VW 97 Pasat Tdi belt Problems - BB
Hello everyone,
Hope you are all well.

Recently (2500 miles ago), I had a cam belt jump a tooth due to a failure of the alternator belt. Remains of the alternator belt was the cause of the cam belt to jump. This was then fixed by VW -no engine damage.

On the way to work this morning, I had a sudden loss of power and the alternator light lit up on my dashboard display along with a loss of power steering (as the alternator belt also drives the power steering.) I pulled over to the hard shoulder and switched the engine off. I looked under the bonnet, the alternator belt was still intact. After a couple of minutes, I tried to restart, but it wouldn't. .

I have now taken the car back to the VW garage where the tensioner and Cam belt were replaced to see what the problem is. I am unsure as to whether the cam belt has jumped again or snapped, but have any back roomers got any ideas as to what the problem is?

The loss of power was identical to when the cam belt jumped last time, but I can't understand why the alternator light lit up on the dashboard unless it is a faulty alternator, or I have had something seize on me in that area (water pump?!?) The RAC chap who came to see me thought that it was a cam belt issue.

How could the cam belt jump? I have still got the cam belt under guarantee, so any issues with a direct fault with the cam belt / tensioner will be done under guarantee. (I pointed this out to VW)

Any replies will be most welcome. Thaks in advance.
VW 97 Pasat Tdi belt Problems - BB
Further to my last post, VW have contacted me to say that the belts and timing are ok, but I have a loss of compression. No more.

They say that they are going to have to take the head off to see what the problem is.

Can anyone give me any advice or info before I have this done?

Once again, thanks in advance.
VW 97 Pasat Tdi belt Problems - Aprilia
Presumably the alternator light came on and you lost PS because the engine stopped?
If it stopped suddenly like that, and the cambelt is OK but you have no compression then I would prepare yourself for a big bill (snapped cam; cam/crank pulley loose etc. etc.).
VW 97 Pasat Tdi belt Problems - sean
BB, I have several questions for you, which may help with your answers.
1. "VW" have not been involved at all, have they? I think you are referring only to a VW franchised dealer.
2. If the cambelt jumped recently, how do you know it jumped 1, 2 or 4 teeth?
3. The passat TDi camshaft is not woodruff-keyed to the camshaft pulley to permit millimetric adjustment of cam timing. It is as critical as that. You find crankshaft datum pointer on flywheel above clutch bellhousing, lock fuel pump with peg and align camshaft precisely with feeler gauges onto pegged camshaft.
4.If your belt has slipped, likely a piston has bent a valve.
5.If your dealer did not tighten cam pulley adequately to camshaft, it could have slipped, to give the bent valve now.
6. the link with the alternator belt is that both are driven by the crankshaft pulley.
Before the alternator belt problem, how old was the cambelt? when was it last changed? If it was loose and in need of changing, that could explain why it slipped. Unusual as it is a toothed belt. properly tensioned, it should not have slipped.
Please give more info as to mileages etc.

What guarantee do you think you have? The £15 belt may be guaranteed (unlikely, as makers will say service life depends on how it was fitted) and this is an area for a garage to cover tracks by blaming other component failures.
VW 97 Pasat Tdi belt Problems - JohnM{P}
Could a slight misalignment of the camshaft pulley on the camshaft be a cause of (slight)loss of power? My current 110TDi Golf is definately slower full welly X to Y mph in top over a specific stretch of motorway compared to my 110Passat (and 110TDi A4 Avant and Golf pool cars I've had in the last couple of years), but is not obviously slow on first driving. (New turbo at 30k service, 40k service on Sat so suggestions welcome!)
VW 97 Pasat Tdi belt Problems - BB
Thanks for the reply Sean.

1: Yes it is a VW dealer
2: The cam belt jumped when the alternator belt snapped and sent remnants into the cam cover and caused the cam belt to jump. VW dealer informed me that it had jumped. This happened approx 6 weeks ago with 120,000 miles on the clock.
6: The alternator belt was changed 6 weeks ago by the side of the road by the RAC. Because the timing was out after the alternator belt snapped (it did start, but ran rough), I took it to a VW dealer in Nottingham for a cam belt and tensioner change. This was at 120,000 miles. Everything seemed fine until yesterday morning (6 weeks trouble free) when the car lost power and the alternator light came on. The car now has 123,000 miles on the clock.
At first I assumed it was the alternator belt again (belt, tensioner) but when I checked under the bonnet, the belt was ok. I then called the RAC who towed me back to VW dealer. I assumed that it was a cam belt fault due to the exact symptoms of when it jumped 6 weeks ago. However, the car would not start this time.

Basically I bought the car with a FSH in April with 114,000 on the clock.

The problem I have is to whether the VW dealer would admit to the problem of an incorrectly tightened cam belt. They are not telling me how many cylinders aren't getting compression and want a big chunk of £ to take the head off to look.
Even if it is because of negligence on the dealers behalf, proving it could be a difficult matter and I will also have to foot the bill if I cant. Whereas if I take it to a local independent, I will be charged half the price, but wont have any comeback to the VW dealer.

Stuck between a rock and a hard place i think.

Any more help will be gratefully recieved.


VW 97 Pasat Tdi belt Problems - madf
" Because the timing was out after the alternator belt snapped (it did start, but ran rough), I took it to a VW dealer in Nottingham for a cam belt and tensioner change. This was at 120,000 miles"

An alternator belt fail should not affect timing.. so I assume engine was damged at that time due to prior cambelt failure.. and evntually bang?

Did you buy a warranty with it? If none then prpeare for £500+ bills or more if piston damage:-(

BUT if they sold you the car and the damage caused by snapped belt, it must be their problem.. if they are the only people to service/work on it since you bought it..

VW 97 Pasat Tdi belt Problems - sean
BB I am very unhappy about this. I see you quote FSH. Was the cambelt changed at 60k miles? This is the correct interval for this engine.

In April, at 114,000miles, you were 6000 miles off a second belt change.

I strongly suspect that (and would be amazed if not) that what happened when the alternator belt snapped was your cambelt moved 2 to 3 teeth, a valve hit a piston and was bent.

How anyone can say (from your first post) that the engine was undamaged then, if they did not whip the head off and look, I do not know. The engine will have been re-belted, fingers will have been crossed at the garage, and you will have driven off, probably with a valve or two severely bent. As you have driven, these valves never properly seat. Exhaust gases travel up the stem and weaken them further. Next thing, snap. A valve breaks up and you lose compression. Sometimes the valve head gets stuck in the top of the cylinder, hit by the piston and the engine stalls, if you're lucky, or blows up, if not.

I expect a bill here between £300 and £800. A replacement engine (unlikely) would be £1100 to £3400.

Good luck, mate.
VW 97 Pasat Tdi belt Problems - DavidHM
The good news is that the dealer who sold you the car in April is still liable unless he can prove on the balance of probabilities that the fault was not there at the time of sale.

Similarly, if you can show that the belt change was carried out without reasonable care and skill, the dealer is liable. It doesn't have to be beyond reasonable doubt, just on the balance of probabilities.

This applies whether or not you take the car to a VW franchise for the repair, although you will find it easier to get money out of the dealer if they carry out the repair too. An independent report while the engine is still damaged may be your best way of establishing causation. If you can show causation you will of course get this money back too.

Otherwise, you are on your own.
VW 97 Pasat Tdi belt Problems - BB
Thanks all for the replies.

Things have advanced a bit further and I will write more about what I have found later on when I finish work.
VW 97 Pasat Tdi belt Problems - BB

Many many thanks for your replies. They make a great deal of sense.

I spoke to the VW dealer yesterday and suggested that a small claims court arbitrate in our dispute.

The head still has not been taken off yet. But I have some photos of the damage from when the rocker cover was taken off.
The problem I have is that I cannot afford for a main dealer to carry out the work for me.

I will post again once I have some more information.

VW 97 Pasat Tdi belt Problems - BB

Your explanation also solves the loss of power steering / alternator light situation that I encountered moments after I lost power. The engine must have stalled.

I was too busy trying to avoid traffic in other lanes (whilst pulling onto the hard shoulder) to notice that the car had stalled (and the radio too loud). I think I was more concerned about not hitting the Eddie Stobart trailer that was on the inside of me!


VW 97 Pasat Tdi belt Problems - Malcolm_L
Noting Sean\'s comments about the high probability of bent valves the first time round, shouldn\'t the garage have at least checked compression on all cylinders and also checked crankcase pressure as well?

IMHO the fingers crossed approach is negligent - it\'s very likely that the damage you now is as a result of their sloppy approach.

Is the garage AA/RAC approved - could be worth your while getting them involved.

Best of luck

VW 97 Pasat Tdi belt Problems - DL
But surely if any valves were bent after the first belt jump, the engine would have run roughly*? Was there any sign of this?

* Due to loss of compression
VW 97 Pasat Tdi belt Problems - BB
The engine did run as expected after the first belt jump. How much valve damage would be neccessary before it was felt? Could the first belt jump caused a fracture which over time developed into the current situation?
VW 97 Pasat Tdi belt Problems - DL
Any small (insignificant) amounts of valve damage would be detrimental to the engines operation - and any stresses/cracks etc caused during the original failure could manifest themselves at a later date, as I fear has happened here.

Did it start cleanly (smoke/vibration?) after the first belt failure? Any valve seat misalignment would result in a loos of compression (on that cylinder...) and cause an imbalance/excess smoke.
VW 97 Pasat Tdi belt Problems - BB
When the cam belt was replaced, there was no noticable difference in starting and driving. I did not notice anything different about the general drive / sound of the car since the cam belt was replaced.

I have only had the car since April this year, so I was still getting use to the sound and drive of the car anyway, so I may not have noticed any minor changes. But it did seem to be running ok up until the breakdown.
VW 97 Pasat Tdi belt Problems - madf
All you need is for 1 valve to touch a piston on the belt break and either bend the valve very slightly or chip the piston crown a little. The effects would not be noticeable at first but a bent valve will eventually destroy the valve seat leading to a loss of compression and rough running . A chipped piston may eventually lead to a crack in it leading to excessive oil consumption.

(You may be unlucky and have more than 1 bent valve).
VW 97 Pasat Tdi belt Problems - BB
Thanks for the note madf. I have learnt a lot about valves in the last few days!

Compression tests show a problem in cylinder 2 only. The car is still at the VW dealer, but will be towed away this weekend for it to be looked at.

Thanks all to those who have posted. All will be revealed soon!
VW 97 Pasat Tdi belt Problems - sean
Please do not repeat this anywhere outside this Forum. Truthfully, there will only be trouble for me if you do.

Much money has been spent to make life easy for production engineers to assemble designs. Knock sensors on petrol engines to retard timing that is slightly advanced ( or using low-octane petrol) etc.

A valve is sealed by very close contact with it's seat. If you were doing this at home, much time expended lapping it in etc.

In production, it is machine assembled.

What do I need to do to minimise rocking couples from imbalances?

You can ruin me, if you read this in a particular way. I just will not then return here.

Please read between the lines and understand that what has been said here so far, by many, is correct.

No surprises expected.
VW 97 Pasat Tdi belt Problems - DL
\"Please do not repeat this anywhere outside this Forum. Truthfully, there will only be trouble for me if you do.\"

What on earth are you on about???
VW 97 Pasat Tdi belt Problems - sean
I was reprimanded for posting detail that would bring litigation to my employer.

The comments I post are my own opinions, only.
VW 97 Pasat Tdi belt Problems - DL
Ah, I see......a tricky area indeed. Understood.

VW 97 Pasat Tdi belt Problems - BB
Understood Sean.

Value my car