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AUTO BILD INDIA shows you how to recognise problems by their distinctive odours
Although the human nose is not as able as those of other mammals when it comes to smells, it is still capable of detecting several thousand different types of odours. But what does the human nose have to do with a car? An automotive problem can hardly be sniffed out. Or can it?
Think again, for some car problems do have specific odours. So, incredibly enough, you can indeed utilise your sense of smell to diagnose some car problems as and when they crop up.
Here is a list of 10 odours that might help you pin point what is probably wrong with your beloved vehicle.
After the engine has warmed up or possibly even after it's shut off for a few minutes, you might notice a sweet syrupy smell in your car. Your coolant containing a sweet-smelling (but toxic) ethylene glycol, is probably leaking. The leak could be from a radiator or heater hose, a failed intake gasket or cylinder head. It could be coming from a leaky radiator cap or the radiator itself, especially if you smell it outside the car. A strong odour inside the passenger compartment could mean a bad heater core. You could have a blown head gasket, which causes coolant to mix with your fuel. If this is the case, you may notice thick, sweetsmelling, whitish smoke coming from the exhaust. Contact your mechanic immediately.
The smell of rotten eggs could indicate a plugged or damaged catalytic converter or too rich an air:fuel mixture. The smell of rotten eggs is actually Hydrogen Sulphide gas in the exhaust, which is produced by trace amounts of Sulphur in petrol. It's supposed to be converted to Sulphur Dioxide in your catalytic converter. This effect is noticeable if the engine suddenly starts to run a rich mixture with not enough air to burn all the fuel, such as when you stop at a red light, climb a steep hill, or brake hard to slow down. This may be indicative of a fuel-injection problem or it means a failing catalytic converter.
A burnt toast smell could mean the electrical insulation is burning. If the car starts to smell of burnt toast, the reason is mostly caused by overheated electrical wiring. Wire overheating once discovered must immediately be investigated into, to fi nd out the reasons for the smell. The risk factor is very high and generally occurs in the summer months when ambient temperatures are high. In such cases even a loose connection could lead to sparks and if left unattended, it could easily damage the circuit completely, or even lead to a spontaneous combustion of the vehicle.
Sometimes you might get a strong smell of fuel in the car when the vehicle is parked, especially inside a garage or when the weather is really warm. On older carburetted cars, some odour after a hot shutoff is normal from fuel after-boil in the carburettor float bowl. If you have just attempted to start the car and failed a few times, it could just be that the engine is "flooded" with petrol. Modern cars have an evaporative emissions system that's tighter, so any fuel smell means something is wrong. There may be a leak from a fuel-injection line or a fuel-tank vent hose. It could be a loose fuel cap or even an overfi lled fuel tank. If neither of these happened, then don’t risk starting the engine as you may have a severed fuel line or a leaky fuelinjection system. The raw petrol smell could also be from the exhaust pipe due to over rich fuel mixture condition.
Gear lubricants are designed to reduce friction and wear, act as heat transfer agents, and protect against corrosion and rust. They may contain active Sulphur to provide a thermally stable, non-corrosive lubricant with high load-carrying capacity. If your car interior starts smelling like Sulphur, then it could be gear lubricant leaking from the transmission. Look for sulphury-smelling, oily stuff under the car.
This may be as simple as a plastic bag caught under the car and which is slowly melting and giving off the odour. Check the underbody and also the engine compartment. If that’s the case, you’ll probably just have to wait for the plastic to burn off or the car to cool down before you remove the plastic remains.
You turn on the air-conditioner fan and you get a whiff of what smells like a sweaty pair of socks. The reason, is probably the growth of mildew in the AC, courtesy the moisture condensing inside the AC evaporator. Turn off the air con a kilometre or so from home and run the fan on high to dry the system out. If the smell is just stale without the bad odour, then it's just water condensation. When the AC is on, water condensation develops and settles in the evaporator core housing. Again run the fan only to dry the system out.
If there is a smell of hot oil when the engine is heated up, the reason could be oil leaking onto the hot exhaust. The smell is an acrid, burning smell which is earthier and more nose-wrinkling than the odour of hot used cooking oil. If it's from a leaky crankshaft seal that's spraying oil all over, you will fi nd some of it on the hot exhaust but most will be on the pavement. A leaky valve cover won't necessarily leave a drip on the floor if all the oil dribbles onto the exhaust, vapourising immediately. Look for smoke emanating from the exhaust.
A rubber hose may be resting on the exhaust assembly, or a belt may be shredded by a jammed pulley. If a belt is loose or worn, it is usually indicated by a squeal. Turn off your engine and inspect the hoses and belts and replace as necessary. After you've been using the brakes a lot, or hard, or a mix of both, the brake pads get overheated and the odour might seem like the smell of burnt carpets. This is perfectly normal after riding the brakes coming down a steep mountain with lots of braking to retard your descent. In these situations if you downshift and use engine braking instead of brakes, then you will avoid the smells and save your brake pads too. If you smell this under normal driving conditions, either you've got a dragging brake or you just left the handbrake on.
The burnt paper smell is noticeable at all speeds, particularly when you're working your way through the gears a lot or if you habitually ride the clutch. The reason being that the clutch plate, which is in contact, is getting burnt off as the clutch slips. The odour will remind you of burning newspaper. The friction material on the clutch plate is actually made up of paper composition, which explains the papery part of the smell. Either get the clutch replaced immediately or stop riding the clutch.
