Originally Posted by Swapnil
My guess -
1. There is a big leak somewhere.
2. The belt is loose.
If you lost that much fluid in such a short interval, there is a big leak somewhere in the power steering system which would be very easy to track. This could also be a leak from the seals in the rack itself, but the way you have described the problem it sounds more like a power steering hose is leaking somewhere in the system.
First of all, we can start with few simple diagnostics related to reservoir and pump. Did you ever notice any fluid on the ground under the engine bay after you have have parked the car over night? It would be helpful to spot the right place of leak if there is some fluid on the ground.
The hydraulic seals in the power steering pump can fail, but if that is the case you should have difficulty in turning steering wheel. But when you filled the reservoir again, the steering functioning was back to normal so we can rule out the power steering pump. Between, never drive the car with no power steering fluid. It can damage the pump in very little time by overheating, causing seizure of the pulley and engine lockup in the worst cases. There are no vane type pumps designed to run without power steering fluid and whoever suggesting you it as okay is totally wrong.
Since we ruled out the PS pump, next easier thing would be the reservoir. The reservoir is just there to hold the fluid in the system and deliver it whenever needed. The reservoir seldom goes bad unless it is made by cheap plastic which can crack by age. The main leak area near the reservoir is where the two rubber hoses are attached to it. These hoses can crack with heat/age and can cause major leaks. These hoses are connected to the reservoir housing using worm clamps which can also damage the hoses if they were over tightened originally. So check underneath the reservoir and see whether there is any visible leakage in the pump-to-hose joints.
If you don't see any visible leaks above, then you have to check all the hoses in the system which will be little difficult. It depends on how much space you have in the engine bay and how these hoses are routed. I see in google that Indigo has got a transverse mounted engine, which makes it little difficult to trace these hoses. Before checking hoses, you would have to jack up the front end of the car(use two jacks on both sides or one floor jack)and turn the steering wheel from lock-to-lock(fully left and then fully right...) five or six times. Make sure you have power steering fluid in the reservoir to the marked level before doing this. By doing this, fluid will circulate through the whole system and if there is any leak somewhere we should be able to visually identify it.
One of the hose from the reservoir goes to the power steering pump. Inspect that hose for any leaks throughout its route. Look for leaks at the end where the hose meets the power steering pump. The other hose from the reservoir goes to the steering rack which will be a little difficult to see from the top if the rack is sitting too low. It would be better if you could locate the position of steering rack in your car at this point. There is one more hose in the system that goes from the steering pump into the steering rack which is commonly called as power steering pressure hose line. This hose is notorious for developing big leaks in the system with age/ miles. If you have not spotted any leaks in the system so far with the above checks, then the chances are very high that this power steering pressure hose is leaking. The fluid in this hose is always under high pressure than any other hose in the system and may develop leaks near to its ends in the long run. Check for leaks near the ends where the hose meets meets the pump and the rack. Unlike other hoses, this hose should be attached to the pump and rack using metal bolts and it would be easy to identify.
If you have not found anything yet, then the last thing remaining in the system is the power steering rack which is a pain in the ass
to replace in most of the cars. The rack has got seals in it which may fail causing leakage of fluid. But the way your car lost fluid, I believe the leak is not in the rack.
These are some of the things you can check by your own. It is always better to know what's happening in your car before taking it to a mechanic. A mechanic works for money, so you know..........right?