so as I said before the 96 1500 5.9 sat for almost a year before I got her. I filled up the radiator last night, this morning I overlooked it no leaks. fired it up with thin 5 minutes the temp gauge showed it wads about 230 degrees so I shut it off, turned the key to ignition position and within 15 seconds the gauge showed almost 130 degrees like 150 it was at. I opened the radiator cap, it had a lot of pressure but water was cold. could the thermostat be doing this issue or would the temp sender be bad and messing with me?

 

Feel the hoses, are they hot? If you have pressure, with cold coolant...... you may have bigger problems.

 

Just started the engine again. Took it longer to show overheat but as soon as it did I shut it down. Both hoses and radiator cap cold

 

Does the system have pressure on it? If it does....... I would be tempted to let it completely cool, start it up, and see if the hoses get hard immediately. If they do, that indicates a blown head gasket.

 

Took off the cap the water spewed out under pressure but was ice cold. I have a coolant compression tester I'll check it at lunch

 

just did the compression gas test on radiator. the liquid in the tester stayed blue until the radiator build up pressure and it suck some water in so that means engine is sealed tight

 

If you haven't burped the cooling system yet, it's possible that there is an air pocket under the thermostat, so, the engine temp will get kinda stupid before the 'stat actually opens, and releases the air........ Let it idle, and watch the gauge...... see if things mellow out once the 'stat actually opens once.

 

I could feel it burping in the hoses. im probally just gonna pull the thermostat and run it temp. just to completely check the engine to make sure its good. I live in Houston tx anyway lol

 

Drill a small hole in the t stat! This will allow air from getting trapped and causing issues. Read post #14
https://dodgeforum.com/forum/2nd-gen...p-bleed-2.html

 

so I fired up the ole girl and had my scanner on it viewing the live datastream. watching the ect pid, it got to 220 so I reved it to 2k and watched it drop it and stay at between 170 and 176 so I narrowed it down to bad thermostat or air in system