Ask a mechanic - 01/04/06

A: There's an almost endless list of possibilities, but hot favourites have to be: bad spark plugs, tracking HT leads, a dirty/worn ignition distributor cap or rotor arm, a faulty ignition coil, and dirt or water in the fuel. It might also be a poor connection or faulty solder joint in the engine management module. Take yer pick!

KOREAN SCREECHER
Q: I fitted three drive belts bought from a motor store, to my Hyundai. These were fine for four months, but now there's a screeching sound whenever I turn the steering wheel - worse on very cold days. The dealer says it's because they're not genuine Hyundai belts.
Posted by: virginia758

A: We doubt that's the reason, but inadequate power-steering belt tension probably is. The reason it's worse when cold is that the rubber of the belt is harder, so it doesn't mould itself round - and grip - pulleys as well as when it's warm. Tighten it up.

ASTRA'S ALL OF A PUFF
Q: I am getting excessive smoke from my Astra diesel. The idle speed is quite high and doesn't slow down when the engine is warm; could the smoking be caused by the cold-start switch being stuck on, or is the engine done in?
Posted by: kbarkess

A: The smoking could be caused by a number of things, and a jammed cold-start mechanism is one possibility. A dirty air filter or worn injectors are others. Too fast an idle can be reduced by screw adjustment (providing it's not a modern electronically controlled diesel). A worn-out engine is usually characterised by very difficult starting from stone cold.

NEW CLUTCH JUDDERS TOO
Q: My 1991 Escort van judders badly when pulling away, even though it has had a new clutch fitted. What do you think can be done about this?
Posted by: debra.everett

A: If the clutch assembly is new (and that means both the clutch drive plate and pressure plate are new) the judder may be caused by a distorted flywheel face (you'd need it re-machined or renewed) or by a sticky clutch release mechanism. If it didn't judder immediately it was fitted, you may have a crankshaft oil leak onto the clutch plate.

FIAT'S A NON-SQUIRTER
Q: The front and rear screen 'squirters' of my Fiat Brava have stopped working, but the reservoir is full and I can hear the motor working when I press the switch. What's more, the headlight sprays continue to work. Any suggestions?
Posted by: ian_power

A: There may be a break in the supply pipes between the motor and the washers, and you'll be able to tell by activating the washer system for a while and looking for water dripping under the car. If not, a supply pipe might be kinked, or - oddly - all the washer nozzles may have become simultaneously blocked.

NO-BLOW VEE-DUB
Q: The heater blower of my M-reg Mark III Golf has stopped working. The fuse is okay, and I have changed the blower motor, but still no joy. Can you suggest any other possibility?
Posted by: jasonjohal

A: Check the voltage supply to the blower motor. It may well be via a relay that you don't know about, or - most likely - a rheostat (the speed-selection switch for the blower), and one of these devices could be dead. At least you know the motor's good, so work backwards.

WHO TO BELIEVE?
Q: At MoT I was told my brake pads and discs needed renewing. But just one week previously I took the car to an independent garage and was told the pads were okay for a few hundred miles. If the pads were okay, why did I need new discs?
Posted by: jane.thomas63

A: Nobody should leave pads on that are only good for 'a few hundred miles', as that translates as only a few days or weeks' driving, and there are months between services. You will only need to replace discs if the brakes judder, or if the tester deems them to be heavily scored or worn too thin.

FUSSY OILER
Q: I want to change the engine oil of my '94 Ford Probe to a synthetic, and presently I'm using Quaker State 10/40l. I've researched various synthetic blends, but haven't yet concluded what's the best. Could you help me choose the best?
Posted by: John0510

A: There's no such thing as 'the best', but as a rough rule of thumb, providing you're buying from a reputable outlet, the more money you spend on oil, the better the quality. We would choose a mid-priced synthetic, ensuring it's of the correct viscosity and API or ACEA grade specified for your car - and change it at the specified intervals.

A WINTER COMPLAINT
Q: I have rattling noises coming from the rear of my car, apparently from the back window. I don't know if it's due to cold weather, but when I have the heater on - and particularly the heated rear window - the rattling fades.
Posted by: royle910

A: You need to drive while somebody travels in the back seat and pinpoints the source of the rattle. It could be the parcel shelf or the suspension top mountings (they're favourites). It's normal for trim - and suspension - to creak and rattle more at low temperatures.

TAKING A DIM VIEW
Q: The interior light of my car has suddenly started to dim, although no other lights are giving any trouble. The car is a 1995 Mitsubishi Spacewagon 2-litre auto.
Posted by: gward055

A: Either it's a malfunction of the auto-dimming function of the cabin light (if your car has one) or it's that the bulb is failing because of blackening of its glass envelope. It may also be that a resistance in its supply circuit is reducing its performance.

STUCK TRUCK
Q: I have a 1998 F-150 SC truck, and I've replaced its battery. But when I turn the starter key it just won't turn over; it tries to, but the power fades quickly and it all dies out.
Posted by: seliga

A: If this is a good, new battery, fully charged, then it sounds as if there's a big electrical resistance in the starter-motor circuit. Check that the battery terminals are clean and tight, then have the rest of the circuit checked over. It could always be that your engine is partially seized... but you'd know about that, wouldn't you?

FEISTY DON'T LIKE THE COLD!
Q: My R-reg Fiesta diesel needs multiple attempts at starting, and sometimes won't start at all. This problem is accentuated by cold weather. When it runs everything seems fine; leave it to stand for three or four hours afterwards though, and it may not start at all. I have had a new battery and glow plugs.
Posted by: roterz

A: Obvious possibilities include: a weak battery giving slow cranking, no or poor voltage supply to the glow plugs, insufficient glow-plug activation time (try applying them three or four times), poor cylinder compression, and an air leak into the fuel supply system.

SPITTING TRUCK
Q: My 1986 Nissan pickup acts like it is flooding: when it idles it speeds up and down, and while driving it spits and sputters. Sometimes though, it runs pretty well. I think it's the carburettor (a throttle-body fuel-injected carburetor) but how to tell for sure?
Posted by: girl_next_door369

A: Either the ignition high-tension circuit is breaking down, or there are one or more air leaks to the carburettor, making the mixture too lean. It'll pay you to have an expert diagnose the problem for you, or you could be fiddling for days with no success.

MYSTERIOUS LINK
Q: I have a 2001 Renault Laguna 1.9dCi on which the speedo has stopped working and the ABS warning light is staying on. Is there any likely connection, and what can be done?
Posted by: stevejinks2763

A: It is possible there's a link between the two, but to be honest, without diagnostic equipment and expertise, there's not much you can do on a DIY basis. Get an auto-electrician to investigate it - promptly.

DIESEL'S LOST ITS PUFF
Q: I have a 1994 Citroen Xantia VSX turbodiesel that feels like it has lost all power. I now have to change down gears to get up hills, even resorting to selecting second on steeper hills. It doesn't seem to be smoking excessively though.
Posted by: weir_stuart

A: If your diesel is out of puff, it may be because (in order of likelihood): the fuel or air filters are clogged, the brakes are binding, the vacuum link between the turbo and the injection pump is disconnected, the valve or injection timing is out (has it had a cam belt change recently?) the throttle cable is incorrectly adjusted, or the turbocharger isn't working (very unlikely!).

A FASCIA IN DARKNESS
Q: The dashboard of my D-reg Golf Cabriolet has gone completely dead - none of the dials work. Is this likely to be a fuse or is it something more serious?
Posted by: tworobinsons

A: It is likely to be something pretty straightforward, such as a multi-connector - probably somewhere behind the dashboard - that has worked loose. There may also be more than one fusebox about the car, so check for another.

VOLTS DOWN THE DRAIN
Q: My Peugeot 309D will not turn over. The dashboard lights are bright until I switch on the glow plugs, at which point they go very dim and nothing happens. Help!
Posted by: 4bonds

A: There's a big power drain going on when you attempt to draw a large load from the battery. Likely suspects are a tired-out battery, and loose or rusty battery terminals or engine earth lead.

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