I overheated and boiled over on the freeway, engine died and wouldn't start, called tow truck to make it home, kicked myself in the |***| I suspected stuck thermostat and changed it out as water pump and short block recently rebuilt. After changing out the thermostat I refilled the coolant, restarted and the engine runs rough with white smoke puffing out the exhaust. Muffler also dripping liquid, coolant I presume. So could it be blown head gasket, the head its self, cracked block or is there something else I should check first. No water in the oil and cant tell if oil in the coolant as it burns off fairly quick. Should I start with a compression check or something else? Any input appreciated.

 

You should start with a compression check. On all cylinders. The compression spec. for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

Get this done and let us know what you find!

Low pressure on two adjacent cylinders would indicate a blown head gasket. Hopefully that is what you'll find and that is all that is damaged.

 

My guess is a blown head gasket. It happened to my old ladies jeep. We changed thermostat and water pump after it over heated twice. Third time was a doosie. Oil in radiator reservoir etc and clogged radiator.

TylerL. 94 ZJ 3" lift. My DD.

 

pull the head plain and simple, according to your symptoms

 

I would agree and check compression first. when you had the short block rebuilt did you have anything done to the head? have it checked or anything. I ran into the same problem with mine and i replaced the head gasket a few times thinking i did something wrong but it ended up being a bad head.

 

Seems like alot if the older jeeps like to overheat. Mine did too. Replaced a good amount. Thought of trying a new radiator cuz it still likes to creep up.

 

Cracked head and/or blown head gasket.

Hope you didn't cook the lower end.