Professional Car Repairman Interview Questions & Answers:

1. Explain what Is The Use Of Hydrogen In Automobile?

Low emissions. Essentially no CO or HC in the exhaust as there is no carbon in the fuel. Most exhaust would be H2O and N2 Fuel availability. There are a number of different ways of making hydrogen, including electrolysis of water.

2. Do you know what Is Back Compressor In Engines?

Back compression means the compression capability of the engine. An diesel engine can compress at the ratio of 14:1 to as high as 25:1. Thus the higher compression leads to better efficiency of the engine. Thick black smoke is emitted when the engine's compression is reduced which leads to the deformed ead-gasket lead into crankcase.

3. Tell us what Is Octane Number And Cetane Number?

Octane number can be defined as the percentage, by volume, of iso-octane in the mixture of iso-octane and h-heptane. It is the measure of rating of SI engine.

While cetane number can be defined as the percentage,by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.

4. Tell me what Will Happen If Someone Adds Oil To The Fuel Of Four Stroke Bike Engine?

This will result in damaging of the engine faster. Adding oil will lead to the higher wear and tear of the cylinder liner, piston and damage to the piston. It will lead to abnormal combustion and knocking and detonation. Dark smoke and abnormal sounds will be generated by the engine. One should not mix oil with the fuel of four stroke engine.

5. Tell us what Is Pitching In The Suspension System?

Pitching is a rocking action about a transverse axis through the vehicle, parallel to the ground. The front suspension moves out of phase with the rear, experiencing the rocking effect due to pitching.

6. Do you know how Does The Thermostat Work?

When the engine is too cold the thermostat closes the main valve, thus stopping the flow to the radiator. When the engine is too hot, it opens the main valve for normal circulation through the radiator.

7. Do you know what Is Bhp? How Can You Measure Bhp?

BHP is ‘Brake Horsepower'. It reflects the powerfulness of the brakes of the vehicles. BHP stands for how much power will be required to make the engine stop working i.e. to stop the rotation of the engine.

BHP = 2 times pi times torque times revolutions; all this divided by 550. Pi is 3.1416 and torque is in pounds-feet, and revolutions are revs per second.

8. Tell me what Do You Mean By Independent Suspension?

Independent suspension refers to the mounting of the wheel on a separate axle, so that road shocks affect only the particular wheel.

9. Tell me does Diesel Engine Powered Automobile Use Unit Pump And Unit Injector?

In the case of the engines powered by diesel fuel supply systems, unit pump & unit injector are operated by camshaft & thus pressure of injected fuel depends on engine speed. Whereas,in common rail systems it is independent of engine speed.

10. Tell us why Does A Compression Engine Use High –octane Fuel?

The property of a fuel, which describes how fuel will or will not self-ignite, is called the octane number or just octane. Engines with low compression ratios can use fuels with lower octane number, but high compression engines must use high-octane fuels to avoid self-ignition and knock.