Actual TDI Balance Chain Failures?

Rusty911

Rusty911

A2OC Donor
I've read about the potential failure of the TDI balance shaft / oil pump assembly (chain / tensioner / sprocket wear): is this on the 75's or just the 90's? And how many people have actually suffered it first hand: i.e. on your own car? This being distinct from hearing about it, mates of mates, blokes in pubs etc.

Of those (if any) have any written the engine off? Or is it a case of fish out all the dead bits, fit new parts and off we go again? I have read the post on Sarge's thread re: complications of reaching bolts etc. Frankly if the gearbox came off, a six speed would probably go on anyway so that's not a huge loss.

Clearly if you've got an immaculate TD90 Sport with all the options, you'll probably be looking for every insurance policy against failure. My 75 is at the lower end of the value spectrum it must be said, so trying to gauge the real risks here: 1 in 10,000, 1000, 100 or ... 2! Was I lucky to nurse to and from the MOT, or if it goes in next 175K miles (on top of the first batch of 175) I've been unlucky?

Engine shows every sign of being very healthy: starts on first compression, runs uber clean.

Many thanks :)
 
I can't shed any advice or information on this personally, and in fact am equally interested to hear valid answers.

One thing that I would like to add though, call it advice if you like as I believe you are relatively new to the A2 but please don't think that the TDI 75 is any lesser or inferior to the TDI 90 as it has a little less horsepower, as from reading some of your posts I get the impression that you have the 90 on a bit of a pedestal as perhaps the 'ultimate A2'?

Having owned a couple of 90's in the past and countless 75's, I for one (and I don't think I'm alone) much prefer the 75 over the 90 and in fact would only own the 75.

My reasoning for this?...Personally, I prefer the more simplicity of it, the lack of the variable vane turbo and dual mass clutch, both of which can be problematic (I had limp mode issues on both my 90's which I've never had on a 75) and can be difficult to get to the bottom of and costly to replace if needed.

Not to mention the far better fuel economy that you get from the 75, which from my experience can be as much as 10-15 mpg.

I don't mean to be negative to the 90 or attempt to put you off as other's absolutely love them but in my opinion a 90 is not more desirable or worth any more than a 75.

Finding a looked after well maintained example is always key for me.

One thing I do prefer and wish the 75 also had is the rear discs that the 90 has.

All the best and keep up the good work ?
 
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My car had done 280,000 when i changed the chain, it was very worn the tensioner had all but worn away, the engine is much smoother now
 
A2Z said:
I can't shed any advice or information on this personally, and in fact am equally interested to hear valid answers.

One thing that I would like to add though, call it advice if you like as I believe you are relatively new to the A2 but please don't think that the TDI 75 is any lesser or inferior to the TDI 90 as it has a little less horsepower, as from reading some of your posts I get the impression that you have the 90 on a bit of a pedestal as perhaps the 'ultimate A2'?

Having owned a couple of 90's in the past and countless 75's, I for one (and I don't think I'm alone) much prefer the 75 over the 90 and in fact would only own the 75.

My reasoning for this?...Personally, I prefer the more simplicity of it, the lack of the variable vane turbo and dual mass clutch, both of which can be problematic (I had limp mode issues on both my 90's which I've never had on a 75) and can be difficult to get to the bottom of and costly to replace if needed.

Not to mention the far better fuel economy that you get from the 75, which from my experience can be as much as 10-15 mpg.

I don't mean to be negative to the 90 or attempt to put you off as other's absolutely love them but in my opinion a 90 is not more desirable or worth any more than a 75.

Finding a looked after well maintained example is always key for me.

One thing I do prefer and wish the 75 also had is the rear discs that the 90 has.

All the best and keep up the good work ?
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Thank you for all :)

Just to clarify, I wasn't suggesting the 75 was inferior to the 90 or visa versa. Like you, I very much appreciate the relative simplicity and reliability of the 75. Indeed, I do short journey's for much of the time so had pretty much ruled out 90's due to their VNT's. As the long term owner of a Passat 130PD I'm very familiar with the grumpy way VNT's approach long term short trips! DMF's are not the end of the world, but again, if a car was designed to run without one, happy days: I'll do without the tiny gains in NVH and possible transmission wear if remapped.

I definitely agree that the condition of the thing is by far the most important thing. Even so, for me and my needs, if it's a diesel, the 75 reigns supreme. I didn't realise the economy was so different either, although again, my Passat is markedly less economical than my neighbour's pre-PD 1.9 so I shouldn't be surprised. Economy = very, very good in my book ?

No, I was simply alluding to the fact that the 90's were the most expensive when new and appear to command a premium still now, all else being equal. Someone who has just bought an A2 for, say, £3000 is much more likely to spend a further £3-400 defusing a potential problem than someone running an older, perhaps less expensive car where that same sum might be 50% of the car's value. The latter may choose to throw the dice and take a chance and it's that element of risk I'm looking to assess.
 
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steveb said:
My car had done 280,000 when i changed the chain, it was very worn the tensioner had all but worn away, the engine is much smoother now
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Thank you. Interesting ? Could take that both ways I guess: i) tensioner wear is a real thing and will lead to issues in the end, or ii) despite 280,000 miles and a worn tensioner, the chain still hadn't snapped. Could you hear it at all? I know the V6 diesels rattle on cold start when the chain is loose, but that's a hydraulic tensioner I believe (coupled with worn plastic guides).

I'm in the midst of doing the timing belt (lack of support beam has stopped play until I make one tomorrow evening): I wonder how much more stripping would need doing in order to inspect the balance drive assembly? The alternative I guess is to go in with my mechanic's stethoscope and have a listen to the area. Engine seems pretty smooth to me on the one drive I've done with it.
 
If you are there anyway , not much more to drop the sump and check
We have replaced chains due to failure and preventative maintenance, the latter is preferred
The tensioner is oil pressure assisted thru a pinhole with spring force in the piston
 
It's not difficult to get to the chain, sump, crank bolt chain casing etc to remove, you will need a new oil seal and a means of refitting it as it's not a "normal" oil seal. Before i changed it, you can see in the pic. how far the tensioner is out
A2 timing chain.jpg
 
Oh, I see!

Would it be fair to suggest there would be some sort of noise coming from there if things were very worn?

Of course, under the current situation getting parts isn't a given (and I wouldn't want to put a strain on any delivery system anyway), so I'm a bit reluctant to dive in only to find I've disabled the car for the foreseeable future for something that turned out to be fine. On the other hand, if I thought it was about to let go for some reason, the point would be moot: it wouldn't be usable anyway.

Just to reiterate, it runs smoothly, quietly and starts on first compression suggesting minimal bore wear. It has 175K on it and I was told has been serviced annually, although the book is pretty patchy.

Tell me, that's surely not a counter weight at the four-o-clock position? If so, does the photo make it look bigger than it is? I get the impression it's about six inches across ...

Ooh, '79 Scirocco Storm: what I would have given to upgrade my 79GLS to a Storm back in the day :cool:
 
Balancer failures reported here -

Saving an ATL 90 with a broken balancer chain - part 1/3

Some of you may remember that I posted a request for help in June 2017 for a 2005 TDi 90 that had decided to throw a balancer chain... Well there's a long story (with a happy ending) that I thought I'd document. Starting with the suggestion to drop the engine through the front on a warm sunny...
www.a2oc.net

Information - Sarge's A2 Servicing Information

21 Removing Interior Heater Fan Motor Fault: No heater fan motor action, the fan speed indication on the climate control may show increasing bars then drop down to one bar but fan doesn't work. This usually is the fault with the heater fan motor and to replace it is as below. Disconnect car's...
www.a2oc.net

Cheers /spike
 
spike said:
Balancer failures reported here -

Saving an ATL 90 with a broken balancer chain - part 1/3

Some of you may remember that I posted a request for help in June 2017 for a 2005 TDi 90 that had decided to throw a balancer chain... Well there's a long story (with a happy ending) that I thought I'd document. Starting with the suggestion to drop the engine through the front on a warm sunny...
www.a2oc.net

Information - Sarge's A2 Servicing Information

21 Removing Interior Heater Fan Motor Fault: No heater fan motor action, the fan speed indication on the climate control may show increasing bars then drop down to one bar but fan doesn't work. This usually is the fault with the heater fan motor and to replace it is as below. Disconnect car's...
www.a2oc.net

Cheers /spike
Click to expand...

Thanks: caught the second (hence the thread) missed the first!
 
steveb said:
Yes it is a balancer, which helps the chain to wear. Mine made no noise at all.
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Ahh, I'd misunderstood what I was looking at. I had assumed there were twin balance shafts (outboard) with a central shaft to drive the pump. I can see the chain assembly is doing quite a bit of work.
 
I was getting the timing belt done at 195k miles and decided to have the oil chain done too. The only complication was the MYP 6 speed box made getting to the two sump nuts near the flywheel end trickier. I've owned the car since it had 40k and its been serviced every 9 or 10k miles with VW spec oil. The oil chain Tensioner was quite worn and the chain was wearing a little grove in the block. Gears weren't bad but changed anyway. As mentioned though its not huge money to do this if getting the timing belt done as long as you gather the parts from ebay!
 
Yup had Weetank's cousin do the work on mine at the end of 2018 with the car on around 145k.

Again the wear wasn't great and in time it would have failed. Its a one time only job as far as I'm concerned as if the car gets to 300k I'd be very surprised :)
 
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bretti_kivi said:
there's more reports of changes and when they happened here https://a2-freun.de/forum/forums/topic/40031-die-ölpumpenkette-eine-statistik/ (though you may need a google translate, depending on your language competence).

- Bret
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Thank you for all the replies. I've just had a look through that thread, thank you. Lots of large mile (kilometer) numbers, ramp wear etc but no pictures of actual catastrophic failures (although they might be described admittedly).

I think I'm going to put my 'Mr Pragmatic' hat on: 1) start it whilst in the air and part stripped and have a listen with stethoscope . 2) If it sounds horrible or, upon dropping oil I see any evidence of slider bits (on most cars, as they wear the outsides of the 'ridges' start to break off) I'll change it all out now. 3) If it sounds fine and the oil looks O.K. and knowing that the engine feels pretty smooth to me, I'll try the car for a while.

If I could access the area without risking the oil seal, I'd strip it, but as it is, I think it's a case of, for now, if there's no evidence of problems (as opposed to expected wear) I'll leave well alone. I really don't want to disable the car only to find it was actually OK anyway.

If I love the car and it turns into a keeper (entirely possible), once the current lock-down is past and all of my suppliers are back up and running I'll treat it to the full kit. In the meantime, assuming it passes the above tests I'll just keep an ear out for any changes in noise or engine NVH.

As I pay zero for my labour and I have a garage to work in, it's no great hassle to strip the timing belt area back out again later. Indeed, since for now I'm only doing a bare belt, if I commit fully to the car I'd be fitting a full kit later anyway (it had a full kit six years but only 15K miles ago, hence belt-only for now).

Many thanks again :)
 
Quick query: I'm in the midst of doing the timing belt (now I've made an engine support beam).

If I was to drop the sump only, would I be able to see enough to make any sort of assessment on chain / tensioner ramp wear? Or ... if I pull the front cover off as well, does that destroy the seal or can it go back on again?

Do I need any gaskets or is it all RTV sealant (of which I have some Loctite / Porsche sump RTV that would be fine I'm sure.

Finally, the sump 'bolts' appear to have both external and internal hexes. Is the internal for factory assembly and the external for maintenance, or is there some lovechild tool as a product of a liaison between a hunky 12 sided socket and a slender yet shapely allen key?
 
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