Take it to a mechanic, one that specializes in water damaged cars if you can find them. The list of problems from water damage far exceeds the ability of this site to even begin telling you of the problems you will most likely encounter.
No, it is not. BUT: Starting a car with the exhaust submerged carries other risks. By implication there are other things submerged that could be damaged by water, such as the alternator, HVAC, or transmission. Also, the engine may not start if the starter cannot overcome the water pressure.
There are many car engine damages that could occur to a vehicle from being submerged in water. Your car could short for example.
Normally, they both have the same level of diffiulty, because you're only trying to get out of the car and not out of the water.
You need to warm the car up with hot water.
check and make sure water is not getting in ur alternater cap
How do you know that it is your car?
It wont start
Junk it! It will be a money pit if you try to save it.
Your car wont start. lol
What have you welded ?
use jumpers
ud be looking at a broking t belt plus water pump