Email Tim with your questions

I recently bought a second- hand Nissan X-trail,noticed a white creamy looking deposit on the oil cap, dealer told me that it was a normal condensation, unfortunately these feels like it is more than the condensation. Lately i,m loosing a lot of water in the radiator, needing to top-up, on several occasions when I start the car it smokes and feels like it is misfiring, this though is momentary as when the car warms up it has a smooth feel to it. I'm worried just in-case my engine is shutting down slowly. The creamy deposit is ever present.

Name and address withheld

The creamy deposit is oil mixing with the water in the cooling system. The head gasket is the most likely cause and a coolant system pressure test or a head gasket “sniffer” should confirm this. If it is the head gasket, I would strongly recommend a trip back to the dealer. It is illegal to misrepresent a car if you are a trader and I would argue that if you pointed out the creamy deposit and he told you it was normal, he’s misrepresented it. Full refund or pay for repairs would be my start point.

My wife’s Kia Rio has developed a problem with the central locking. When attempting to gain entry with the key fob, the locks just keep locking. Even when we got in the car via the passenger door we were still unable to open the drivers door. Help

Tony Pilbeam, UK

You will need to take the inside door panel off to sort this out. If the locks keep unlocking then immediately locking again, it’s an electrical problem and is usually caused by water getting past the weather strip on the outside of the window and into the solenoid connections. However, from your description, this sounds like the linkage to the driver’s door lock.

We own a Skoda Superb Elegance 2.0ltr TDI PD with a DPF(diesel particulate filter). I am more than a little confused. I understand that the DPF can become blocked under certain conditions, mainly if the engine and thus the exhaust is running at temperatures to cool to burn off the soot. According the the Manual, should the warning light come on. The car must be driven at 1800-2000 revs in 4th 5th gear for a period of 15 minutes at which time the DPF should regenerate its self. This is where the confusion arises. If the car is being driven in the manner described surely the engine and the exhaust will be running at its coolest. If the car is doodling in traffic would not the engine and exhaust be running at its hottest? Why is forward speed necessary for regeneration of the DPF? Could not the engine and exhaust temperature be raised to a temperature necessary to burn of the soot with the car stationary after all 2000 revs is 2000 revs whether stationary or moving? Why must the car be moving? Hope you can help clear my confusion. Regards, Jenks

Geoffrey Jenkins, Winchester, UK

The DPF is simply a fine filter in the exhaust system which removes tiny soot particles from the exhaust. It clears itself when it gets hot enough to burn the soot away, but hot enough is very hot! The heat comes from the exhaust gas, but engine temperature and exhaust temperature are not linked in the way you assume. The engine temperature rises when you’re stationary because there’s no airflow through the radiator to cool the coolant. The electric fan comes on to provide that airflow instead of the car’s motion doing it. However, when you’re stationary, there’s no load on the engine and so very little fuel is being burn, meaning that not much heat is going through the exhaust. Think of a pan of water on gas cooker with the flame turned down really low – the water stays quite cool. Turn the gas up and you burn a lot more of it, producing much more heat, so the pan heats up quickly. In just the same way, when the engine has to push the car along, it burns more fuel, so more hot exhaust gas passes through the filter and heats it up enough for the soot to burn.

Could you possibly let me know which kind of engine you think would be the most efficient for our circumstances, diesel, petrol, diesel/hybrid or petrol hybrid? We (family of four) do about 5,000 miles a year, most journeys are short, 2 to 5 miles on B roads, a 30 mile drive once a month and 1,000 mile round trip once a year or so. We live on a small hill (200feet) which is quite steep in places.

I am thinking of getting a Econetic/BlueMotion or maybe waiting for VW or Peugeot hybrids. As so much of our driving is short would diesel be efficient and would hybrid have a chance to charge? We have had our current car (1.6 Laguna) for nearly seven years and would like to replace it with something that would easily last another seven if not more. Ideally it would be cheep to run and safe, speed performance is not a priority.

Many thanks,

Name and address withheld

It sounds as if you rarely sit in a traffic jam, which is where a hybrid really comes into its own, and with the hills and short trips I doubt that you would spend much time without the petrol or diesel engine running. So, a hybrid is not going to give any real benefit for the type of driving you do and I recommend that you buy a small, efficient petrol or diesel car now. Unless you have a particular liking for Ford and VW, don’t restrict yourself to their “green” Econetic/BlueMotion brands – there are now lots of cars in the fuel stretching VED (Road Tax) Band “B”, and more coming out every month. Look for the coloured carbon label displayed by the cars in the showroom. It gives a breakdown of typical fuel and road tax costs which will help you pick the best car for your wallet and your requirements.

In the last 3 months my wifes 36,000 mile 03 Mini Cooper has had both the brake pads replacing and now the clutch this will cost £1100 to replace. she is not an aggresive driver as the 2 occurances may suggest. BMW will not concede that these are faults with the model but a quick search on Google of "Clutch" and "Mini" will convince you otherwise. So when does a manufacturer have to acknowledge certain faults are for them to put right?

Bruce Anderson, Bristol, UK

Your wife’s MINI has done around 7,500 miles a year, which is below average and might indicate a fair amount of town driving. If so, 36,000 miles is not unreasonable for a brake pad change. MINI clutches certainly have a reputation for wearing out at lower mileages than other cars – around 50,000 miles is typical, but again it will be less for a car doing a lot of town driving. £1,100 is a bit steep – shop around and you should get the price down to around £700 – 800. The car is out of warranty and these are all wear and tear items, as opposed, for example, to the gearbox or power steering, which also give problems on the MINI, but you expect do them to last the life of the car.

How does the Tata Nano's engine work? I would like to know the technical advantage of the car.

Anisha Goel, Delhi, India

A four door car which will carry a family in comfort, powered by a 600cc 33bhp two cylinder engine...where have I heard that before? Oh yes, a car that met the needs of its target audience so well that over 5 million were built, from 1948 to 1990. I’m not talking about the Morris Minor or the Mini, brilliant cars though they both were. I’m not even talking about the much vaunted VW Beetle. The car I’m thinking of outclassed all three of them in terms of perfect design for the time and the market – the Citroen 2CV. The parallels with the iconic 2CV are undeniable – and just as the 1948 “Deux Chevaux” was a very advanced design for its day, the Nano is in no technological backwater. Designed from the outset to be low cost to buy and to run, but contrary to many peoples’ assumptions, that doesn’t mean it’s basic, flimsy or unsafe. The aim was to build a car that is a realistic upgrade ambition for people with scooters, motorcycles or the three wheel trucks that abound in India. Weight is kept down, but the body is designed to modern safety standards with crumple zones and strength where it’s needed. The basic car doesn’t have aircon or power steering, although I gather they are options, so the engine’s power, minimal though it is, is all used to turn the wheels, giving an acceptable performance. The engine itself is all aluminium – which again keeps weight down – and is a two cylinder 633cc, 33ps unit which, being so small, is both economical and low emission. It’s fuel injected and carries all the electronic control you’d expect in any modern engine – and so it should, it’s the cheapest way of making an engine work!

So, well done Tata is my verdict. The car doesn’t have the sort of equipment, performance or refinement that the marketing folks tell us we all demand in Europe, but with a price tag of £1,250 or thereabouts, and minimal maintenance and fuel costs, it’s the sort of car that deserves to be a cult car, if only because it isn’t intended to be one!

Hi Tim,

My mother's driving style is giving rise to arguments between us! She's 68 and not that interested in motoring. She covers about 10000 miles a year in her '05-reg VW Touran 1.9 TDI (105 bhp). The car has a manual 'box (and 28000 miles on the clock). My concern is her tendency to be in too high a gear. Very often she's in, say, 5th, when 4th (or even 3rd) would be far better. (At stop-start 'crawling' speeds, it

rarely occurs to her to change from 2nd to 1st. And, she sometimes pulls away from a standstill in 3rd!) I have urged her to change down ahead of signs that the engine is 'labouring' - but (when road conditions dictate a lessening in speed) she tends to wait until the engine does 'labour'. (It's as though she isn't reminded of the need to change down until the engine note 'grumbles', and the car subtly vibrates.) I warn her that her approach may result in her engine becoming 'prematurely tired'; she contends that, thanks to the engine's degree of 'low-down pull', it's easily robust enough to 'shrug off' the effects of her style of driving. Please: am I being too harsh on her? (She hopes that the car will last for many years.) Many thanks in anticipation of your advice.

Graeme Garden, Near Stafford, UK

Oh dear! It’s bad enough giving an opinion on someone’s driving from the back seat, let alone via the internet. On the one hand, the Touran has a very torquey engine with lots of low down grunt. I give a lot of eco-driving advice and demonstrations and getting people to use a higher gear is one of the things people find hard to get used to, but the fact is, most of us drive around in a lower gear than modern torquey engines will tolerate and fuel economy suffers as a result. So, to an extent, well done Mum! On the other hand, pulling away in 3rd will stress the clutch and the (very expensive) dual mass flywheel, so she should really stop doing that straight away. My best advice is to recommend getting in touch with your local IAM group. They offer a “Drive Check”, which isn’t a test and isn’t at all intimidating (or so they all tell me!) For £25 she will get an objective, friendly assessment of her driving and some pointers as to where it can be improved.

I have a 2001 1.1 fiat punto. Modest mileage 58K. Reasonably well maintained/serviced. There is a very loud high pitched whine which starts at a couple of thousand revs in first gear, increases in pitch up to about 5K revs, stops, then when the next gear is selected it starts again and repeats in every gear. Seems to stop after about 10 mins/once engine warms up. Very loud and disconcerting noise. Had head gasket replaced and think noise started after that. Fan belt seems tight enough. Mechanics have suggested it could be either clutch bearing plate or diff bearings? I do have some clutch judder. Had similar clutch judder (but not the whine) on earlier punto until clutch actually shattered. Car is getting old and worried potential big damage/bill on the way.

Any ideas?

Rob Rowan, Newcastle, UK

You can carry out a simple test of your own to narrow down the fault a bit. Go out in the morning and before you start the engine, press the clutch pedal to the floor and hold it there, with the gearbox in neutral. Start the engine, keep the clutch pedal pressed and raise the engine speed to about 2,500 rpm. If you hear the noise then, it could be a slipping “fan” belt (it doesn’t actually drive the fan, but we all know what you mean) or it could be the clutch release bearing. If there’s no noise, keep the car in neutral and let the clutch pedal up with the engine still at about 2,500 rpm. If the noise starts, suspect the gearbox, or again it could be the clutch release bearing. Gearboxes do give problems on the Punto, but since you have to remove the gearbox to get to the clutch, they can both be checked at the same time. If there’s still no noise until you put the car in gear and drive it, suspect the gearbox or final drive (otherwise known as the diff). Fist final drives are a bit prone to failure as well, although the noise you describe is not usually associated with diff problems. Armed with this more precise description of the symptoms a garage will have more to go on and should be able to give a more accurate diagnosis.

During a recent cold spell I scraped the windscreen and side windows with a defective plastic scraper which has left noticeable scratches on the glass. What is the best way to remove these scratches?

Patrick Elliott, Woodbridge UK

Jewellers’ rouge is the stuff you need. It used to be fairly difficult to obtain, but thanks to e-bay you can get it easily nowadays for about a fiver.

6 months ago i purchased or my first car a 2002 smart fortwo. lovely little runabout to fit saxophone etc in however i have been victim to the 60,000 mile cracked manifold/seized piston fault. How can a car built under licence from mercedes be so inherently faulty without some comment from daimler Chrysler any advice on who to talk to on this issue would be great. Thanks

Tom Lea, Sandbach, UK

I don’t know the history of this car, but it has done at least 10,000 miles a year, which is high for a Smart – typical miles for a 2002 model would be more like 37,000 than 60,000. That sort of mileage could indicate at least some longish motorway trips. I regularly get passed by Smarts being urged along at well over 70mph, and although the little engine will get you up to that speed, the car was designed to be a city car. Just look at the output in relation to the engine size. Getting 54 to 60 or so bhp out of a 600cc engine is stretching it – it’s the equivalent of around 100 bhp per litre, which puts it in the high performance bracket – size for size it compares with the Toyota VVTLi 190 bhp engine, Ferrari lumps, Honda S2000, etc. But, they are a lot bigger and will carry their cars to 150+ mph, so at UK motorway speeds they’re not in the least stressed. The Smart engine most certainly is – it’s running at pretty much maximum output on a motorway and if you run a high performance engine at or near its limit for any length of time, expect problems. That’s not to say that you have been thrashing it along a motorway, but I suspect a previous owner has and that’s what shortens the life.

The car’s well out of warranty and it’s unlikely that Smart is going to contribute to the repair, but you can always ask. For the future, my advice is that if you like the car and want another one after you’ve had your money’s worth out of this repair, look for a car that’s done no more than 6,000 miles a year and take out a warranty from one of the many firms who offer them.

As for the bit about being built under licence from Mercedes, well, if it’s any consolation, it’s nowhere near as bad as the mk1 A class and doesn’t rust round the rear wheels like the C class... Perhaps Mercs ain’t what they used to be!

I bought a new Nissan QASHQA 1.6 petrol some months ago, while it has many attractive features, I am now worried about it’s engine size to body weight ratio. If the gear change is slightly slow the engine seems to be in high noise. As a matter of fact one comment I reed from an experienced tester suggests that driving the 1.5 Diesel and 1.6 petrol is like tagging a tone of steel. Should I be worried that as the Car get older, the problem could even get worse. What do you advice? Worth pointing it’s good petrol consumption and insurance group.

Name and address withheld

It is a heavy car for this engine and, being petrol, it’s not that high on torque so you will need to use the revs. No, it won’t get worse, or not until the engine’s badly worn. The all new 2.0 diesel is probably more suited to the car if you want something that sounds more relaxed, although there are reports of disappointing fuel consumption from it, so if you’re happy with yours, learn to accept the different noise it makes and enjoy it!

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