Cadillac Repair: 1997 eldorado engine replacement, silicone spray, power steering pump

Question
i had a mechanic install a 1998 eldorado 4.6 liter engine into my 1997 eldorado etc but can't get rid of a loud squeak coming from the serpentine belt which we replaced along with the tension pulley and the power steering pump and the water pump. is this because its not a 1997 engine?

Answer
The year of the engine makes no difference, You have one of the pulleys that run one of the components that the serpentine belt drives out of alignment.

Try spraying some SILICONE SPRAY on the belt to see if the noise gets and less noisy and let me know.