Car Mechanic - your answers 28/7/2008

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NO GO ROVER 416
Q: After short trips my 1993 Rover 416 SLi (the model with the black rocker cover) refuses to re-start. I have to wait up to 10 minutes before it will co-operate and it's now becoming embarrassing at petrol stations, etc. I’m told that the problem may be the 'fuel sensor'. Posted by: Russell Smith

A: Possible causes of this trouble could be an ailing crankshaft sensor, or the fuel injection relay housed within the ‘Multi Function Unit’ (this is a sealed box containing four sets of relay contacts). Electronic diagnosis at a garage or automotive electronics specialist should precisely and rapidly confirm which components are breaking down.

CLUTCH-EATING ESCORT
Q: My wife's 1988 Ford Escort Convertible is 'eating' clutches, and it's not because of the way she drives... I have changed the clutch cable, self-adjusting quadrant, full pedal box and even the gearbox. After all this work the clutch still starts slipping again after 50-100 miles. After about 120 miles the clutch driven plate is completely burnt out and worn down to the rivets. When it starts to slip the brakes also seem to bind; if left for a couple of hours all is free again. Nobody seems to have an answer to this unusual problem. Posted by: Mark

A: It sounds as if binding brakes may well be at the heart of the problem. While driving, pressure could be building up within the brake system and causing the brakes to be applied (excessive fuel consumption will be another clue to the brakes binding). One possible cause of this could be a flexible brake hose collapsing internally, so that after the brakes are applied by the driver the fluid cannot return quickly enough through the pipe, so the brakes are held 'on' all the time (until when the car is stopped the pressure gradually falls). Check the flexible hoses; sometimes they look okay even when internal collapse has occurred.

CLANKING LAGUNA
Q: The power steering on my Renault Laguna has just failed. Several clanking noises later the engine began to show signs of overheating. What will the problem be and is it likely to entail a costly repair? Posted by: Andrew Wadsley

A: First, check the state of the engine ancillary drive belt(s); a loose, damaged or broken belt will cause the symptoms you describe. If the belt(s) on your Renault is/are obviously ailing, fit new and try the car again. If the problem is just due to the drive belt (hopefully it will be), it shouldn't be costly to fix. However, it would be advisable to have the power steering and cooling systems checked as well, to ensure that there are not deeper problems. It should not be costly to get an opinion from a professional (although if more serious problems are found, of course the rectification costs will be higher). DO NOT drive the car with the engine overheating or more expensive damage will be caused.

. NOT SO COOL AIR CONDITIONING
Q: How do I check the air conditioning coolant level in my Renault Grand Espace? There is no difference in temperature whether the A/C button is engaged or not, even when set to 16 degrees. The A/C light illuminates, so I can only think it must be the coolant level in the air conditioning unit. All other functions seem fine (fan, etc.). Posted by: Chris

A: There is no coolant as such in the air conditioning unit, but it does incorporate a refrigerant system, and this may need to be checked and 're-gassed' by a Renault dealer or a vehicle air conditioning specialist. (If the system is operating normally the air conditioning clutch should engage when the A/C button is pressed; if this isn't happening we advise seeking professional assistance.).

AILING ZAFIRA
Q: I recently had the injector seals replaced on my 2004 Vauxhall Zafira, and since then quite often the vehicle refuses to start, and it has been using oil. There don't appear to be any leaks and there is no smoking. No fault have shown up on the numerous test machines it's been connected to, and now they say it's the turbo. Posted by: F. Smith

A: It is first necessary to establish whether fuel is returning to the tank when the vehicle is not running; the return circuit needs to be tested to see whether it holds vacuum (if not this could cause the problem you describe).

JUDDERY ASTRA
Q: My 'M' registered, petrol-powered Vauxhall Astra is really 'juddery' when driving; this just started today and the 'engine' light came on. Posted by: Sam

A: The juddering is the result of a misfire; the cause of the problem will almost certainly be stored in the car's engine management system computer by way of a ‘fault code’ which will identify the source of the trouble. The car needs to be taken to an automotive diagnostic centre or garage, where its management system will be 'interrogated' by a diagnostic machine which will highlight the relevant fault code. The appropriate components can then be changed to cure the trouble.

HOT MITSUBISHI
Q: My Mitsubishi L200 runs hot every time I drive at over 50 mph. At a garage they have replaced the thermostat and also the turbo (it's killing my pocket) but the vehicle still overheats and the garage doesn't know what the problem is. Can you help? Posted by: Dom Goldsack

A: Almost certainly the problem is due to lack of coolant circulation through the cooling system.

It is possible that the fault may lie with the water pump, but it is more likely that the radiator is silted up internally, or possibly a radiator hose may have collapsed internally (check the hoses first). After a run, but with the engine STOPPED, and keeping your hands and face clear of the cooling fan, feel by hand the centre section of the radiator (TAKE CARE – IT MAY BE HOT!!); if it is cooler than the outer edges, this indicates silting within the centre of the radiator. In any event now have the radiator checked by specialists, and if necessary renew it or have it re-cored. Have the water pump checked too, just in case this is at the end of its life.

. SQUEAKING POLO
Q: I have a 2006 VW Polo. This morning after setting off for work the car started making a squealing noise (like squeaky brakes but continual), which sounded as if it was possibly coming from the rear of the car. As I started back to the house the car made a clunking sound and then the noise was gone. Do you have any idea what could cause this and is it worth taking it in to the garage? Posted by: Sarah

A: Definitely the car needs to be fully checked before being driven. It is difficult to diagnose a noise like this without hearing/seeing the vehicle, but it sounds as if the problem might well be brake-related; possibly a return spring has come loose within the rear brakes. Alternatively it could be that a twig (or similar) has been jammed between the car and a wheel or tyre, making the noise you describe. First, have a look under the vehicle to see if there is anything obvious adrift. If nothing untoward is visible, have the car fully checked (especially the brake system) before driving. it.

FAULTY BEETLE
Q: I recently bought a 1999 used VW New Beetle that had 94K miles on it. Thought it was a good deal till my son drove home his new car and noticed a 'check engine' light and the speedometer stopped working; in addition the air conditioner wasn't blowing cold air, and the mileage recorder was not advancing or working at all. The next day I took it to a diagnostic centre and they found several codes popped up – around 12-14 YIKES! Should the dealer be liable to fix these even though the car was traded in a day earlier but I don't think it was checked out? Should I see if they fix it or just turn it back over to them? Some of them look serious and expensive to fix. I am stopping my cheque payment to the dealer. Please advise. The car runs pretty good. If all this was wrong with the throttle control; fuel injectors (all 4 showing errors); EVAP control system; misfires in cylinders; etc.; shouldn't I not be able to drive it at all and it be jerking or something? Posted by: Tina Ciulla

A: The dealer should be able to fix all the problems you mention (or have them fixed elsewhere) and if you like the car a lot this may be fine, PROVIDED THAT they really do sort out all the troubles. You may prefer to get your money back and start over with another car (and possibly another dealer!). Modern cars will often run seemingly okay with fault codes showing up, but it is unwise to drive very far until the faults are rectified (and in some cases further expensive damage can be caused by doing so). Of course if all these fault codes were showing, it's possible that the previous owner got rid of the vehicle because of them, before having to pay out for the repairs.

VOLVO BLACK SMOKE
Q: Today we were driving on the motorway in our Volvo V40 (petrol engine, year 2000), and we noticed black smoke coming from the exhaust every time my husband accelerated. We drove the car back through the town and there wasn't any black smoke at all. The car was serviced in April and all was fine; it seems to be running okay apart from the smoke. Posted by: Jackie

A: Black smoke is usually a sign that the fuel mixture is over-rich, as opposed to ‘blue’ smoke which indicates that engine oil is being burnt. In any event first check the engine oil level to make sure that the level is correct, and that it hasn’t dropped suddenly (have you noticed oil consumption increasing lately, indicating a possible mechanical problem in the engine?). If all appears to be well in this respect, have the car checked by a garage or diagnostic specialist, especially with regard to fuel mixture. If the car is using more fuel than usual, this is a sign that the mixture is too rich.

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