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Hello and welcome to just answer Jeep. Here is the information from the factory service manual for determining the build date of your 4.0L engine. From the # XXXXX provided, it looks as though this came out of a 1994 Jeep that is a 4.0L, built on September the 9th.
Hope this information is helpful, and let me know if you need more assistance with this.
The 4.0 Liter (242 CID) six-cylinder engine is an In-line, lightweight, overhead valve engine. This engine is designed for unleaded fuel.
The engine cylinder head has dual quench-type combustion chambers that create turbulence and fast burning of the air/fuel mixture. This results in better fuel economy.
The cylinders are numbered 1 through 6 from front to rear. The firing order is 1-5-3-6-2-4 (Engine Firing Order).
The crankshaft rotation is clockwise, when viewed from the front of the engine. The crankshaft rotates within seven main bearings. The camshaft rotates within four bearings.
The engine Build Date Code is located on a machined surface on the right side of the cylinder block between the No.2 and No.3 cylinders (Build Date Code Location).
The digits of the code identify:
No problem I will be here if you need more help. Compression test readings should be around 140 to 150 PSI and each cylinder should be within 25 lbs of each other. If the readings are quite a bit lower than these specs, then suspect ring or valve problems. If they are a lot higher, than suspect carbon build up issues. The 4.0L is a very tough engine, and if it was maintained well should be good for well over 200,000 miles! My wife and I had a 1991 Cherokee a few years ago and it had 247,000 miles on it and was still running great when I sold it.
You are very welcome, and thank you for the accept! If you need more help with this please let me know,