My PT cruiser,Chrysler hit a top and I fiited a replacement engine,from there on the car started,was driven for test drive,it then overheated and could not start thereon.The mechanic thinks it has to do with the immobilizer which does not switch off.It does turn but the engine could not run

SOURCE: Replacing Alternator For 2001 Chrysler PT Cruiser (Manual)

this instruction is general for all vehicles. i am sorry that i do not have particularly for your 2001 chrysler PT cruiser.

first, identify the alternator.
remove the fan belt on the alternator,
label and remove all wires that is attached to it.
remove all bolts that is holding it.
remove the old alternator.

do the reverse on installing it.

tnx 4 using fixya,

drcool

SOURCE: power steering fluid PT Cruiser

power steering fluid or dextron 3 trans fluid

SOURCE: Crankshaft Position Sensor location 04 PT Cruiser

It is located behind the **** of the starter on the front of the engine starting in '03 the 2.4 lt was changes the repair manual failed to update this..you may sneak it out with small fingers with out pulling out the starter.

SOURCE: 2001 PT Cruiser quit running driving down highway

I HAD THE SAME PROBLEM, I BROKE A TIMING BELT.   HAD TO REPLACE THE ENGINE.

SOURCE: Replacing 2004 PT Cruiser Starter

He can do it. Tell him to just be patient (everything is a tight fit in a PT) and remember to disconnect the battery first. No special tools are required. He may have to move a bracket or two for access. It lives on the left side (front) of the motor and easiest to get to from underneath.