Replacing an engine can be very labor intensive on some cars and trucks and can take a few days or even a week to complete the engine swap depending on what needs to be removed to get the engine out and put the new engine in.
You can expect to pay between $500.00 to $1,000.00 for the labor alone to replace the engine in a vehicle.
Then the cost of the engine can be as high as $1,500.00 to $3,000.00 for a brand new engine or even for a rebuilt engine.
So with the engine and the cost of the labor to replace the engine you can expect to pay between $2,000.00 to $4,000.00
Sometimes it might be worth the cost if it's an expensive car or a nice truck that cost you a lot of money and sometimes if it's an older used cheap car then you can usually just buy another used car for the price of the replacement engine.
For example if I spent $50,000.00 on a new truck and eventually it needed a brand new or rebuilt motor then I would have no problem spending another $4,000.00 to replace the motor and a bit more to replace or rebuild the transmission.
I would never get my money back selling my truck I spent $50,000.00 for so by spending the $4,000.00 or so to replace the motor in the truck would keep the truck going down the road like it was new.