Help.No heat . blows cold air.

[Wesley84mc]

I have an 84 monte Carlo ss with stock 305 . I drive it half of the year or anytime i get the chance. I love it . but this morning I hopped in and my throttle got stuck open because the spring was stuck . I shut it off repositioned the spring and restarted it. Everything was good. I get about a mile down the road and pop the hood and I have coolant boiling out of the overflow and no heat. Last year i replaced the blower motor and wheel and I never had good heat but none the less heat. Right now i think its the thermostat which i replaced last year with the motor and wheel. Could it be the heater core ? Does the coolant boiling over point to anything specific or is it just related to the thermostat . also what thermo should I put in ,160,180,190. Also I posted a pic of a sector gear that broke in the ignition. Does anyone have a part bumber . thanks in advance

 

[fleming442]

Boiling over + no heat = blown head gasket in my brain (comes from a previous experience with a Quad4)

 

[MechMan]

I would say check the thermostat first, easiest and cheapest option. That happened to my fathers Regal. If that isnt it it could very well be a head gasket issue. My wife's Civic would over heat but no big signs of a leak. turned out to have a pin hole leak in the head gasket that when under load exhaust gasses were forced into the coolant and forced it out the overfill. If the thermostat doesnt correct the issue get it pressure tested.

 

[Turbo Zach]

What I would do. After it cools down. Refill the radiator. Stat the engine. Leave the radiator cap off. Watch for bubbles in the radiator while watching the temp. Bubbles= headgasket. 200 degrees and no bubbles = thermostat. Every thing ok and still no heat? Obstruction in heater core or heat valve.

 

[MrSony]

What I would do. After it cools down. Refill the radiator. Stat the engine. Leave the radiator cap off. Watch for bubbles in the radiator while watching the temp. Bubbles= headgasket. 200 degrees and no bubbles = thermostat. Every thing ok and still no heat? Obstruction in heater core or heat valve.

Caution: dont open the rad cap after the engine has been ran or is hot.

 

[Local Hero]

Mine boiled over and no heat on the coldest night of the year last year. It was because the lower radiator hose blew off and I lost all the antifreeze. I managed to blast it home just as the temp gauge pegged beyond 280. I figured I was close enough to home to take the chance vs. sitting on the side of the road in -25*F temps.

Turbo Zach nailed it with diagnosing your issue.

 

[84calelky]

boiling over no heat , check the water pump , impeller might have eroded away .

 

[TURNA]

Sounds like a new dohickie is needed on your thingamabob.

 

[fleming442]

It's yer catastrophic converter, Vern

 

[Wesley84mc]

Thanks all. Luckily it wasnt the head gasket . thermostat was bad and I lost most of my coolant somehow. Filled the radiator on a slope with heat on high and it came out hot as ever . thanks for all the help.