CV Raman of Maruti Suzuki answers 23 critical questions for car owners

A1)When we are developing a car, we set the tyre pressure keeping in mind ride comfort, handling performance, fuel efficiency, safety and NVH (Noise, Vibration & Harshness).  As to how the tyre will perform during an emergency is also kept in mind. The tyre pressure recommendation as given by the OEM is very important to follow as far as the customer is concerned. It will give you optimised performance. Driving with low pressure tyres will compromise ride comfort, handling and responsiveness of the car. The vehicle will be sluggish to drive. The vehicle will also deliver a lower fuel efficiency.

Q 2) You drive a car on a long stretch with the right air pressure. Theoretically, the tyres heat up and the air pressure inside increases. WHAT HAPPENS?

A2) There will be absolutely no issue because the tyres will heat up a bit but it will get stabilised as it will get cooled simultaneously because of the wind.  I don’t think there should be a concern here if the ambient temperature is high and the tyre pressure is right. 

Q3) You drive your car with the tyre pressure more than the prescribed limit. WHAT HAPPENS?

A3)  There will be an impact in terms of ride comfort; it will become bumpier and bouncier. The ride will also be a lot harsher. Of course, the handling will improve because the tyre pressure has increased. Sometimes, two separate tyre pressures are given by the manufacturers, depending whether a full load is sitting. The pressures need to be adjusted.  Those are things which are very important for a comfortable journey. It is a way of doing the tuning of the tyres and the suspension for giving this comfort feel to the customers.

Q4) While driving one of the car tyres gets punctured and gets deflated. You insist on driving on. WHAT HAPPENS?

A4) The tyre will get cut and you will hear a lot of noises as it is flattened. In case of front tyre deflation, the driver will be able to immediately make out from the responsiveness of the steering wheel.  And if one continues driving for some period of time, the tyres get cut.

Q5) Can this situation get dangerous?

A5) Yes, in the sense, the control sometimes can become difficult, especially if you are driving at high speeds. If the tyres blow out when you are driving, you do realise the instability in the vehicle. But at medium speeds, one can continue and not feel the difference because of various reasons, for example if the music inside is loud or especially if on rear tyres.

Q6) During dune bashing in SUVs, the tyre pressure is lowered. WHY DO THEY DO THIS? WHAT HAPPENS when you do not lower the tyre pressure while dune bashing?

A6) Since sand is very soft, with the specified tyre pressure, the tyres will start digging into the sand. In order to reduce that, they lower the tyres pressure. It allows you to get the traction on a softer surface. That makes it easier for the vehicle to move around. 

Q7) In a petrol car you fill in diesel fuel by mistake, and vice versa. WHAT HAPPENS?

A7) We do make sure that we put a sticker on the fuel cap, whether it is diesel or petrol. And today in accessories also, we have a full decal which says petrol or diesel which can be put right on top of the fuel lid so that they are very careful. But sometimes there is a mistake by the customer or the guy filling the fuel.

In case diesel is put in petrol car, it will not atomise like petrol resulting in insufficient combustion of fuel,excessive soot generation or misfire, which may lead to engine damage. Conversely, in case petrol is put in diesel engine, the air fuel mixture will not burn as there are no spark plugs and hence will not start. It will operate till the diesel fuel in line is over. Also lubrication of some key parts like High Pressure fuel pump will not happen with Gasoline fuel resulting in permanent damage.

Q8) The coolant / engine oil in your car leaks completely while you are driving. WHAT HAPPENS?

A8) If coolant leaks, it may not show up if there is no coolant in Engine (sensor may be measuring air temperature in the coolant jacket). Customers should be careful, if there is an accident or coolant leakage is observed under the vehicle.  However, if coolant temperature increases for any reason, it will show up on the instrument cluster. If that happens, one needs to take it to the service centre. In case you miss reading the temperature warning it will lead to some kind of stress which can lead to the engine seizing. If there is a loss of lubricant (engine oil) or loss of coolant, the engine could seize.  If the engine oil is lower than low level, it could lead to the engine seizure.

Q9) Can water be substituted for coolant in an emergency situation?

A9) That does work. But the heat removal will be lesser. It can’t be used for long. It could lead to some kind of a seizure of the engine if one continues with it for long. The boiling point will be lower since this is a presurrised system. Heat removal will become an issue. It does have an impact on the thermal efficiency. Using water is also not recommended as it could lead to scaling inside engine causing heat up and slow damage to the engine.

Q10) There is no brake oil and you keep driving. WHAT HAPPENS?

A10) Usually, there is a secondary circuit which is there and even if there is leak on one circuit, we will still be able to stop the vehicle. It should not get impacted. But if both the circuits are completely drained, which is a very unusual situation, and I do not think it will ever happen, at slow speeds you can always stop with the hand brake. If one circuit leaks, then there is a tertiary circuit which will allow the brakes to function.  That’s how the system works.

Q11) While changing a flat tyre onefits the jack in a wrong place under the vehicle body. WHAT HAPPENS?

A11) It’s not a right thing to do, because jacking points are usually specified by the manufacturers in the owner’s manual. It can lead to an imbalance in your jack. The lift up may not happen to the extent where you want the tyre to come out. People should read the owner’s manual and understand that there are jacking point for the front and the rear. And if this is not done properly, it can imbalance the vehicle and this may not be safe. It could also damage the underbody.

Q12) The driver yanks out the car key while driving his vehicle. WHAT HAPPENS?

A12) If you do that, the engine will stop. The first impact is on the braking system because the vacuum will get lost.Steering also will get hard. It is not a very sane thing to do. It is dangerous.

Q13) In a push button start / stop car, you press the button while driving. WHAT HAPPENS?

A13) In the case of push button, if there is an emergency he has to continuously press for two seconds or Press the button three times in order to stop the vehicle. Otherwise it will not respond when the vehicle is moving.

Q14) You are driving at a good speed and suddenly someone pulls the hand brake. WHAT HAPPENS?

A14). The rear wheels are braked and front wheels are at the same speed which causes imbalance and the vehicle can spin.

Q15) You are driving around with your hand brake lever pulled up partially and it is not completely disengaged. WHAT HAPPENS?

A15) If the hand brakes are engaged, it reflects on the instrument cluster. The light for parking brake will come up. If this is still ignored and people keepdriving, you will feel a bit of sluggishness and it will of course impact the friction material of the brake lining. The material will get eroded. This will also cause excessive fuel consumption as you are putting more load on engine.

Q16) You are driving normally and you suddenly try to slot the reverse gear. WHAT HAPPENS?

A16)In a 5 speed gear transmission, normally the reverse is just below the fifth gear. Any deliberate attempt to move to reverse gear from 5th gear is prevented by the mechanical inhibitor system in the transmission.Sometimes such an inhibition is provided in Gear shift lever (usually in 6 speed transmissions) where you have to lift the knob up and push into reverse gear. But if you forcefully try to move from a third or fourth gear to reverse, there will be a loud clashing noise and sudden load increase feeling on the gear knob due to high inertia of reverse gear. You will definitely realize there is something wrong.

Q17) In an automatic transmission car, one tries moving from Drive mode “D”to  Reverse “R”while driving. WHAT HAPPENS?

A17) Automatic transmissions are electronically controlled. While deliberately trying to shift it to “R”, it will not engage in reverse gear, even if the Gear Lever is in R position, till the car comes down to a threshold speed. This speed of reverse gear engagement is normally  less than 10kmph.

Q18) You are driving a manual car with the clutch pedal half depressed. WHAT HAPPENS?

A18) Clutch riding used to be a common issue in the past. But nowadays most customers understand that they do not have to ride the clutch. . Clutch life is severely compromised if the car is continuously driven with half depressed clutch pedal. The customer will also feel loss of power and acceleration.

Q19) It is a warm day and you are in a stationery car with the engine running. You put on the AC and take a nap. WHAT HAPPENS?

A19) It is not recommended. There should be some level of air circulation. The internal air (cabin air) in re-circulating mode can get contaminated and this can lead to suffocation because of lack of oxygen. If at all one does it, they need to lower the windows a little bit so that some fresh air keeps coming in. Or you can put it in fresh mode for fresh air to come in but then the cooling gets impacted. I will not recommend running your ac for a long period in a stationery car with your engine running and your windows rolled up. It has its impact, one definitely from the health perspective, second from the fuel efficiency point.

Q20) Your AC is on and your engine is running. You car is in a closed garage. WHAT HAPPENS?

A20) The situation will be worse. I will definitely not recommend it because it is a closed space. The exhaust is on, the pollutants are getting circulated with the fresh air and that’s worse. This is not at all recommended.

Q21) You are driving your car fitted with air bags, without a seat belt. You meet with a frontal accident and your air bags are deployed. WHAT HAPPENS?

A21) Wearing seat belts help you to reduce injuries during accidents by as much as 55 to 60 per cent. Airbags help you by another 5 to 10 per cent. Without wearing a seat belt, the air bag alone will not help you reduce the severity of the crash. The seat belt is the primary safety mechanism which restrains the occupants. The secondary  system is the air bag which helps in reducing the injury to the occupant. If you are not wearing a seat belt, the impact is going to be very high if the airbag gets deployed.

Similarly, where vehicle manufacturers are concerned, we give seat belts for all five seats in a 5-seater. Generally it is noticed that only people in front wear the seat belts, while at the rear nobody does. I would recommend that everybody should wear a seat belt. If the person in the rear is not wearing a seat belt, he can be thrown in front in the case of an accident. And if the person in front is also not wearing a seat belt, the situation can be really worse. It is generally seen that not wearing a seat belt results in large number of fatalities in road accidents. That can be really prevented if one were to wear seat belts. Of course, the more important thing is driving safely and below recommended speed limits.

Q22) Ankit Bhardwaj: You fit bigger sized tyres in your car, bigger that what is recommended. WHAT HAPPENS?

A22) By fitting bigger sized tyres, you tend to change the offset of the knuckle or where it is fitted. The large / wide tyre will also interfere with the wheel housing. So, when you are turning the vehicle, you will not get the full turn and it will intrude into the wheel housing or clash or rub with the wheel housing.

Q23) Lastly, when you have larger and smarter looking tyres, will it be able to clear the requirements for wheel balancing and wheel alignment?

A23) No, it won’t because the offset is there. When you are putting a larger tyre, what they do is at the knuckle side they will put an additional offset, usually a steel component, to put the tyre out. Most of the times you will get to see these large tyres sticking out of the body. That is because, one, when it is turning you need to create some space in the wheel housing. Two, the kinematics of this is obviously not the desired kinematics, it is different and definitely there will be some issues with that in terms of durability. Fitting larger tyres to your vehicle is more of a fad and it should be avoided.