasket, there is a good chance a bore (or two if you're unlucky) will get scratched. Why? Because aside from the shear heat of 6 cylinders operating so closely together, the water jackets around cyls 1 and 6 aren't as big as 2,3,4 &5. It's no coincidence bores 1 and 6 wear prematurely. Not always to a massive extent, but they *DO* wear quicker than the other 4. It's a well documented fact.

 

So whilst I agree the VR6 is 'physically' strong, it doesn't wear well. Compare it to the 24V (which underwent significant improvement), to the 1.8T, to the FSI engines, to the 8 and 16Vs. None of them wear out as quickly as the 12V, comparatively speaking.

 

Those of us who have been to Stealth have seen with our own eyes how many shagged VR6 engines they have lying around and last time I spoke to Vince about it, they rebuild 3 or 4 a month (to standard spec), and that's just one workshop in one country.

 

Just because someone is rightly questioning the VR6's strength, we shouldn't be quashing his thoughts with unsubstantiated nonsense about VR6s being bomb proof.

[dukest 0]

Kev, I was only questioning his suggestion not to buy a VR because the engine gets f*cked if the chain set up fails - every engine is f*cked if its belt/chain setup goes!

 

And so, despite the robustness of the engine as a whole, the weak point, in this instance, was the timing chain.[/b]

This just doesnt support the argument because everyone knows belts and chains can go, but if you observe belt change intervals or make preventative maintenance checks as you (Kev) described earlier in the thread then it is to all intents and purposes avoided.

 

Personally I wasnt saying the engine is any better than another, just that there is no reason to avoid it just because it has the same ability to fail that any engine does if you dont maintain it properly.

[4eyes2wheels 0]

So what is the manufacturers recommended chain replacement interval?

 

Had my chains done at 74k because the gearbox was out for repair and it was "daft not to do them", and the clutch while we're there and a few other bits and bobs.

[h6 vwc 0]

Not all engines are scrap if timing belt/chain snaps....depends whether its an interference engine or nt.

[davidwort 0]

Not all engines are scrap if timing belt/chain snaps....depends whether its an interference engine or nt.

:) get yourself an 8v 2L corrado... now if only it wasn't digifant :bad-words:

[andy 0]

Nobody knows if the weak point here was the chain. If a tensioner bolt had failed, it could easily cause the chain to slip. Was it fitted correctly, what's its history? So many possibilities. Sorry to bring it up again, but I know of many VR6s that have lived long hard lives, mine included with 150k miles. It pulls like a train, runs smoothly and has never been apart. That's pretty robust in my view. I know the lump has its weaknesses, as Kev mentioned cooling, however with proper maintenance you can minimise the risks. I seriously think my VR6 has done more work reliably than any other car I've owned or even know of.

[Kevin Bacon 5]

/\ Agreed, which is why I mentioned the tensioner bolt originally.

 

In more detail.... If you were to remove the rocker cover, drain the tensioner bolt and refit it again (as if to replicate fitting a new one from VW, or one that's failed), the amount of slack between the 2 cams is unbelievable. I've observed that it takes a good 15-20 seconds of cranking (with no plugs in) to repressurise the bolt. A misfire during this critical pressurising stage can be disastrous if the kickback causes one, or both of the sprockets to jump 2 or more teeth.

 

As for it happening so soon after removing the gearbox. I think it's just a coincidence. The lower chain and sprockets are covered, so you would either need to drop something down the side plate gap to jam in the sprockets, or deliberately sabotage the upper, exposed chaingear. I know some shady garages do dodgy things to get repeat business, but that would be extremely low!

 

I think if anything, the garage could have checked the state of the upper tensioner and warned the customer....but if the garage doesn't know the engine, he was probably none the wiser.

 

Anyway, I think the OP can notch it down to experience and move on. If it were me I would source a decent 2.8 24V, or an AAA OBD2 from a Highline. May aswell take the oppurtunity to make some improvments!

[vornwend 0]

Pretty sure Vince @ Stealth would have checked mine when he put new cams in last year (wish I'd remembered to specifically ask) but will get it checked again next year for additional peace of mind.

[Kevin Bacon 5]

Yep, Stealth do check the tensioner. Mine went in for a head rebuild at 93K and was told the tensioner was down to the rivets!!

[Erny 0]

Also if considering lookin for another engine to simply swap don't ignore the automatics that are offten for sale, I've notice they don't seem to sell as fast and don't fetch as much money, and seen as you already have everything it's just a case of whipping the flywheel n clutch of yours and putting it on, ied imagine you could pick one up for around 300quid. There often not gunna have been ragged to death like most manuals

[MikLSP 0]

Thanks for all the comments lol!

 

The timing chains were something I knew were a weak point but if I'm honest I perhaps thought things were are little exaggerated with paranoia and doom sayers. When buying a Corrado the chain rattle was a main concern but I (know I realise wrongly) thought that there being no noise meant things were not in imminent danger.

 

As for the recommended service interval, I believe there is none as VW originally (also wrongly) envisaged the chains and tensioners to last the lifetime of the engine :cuckoo:

 

I'm not going to start pointing fingers at Ady the mechanic who did my gearbox & clutch as I wouldn't have thought he touched anything down there which has caused this...

 

As Kev says, this is one I have to put down to experience and bad luck. I just have to bite the bullet and at least be glad that after all is said and done I end up with an engine which I can fully trust. It also makes me want to take the car to a better level in the future, the bodywork is "ok" at the moment but I think once I get a mechanically sound beast I'll be tempted to get that up to scratch too ;) (later that is) :lol:

[MikLSP 0]

Can anyone confirm that this is a list of all I need to replace everything on the timing chains? Cheers :)

Is there anything I have missed?

 

Upper timing chain

Upper timing chain guide rail

Upper timing chain tensioner rail

Upper timing chain tensioner bolt

Lower timing chain

Lower timing chain guide rail

Lower timing chain tensioner rail