Hi all

I just had the cambelt changed, on my 53 Skoda Superb 1.9tdi at 29000 miles. Now there is a horrendous noise when I switch the climate control on. The VAG dealer says the unit motor may be on its way out, but it was fine until the cambelt was changed. Please help!

Ripink

I suspect they have damaged the clutch on the front of the aircon compressor - the belt for this has to come off in order to change the cambelt.

Have a careful look at the compressor pulley whilst the engine is idling with a torch whilst an assistant in the car alternates between "auto" and "econ". If it's not running true it's damaged or the 14 AF nut on the compressor shaft is loose - a very common problem.

Be very careful when you make this check. The electric fan beside the engine driven unit should run at half speed when the aircon is selected.

rotodiesel.

>>>or the 14 AF nut on the compressor shaft is loose - a very common problem.

Yes, I recommend loctite or even Superglue on this one.

My Octavia's airco clutch still works, but was half worn out due to loose nut.

The airco clutch is stlg200+ part at the stealer.

A couple of weeks ago I bought a Skoda-approved used Superb: 04, 1.9 PD Comfort, 34,000 miles from a main dealer, and would really appreciate some help because I think the exact problem described here has happened to me, but the dealer is lying to me.

When I first looked at the car I had it for two hours and everything checked out fine as far as I could tell, being no mechanic. The cambelt change was due and the dealer said they'd do it. As ever with dealers, I was dubious, but I figured I had a lot of comeback if things went wrong, it being a Skoda-backed warranty and an "award-winning" dealer (yeh, I know, don't laugh).

I picked the car up on a Saturday. The next day I noticed the aircon made a terrible racket when I turned it on; not fans, but from the engine area. In addition to that I could hear a noticeable noise on accleration that both my wife and I are certain was not there when I test drove it. The sound is a bit like that of a worn brake on a disc in character, but it's not brake related, it's a rubbing/whirring sound that either stops, or more likely just drowned out at speed or under hard accleration. It can be heard when in neutral and the engine is revved.

That's when I found this thread. I took the car back the following Saturday. All that week the noise was there if I turned the aircon on to check. It was still there when I took it back to the dealer. They couldn't have been more helpful, gave me a courtesy car straight away and promised to look at it. I gave them a print out of this thread, as a pointer, just in case. As the noise was so obvious and had been there all week I didn't even get them to listen to it at the time, which I regret now.

On the Monday, around midday, I got a phonecall from a mechanic saying he couldn't hear any noise. A little later I went in to fetch the car and it sounded ok. One of the salesman said he hadn't heard a noise when he test drove it on the Saturday. The head of the service department also said, patronisingly, that reading forums can be like reading medical things, makes people worry unnecessarily. I decided to remain calm, saving things for later, if needed...

As I couldn't hear the aircon noise any more, there was not much else I could do. I got them to stamp the service record that they had done the cambelt change - something they had not done when they had the car in preparation for a week. Interestingly, the Service Dept Manager who updated the service record went into a back office out of sight for what seemed a long time given it was just a book entry, before returning with the booked stamped. I don't know why he didn't do it at the desk as he had all the records on his PC in front of him. I suspect he went to check exactly what had gone on because he was signing his name to it.

So I have the car back and the aircon noise has gone, but the acceleration noise is still there. Over the course of the past week it has subsided a little, but it's still audible. I feel quite sure the dealer messed up the cambelt change and then corrected it, before pretending there was nothing wrong. I say corrected, but because of the engine noise, I think they've damaged something.

Since then, I've also discovered that the intermittent wiper has a mind of it's own. The switch seems imprecise and it makes it's own mind up about how long to delay. The four settings all do this, one of them actually puts the wipers on constant.

And finally, the radio also has intermittent interference, something I mentioned when I took the car back in about the aircon, but which they didn't even mention when I picked it back up (see above about keeping my powder dry for later). It's not a tuning problem because it sets itself perfectly to the exact frequency for national and local stations, but they sometimes have bad intereference, sometimes not. It happens all over the country, so it's not a local problem. It's not the speakers because CDs work perfectly.

So. I now want to have the cambelt and engine noise checked elsewhere and I'm going to approach Skoda UK for their views, and where to take it to have the radio and wipers sorted out.

Before I do all that, I'd really appreciate some help with some questions I have.

1. Is it possible to tell fairly easily if the cambelt has been changed, and changed correctly?

2. What problems could the dealer have caused as a direct result of working on the cambelt, that could cause the rubbing/whirring noise?

3. Is the radio a known problem area?

4. Are the wipers a known problem area?

5. Another other advice anyone can offer.

(Apologies for the long post)

Thanks in advance, hopefully.

FSC

@ FSC

1 - No

2 - Probably none

3 - Not to my knowledge

4 - Not to my knowledge

5 - Here goes, when they changed the belt they had to take the front of the car apart and obviously the drive belts on the aux circuit, sometimes when putting it back together the tensioner doesn't do it's job 100% (look just below the alternator) and sometimes it overdoes it and stresses the alternator pulley, the squeal sounds like this and is highly annoying, a friend had a new tensioner fitted and 5 weeks later the alternator pulley snapped off, I suspect the dealer has sprayed all the pulleys with lubricant but this will only last a while before the noise returns, then you need to get it seen to asap as alternators ain't cheap or in supply for that matter (mate waited 3 weeks for one) sadly you join the masses of us who own a quality car backed up by what can only be described as a back street garage experience, as for the wipers they do seem to have a mind of their own once the sensor decides to set em off, this isn't a Skoda thing though my VX's did it also, very hard to get the right sweep all the time. hth.

1. Remove engine top cover and unclip upper timing belt cover (no tools required for this) Push car slowly forwards in top gear to turn engine over and observe that the lettering is clearly visible on the back of the cambelt. It wears off after about 5k miles.

2. The dealer can introduce all kinds of problems when working on this part of the car. They employ poor quality labour with no motivation to do a good job - they just want the thing out of the door. These are fairly complex cars and due to poor design, quite a lot of dismantling has to be done to do a routine job (belt change). Very careful assembly has to be done in order to avoid problems. You can run the engine with the upper cover and belt cover off (make sure you put the dipstick back in) and check that the belt is running properly and not fouling anything. If there is the slightest assembly fault in this area, there will be big problems later.

3. & 4. Electrical problems are common on these cars. Check for poor connections and dealer disturbance. The radio in the Superb is very poor in terms of FM RF performance. The £50 Halfords job in my wife's car out-performs it on the same route.

6. Avoid VAG dealers at all costs. Find an independent who has traded from the same premeses for a long time, has a good reputation, low staff turnover and who is motivated to do a decent job on your car. They do exist.

VAG diesels of this era are great machines - I've just managed 800 miles from a tank of fuel on holiday with my 130 PS Superb. They're too good to let the dealers bugger them up.

rotodiesel.

@ FSC

sometimes when putting it back together the tensioner doesn't do it's job 100% (look just below the alternator) and sometimes it overdoes it and stresses the alternator pulley,

In my experience with auxiliary belt tensioner problems, which usually manifest themselves when the alloy casing next to the damper breaks, the cause is usually the the one way clutch on the alternator pulley seizing up. I have seen a case where a dealer replaced an alternator (Octavia TDi) and put a non freewheeling pulley on the alternator, sometime later the tensioner casing broke. This is an example of the symptom getting fixed, rather than the cause. In all the cases that I have seen of the the tensioner breaking, every time the alternator pulley did not freewheel as it was designed to.

We've had air conditioning belt noise after carrying out cam belt and water pump changes, but this has always been down to coolant on the pulleys, which soon disappears.

A correctly working one-way clutch in the alternator pulley is absolutely essential - the auxiliary drive will not run properly without it.

To test - with a stationary engine - vey carefully put a small screwdriver into the front of the alternator and try to turn the internal fan blades clockwise as you look at it. They should turn easily and instantly lock if you turn them the other way. Be very careful not to damage the copper stator windings when doing this test.

In my experience, the one way clutches cause more trouble than the tensioners and a defective alternator clutch will nearly always damage the belt tensioner - and a few more things if you don't replace it promptly.

rotodiesel.

Just one question to satisfy my ignorance, is it only the TDI engines that get freewheeling alternator pulleys and if so why? Also, in general why is a freewheeling pulley needed? (it just that I've never come across them before - well don't think I have!).

Unless its something random like they havent clipped the bonnet cable back in properly and its now rubbing on the a/c fan and making a noise.

Two issues here. Noise in the cambelt drive after a change is often due to an incorrectly fitted cover - usually the lower one. Any poor workmanship here will cause big trouble - I always run an engine with the upper cover off following a belt change and make the most meticulous inspection to make sure all is well.

The freewheeling pulley on the alternator is needed because of the severe torsional oscillations produced by the diesel engine, coupled with the very high drive ratio from the crank to the alternator. This has the effect of multiplying the oscillation in direct proportion to the ratio (about 5:1 for a VAG PD). Without a freewheeling clutch, at idle, the alternator rotor will be violently accelerated in each direction as the engine fires on each cylinder and the whole belt drive system becomes overstressed. It's very well worth while making a regular visual check on the auxiliary belt drive with the engine idling - it only takes a few seconds and could save a lot of damage.

rotodiesel.

Thanks rotodiesel, I'm just a petrol head DIYer that has in the past dabbled with a few indirect injection Landrover and other Simms and CAV DPA fuelled sort of engines - so don't appreciate what the modern car diesel engine is all about.(not much Kygas talked about these days!).