I have been looking for a Mazda3 for a while to use as a daily driver and found one close to me. It's a 2006 auto with a 2.3 4 cyl. Only thing is the guy says that the engine has a rod knocking and needs to be rebuilt or replaced. The car has less than 82,000 on it. Would it be better (and cheaper) to rebuild the existing engine or swap out with another? I would not be doing this myself as I have no idea how to do either so it would be off to the local shop. Also, any guesstimate on what each would cost?

 

Your best answer would need to either be from someone that lives in your state (PA) or you need to find yourself.
I would look online and local for low mileage engines with w warranty. Then contact local shops and ask about swapping out the engines. remember that there will be other parts that may and should be replaced at the time of the swap. You can also look in craigs list for mobile mechanics.
As for the cost of rebuilding the existing one it would likely cost more than what I mentioned earlier but you can get estimate by calling local Engine Machine Shops.

After you get all the estimate then you can balance the worth of the car vs the cost to get it up and running reliably.