Ask Smithy: automotive advice | news.com.au Australias leading news site

CARSGUIDE'S used car expert Graham Smith helps readers with their motoring problems.

NO DASH TO FIX CRACKS

IN COMMON with reader Nicole Holzheimer, we have a Toyota Prado with a cracked dash, exactly where Nicole's has cracked, right over the instrument panel near the vents.

This is a car we paid $56,000 for, no less, and it's got an ugly cracked dash. Toyota wasn't the slightest bit interested even though the car was only 12 months out of warranty. Our car is garaged every day, the dash is regularly cleaned with Armorall, we have a dash mat, and we always use a reflective windscreen cover.

We're devastated, our car has lost its re-sale value. Toyota would not even offer to repair it or give us details of who could repair it, so instead of trading it on a newer model as we'd planned we're forced to keep it simply because no one will pay what it would be worth. I am so disappointed by Toyota's response, especially when we are not the only ones with the problem.

- Kim Whitehead, email

SMITHY: It's disappointing that this happened, especially when you've gone with a brand that's known for the quality and robustness of its vehicles. I hope Toyota rethinks its response on this matter. Meanwhile, you have a couple of options. There are dashboard crack repair kits available from auto stores that may help you or there's Uticolor (www.uticolor. com.au), which specialises in plastic and vinyl repairs.

CRANK IT UP

MY 1999 XH Ford Falcon Tradesman utility suddenly stopped running at a set of traffic lights and had to be towed home. There was no spark evident when a plug was removed and the engine cranked over a little. There was absolutely no sign of it firing up. I have heard that the crank angle sensor may have failed and possibly the coil has too. What can I do?

- George Hannaford

SMITHY: Replacing the crank angle sensor is a good start as that's most likely the problem, then look at the coil.

GEAR DAMAGE

UNTIL recently my 1996 EL Ford Fairmont has been reliable but it has been overheating and using coolant. I was advised to replace the radiator, which I did and the overheating stopped, but it's still using a small amount of coolant. I have also noticed that the auto transmission is labouring through the gear changes. Should I change the transmission fluid, or have the transmission serviced?

- John Archer

SMITHY: I'd say the transmission cooler failed in the old radiator and allowed coolant into the transmission. Replacing the radiator has fixed the coolant leak, but it sounds as if it's too late for the transmission. Try a transmission service - you might be lucky. If that doesn't do the trick, you could be up for a transmission rebuild.

FLUID SITUATION

THE handbook for our 2005 Mazda2 automatic specifies checking the automatic transmission fluid level every 20,000km but there is no recommended interval for changing the fluid for vehicles in Australia or New Zealand. In other countries it is every 50,000km. My local dealership believes the transmission is "filled for life" but, when pressed, the chief mechanic suggested changing the fluid at 100,000km. Why would Australian or NZ cars differ in this respect from those in other markets. What is your recommendation?

- Lawrie Marsh

SMITHY: Car makers evaluate local conditions when setting service routines and Mazda has decided not to recommend an interval for changing the fluid in cars sold here. Auto transmission specialists generally recommend changing oil every 50,000km and having a full service carried out every 100,000km or so. Based on this, I'd have the fluid changed.

BRAKE PROBLEM

A FRIEND is having problems with the brakes in his new FG Falcon XR50 ute. The brake pedal slowly sinks to the floor if he holds his foot lightly on the pedal, as you would at traffic lights. The dealer says it is normal and is to help stop the driver's leg being broken in the event of a collision. A mechanic friend said this should not happen and is a safety issue. He thinks the problem may be undersized cups/seals in the brake master cylinder. What do you think?

- Lynton Farmer, email

SMITHY: It shouldn't happen and the dealer's explanation is nonsense. Check the brake master cylinder and brake booster for leaks.

FUEL FOR THOUGHT

I HAVE been thinking of installing LPG on my 2004 Holden Commodore VY II and was wondering if that was considered a good idea for this make and model?

- Elham Ghalayini, email

SMITHY: There's no problem converting the VY II V6 to LPG. However, I suggest using a quality injection system to avoid encountering problems with the conversion.

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NITROGEN: yes or no?

OCCASIONALLY we get asked about the benefits of inflating tyres with pure nitrogen instead of good old air available at our local service stations.

Generally we've argued against the use of nitrogen, saying that the benefits for the normal motorist are minimal and can't be justified when you consider the cost and availability of the gas.

Air is mostly made up of nitrogen and oxygen, which is fine for normal use but oxygen does pass through the rubber of the tyre, causing a slight loss of pressure over time.

Nitrogen does this too, but at a 30 per cent slower rate. The pressure loss is less with nitrogen but regular pressure checks are still required.

When you do need to re-inflate your tyres to adjust for the pressure loss you have to find an outlet with nitrogen.

Proponents of nitrogen also argue it is a more stable gas and delivers more predictable tyre performance.

This is true but nitrogen is really only beneficial in extreme conditions, such as motor racing - which generates higher tyre temperatures. There's virtually no benefit for ordinary motorists.

Moisture in the air chamber can cause the pressure to build up as the tyre temperature climbs but nitrogen, as a dry gas, doesn't support moisture, so doesn't have the same pressure increase.

In extreme conditions, this can affect a car's handling but at the temperatures generated in normal driving on the road the benefits are almost non-existent.

Some tyre outlets promote the use of nitrogen but charge a fee, which can amount to as much as $25 for a set of five tyres.

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