Hello everybody, thank you in advance for any advice or suggestions. I have acquired another X308. It presented to me as needing an alternator otherwise was said to be a running vehicle. I proceed to remove the alternator and test as it is bad I remove the alternator from my other 1998XJ8 and install. Look things over quickly top off the oil and charge The battery. car starts up right away. I should also mention majority of the exhaust is missing. I proceeded to move the car a short distance till I had more time to work on it. When I got back to the vehicle, it appeared as if the battery was dead so I charged again and jumped the car, the car started right away and Idled fine. I’d let the car come up to temperature check heat etc. while the car was sitting running I started to hear a slight rotational sound from the driver side, engine compartment i.e. pulley going bad maybe but it was a faint sound. while I was listening, the engine out of the blue just stops. When I attempted to restart the battery appeared dead again. I should mention that I tested the alternator at the battery when I first started up the car. so I put the jump back on and the motor would still not turn over. I attempt to remove the serpentine belt to check the pulleys but the tensioner would not move. I finally free it up and get the belt off. The tensioner pulley did feel a bit off. The rest of the pulleys were free. I proceeded to put a socket wrench on the crank and found it very hard to turn in my opinion harder than it should be. At this point I proceeded to back out for the evening. At this point I am open to suggestions and or opinions as to what may have happened thank you in advance, I will keep you posted I believe today I will first remove the spark plugs and drop a little oil in each cylinder in attempt to free up the engine. ✌🏻

Maybe it overheated while idling? Let it sit overnight before trying a restart is my advice.

Addicted2boost, I had the same thought however the temp “appeared” ok. This is why I quit for the night and will definitely be checking that here soon. Thanks.

Do not trust the temp gauge. The thermostat may be stuck shut or the water pump may have failed.

When I first started the car, it actually ran for a while. I watched it come up to temp and had great heat inside. Then it held there. Something weird about the motor just coming to a halt with little to no noise?? Not seeing any metal or sludge on the dipstick or anywhere else for that matter 🤷🏻‍♂️