I have a GMC 4x4 with a 5.7. Steam is coming from the tail pipes...more so from the passenger side...also sounds like it is missing on the side. Listening to the engine bay it sounds normal, except for a hint of it missing. We pulled the plugs one at a time and fired it up, but no change and all wires were firing. The plugs were filed bad...like rounded and a significant gap. I decided to turn the engine over with a plug out on the driver side and water shot out like a shotgun blast.

The initial issue was discovered when it ran hot.

What could it be? my suspicion is the head gasket. With the motor not sounding or driving rough (short test drive) i assume the heads are okay. If I am correct how difficult is it to replace (by a knowledgeable family member and myself) or how costly by a mechanic.

Also, will the catalytic converter be ruined by the water?

Thanks for the help!

 

Sounds like a head gasket. It can be a time consuming task but not too bad. Attention to detail!!! I always have my heads inspected and tested by my local automotive machine shop. Money well spent.
Cat conv??? I have never had an issue but that doesn't mean that there wont be.

 

you could check your oil too.. see if is milky.

 

Leaking head gaskets do not always leak water into the crankcase even though it normally does

 

Could be worse than just a head gasket. It could be a cracked head. A good machine shop can test the head for leaks when you remove it.

 

It is your intake gaskets

 

A blown head gasket/cracked head would pressurize the cooling system.Take off the rad cap and wait for the thermostat to open,then check for bubbles in the rad.