1994 Dodge 1500 with a 408 I just built this motor and have gone threw 3 thermostats, and replaced the intake gaskets and head gaskets. The heater core, radiator cap have been replaced and still pisses out coolant out of the overflow I'm running out of ideas how to fix it. Or what could be a problem?

 

Is it overheating?? Has it overheated in the past? How long before it starts bubbling out? What's the level look like when it's cold? (there should be a mark on the tank for "Full Cold")

 

I have this similar issue with my 89' Ram, I have it narrowed down to headgasket or plugged radiator... being you did the head gaskets, possibly obstructed radiator? The thing is mine never overheats, atleast thats what the guage says...

 

Yes it over heats less than 10 mins after starting, It didnt over heat on a 25 mile trip, it bubbles when it starts hitting the mid point of the over heating. The level reads full after all is done spitting, then I let it sit over nite then goes to near add

 

Is there the possibility of air still in the system? Could just be vapor locked.....

 

Sounds like its time for a radiator

 

Take the radiator cap off, and start the engine. If it immediately starts bubbling/blowing coolant out the hole, you have a blown head gasket.

 

Well it does bubble out immediately, I have replaced the radiator, and ran the truck w/o the cap on to help rid of air. But I still have alot of pressure in the system. And the oil in the system looks gray

 

Wow. That is a clue. Pull heads. Do you know that the heads are the right ones? Sounds like water jacket is not lining up or blown head gasket or warped head. Either way, heads gotta come back off I think.

 

I would agree with this assessment. You are getting coolant into your oil, which is reeeeallly bad for bearings...... and you are getting cylinder pressure into the cooling system. Either wrong heads for the motor, wrong head gaskets, improper assembly procedure, or the block is cracked.