I have a 2004 ford expedition with a 4.6 motor. After a tune up it started making a loud noise under the drivers side of the motor. It has been difficult to say the least in finding out where the leak is coming from. I am convinced after doing some research that it is a exhaust manifold leak. What is the best way to find out where exactly the leak is coming from. Thank you for your input

 

Exhaust manifold leaks are generally easier to pinpoint when the engine is cold for two good reasons which are , as parts warm up they tend to expand, but so do cracks, and if you use a piece of hose to reach up under the manifolds you might get a better idea of where it is leaking. You must be careful to keep away from any moving parts and if you do it when cold the chances of getting burned are a little bit less.