2003 Venture overheated and now running rough

This is my uncles car and Im doing this for him. Its a 2003 Venture that he has had since new. It overheated but there is no water in the oil and there is water in the radiator so Im thinking that the thermostat froze not allowing water to circulate. It runs rough, makes a bit of noise from the top end. Im guessing it bent a valve or ? My question is should I go ahead and take the heads off or just find a good used engine? Im just wondering if the sleeves have been scored due to over heating, if thats the case obviously finding a motor would be the better option but Im not too familiar with these motors so what options would any of you "pros' suggest??? I have located a 3.4 out of a 2003 impala, mileage unknown so I could be getting a bad motor again.
Thanks in advance.

This is my uncles car and Im doing this for him. Its a 2003 Venture that he has had since new. It overheated but there is no water in the oil and there is water in the radiator so Im thinking that the thermostat froze not allowing water to circulate. It runs rough, makes a bit of noise from the top end. Im guessing it bent a valve or ? My question is should I go ahead and take the heads off or just find a good used engine? Im just wondering if the sleeves have been scored due to over heating, if thats the case obviously finding a motor would be the better option but Im not too familiar with these motors so what options would any of you "pros' suggest??? I have located a 3.4 out of a 2003 impala, mileage unknown so I could be getting a bad motor again.
Thanks in advance.

Welcome to AF


Can you make a video of noise and post??? What kind of noise??? A ticking or knock sound??

Do a compression and leak down test before making any hasty decisions.

Have you looked at and tested existing thermostat? Pressure test the cooling system.

Do a detailed diagnoses before throwing monwy at it, diagnoses will save you money in he long run.

Give us as much info as you can.

well, did a leak down test on the motor, #2 cyl is blowing air into the water jackets, not a big deal but #1 cyl there is major lose of pressure and air is being blown into the crankcase so there is damage at least to #1cyl.
Uncle wants this car running so I guess I will be looking for a decent motor...

Found a good motor from an 03 Impala 3.4, is this a good swap for the minivan motor???

Sounds like it overheated and blew a head gasket. Happened to our 01 Venture with the 3.4L engine.

Sounds like it overheated and blew a head gasket. Happened to our 01 Venture with the 3.4L engine.
It definitely blew a head gasket, #2 cyl to be exact. Number 1 cyl is blowing air past the rings into the crankcase with the leakdown test so Im guessing some sleeve damage, pity really, car is in really good shape beside that.