is it normal?if yes what is the reason behind this

[sr91]

when car is facing uphill,the engine is turned off and the car is kept in 1st gear(without brakes) so that it wont slide backward.after some time it will go backward for some distance(distance is not large).why does it happens?

[shorod]

Assumptions:
- You're referring to a car with a manual transmission,
- You're not using a parking brake for some reason.

In the scenario you describe, and assuming no parking brake is set, the car is only being held from rolling by a little bit of driveline friction and engine compression. If the engine is small, the compression is somewhat limited, therefore it wouldn't totally surprise me that the engine is able to rotate a bit as compression leaks off. If the engine has a lot of miles on it, it's even more likely as the rings no longer form a great seal against the cylinder walls and valves may have enough carbon build up that they don't fully seal the combustion chamber.

This is one of the reasons it's recommended to turn the front wheels of the car toward a curb when parking on an incline, so that if the car does roll, it will hopefully roll against the curb and stop.

Is there a reason you are not also using the parking brake?

-Rod

[jasongraygits]

Originally Posted by shorod

Assumptions:
- You're referring to a car with a manual transmission,
- You're not using a parking brake for some reason.

In the scenario you describe, and assuming no parking brake is set, the car is only being held from rolling by a little bit of driveline friction and engine compression. If the engine is small, the compression is somewhat limited, therefore it wouldn't totally surprise me that the engine is able to rotate a bit as compression leaks off. If the engine has a lot of miles on it, it's even more likely as the rings no longer form a great seal against the cylinder walls and valves may have enough carbon build up that they don't fully seal the combustion chamber.

This is one of the reasons it's recommended to turn the front wheels of the car toward a curb when parking on an incline, so that if the car does roll, it will hopefully roll against the curb and stop.

Is there a reason you are not also using the parking brake?

-Rod

Best answer i must say. You should have used parking brakes or i rather i should say try to develop a habit of using parking brakes it will help you a lot.

[RidingOnRailz]

Originally Posted by shorod

Assumptions:
- You're referring to a car with a manual transmission,
- You're not using a parking brake for some reason.

In the scenario you describe, and assuming no parking brake is set, the car is only being held from rolling by a little bit of driveline friction and engine compression. If the engine is small, the compression is somewhat limited, therefore it wouldn't totally surprise me that the engine is able to rotate a bit as compression leaks off. If the engine has a lot of miles on it, it's even more likely as the rings no longer form a great seal against the cylinder walls and valves may have enough carbon build up that they don't fully seal the combustion chamber.

This is one of the reasons it's recommended to turn the front wheels of the car toward a curb when parking on an incline, so that if the car does roll, it will hopefully roll against the curb and stop.

Is there a reason you are not also using the parking brake?

-Rod

Third assumption: Is O.P. trying to park the car -
or something else?