boiling coolant

**BlackGT97** · 09-01-2011

about 2 weeks ago i replaced the coolant elbow (1997). never seen/heard boiling coolant prior or up to today. it was boiling for like ten minutes straght. the car never "overheated" but was running hot.

im thinking new t stat, maybe coolant sensor, and flush. should i try something else? and i did bleed the system several times.

yes i did to some searching lol

**Fivefingerdeathpunch** · 09-01-2011

did you bleed the cooling system to get rid of the air in it?

**BlackGT97** · 09-01-2011

yes, sorry just added it to op

**QUICKSILVER462** · 09-01-2011

Boiling means there is a pressure loss of the cooling system. Did you check your radiator cap? You did not mention the radiator cap in your first post.
A 15 psi cap and 50/50 coolant water mix should not boil until 250f, therefor if
you did not loose pressure and you were boiling, you WERE very HOT.
You stated you replaced a coolant elbow, was that the source of your pressure loss?

**BlackGT97** · 09-01-2011

it was leaking so i replaced it. its mostly pure water in there, but it should NEVER boil. no more leaks after elbow replacement. its been fine for the past 2 weeks.

what temp does the fans kick on normally? mine kick on just over 210. could the coolant sensor be the source of problem?

**PurpleGuy** · 09-01-2011

Quicksilver said the same thing i was gonna say....radiator cap. But your coolant boiling is a result of pressure loss as the others said. Things to check would the radiator hoses, thermostat housing gasket. Look in the valleys of the lower intake for coolant. If there is some then you're probably loosing pressure. It may be time for LIM gaskets too. I just did them last weekend and my car stopped overheating.

**BlackGT97** · 09-01-2011

so, its not the tstat because the car isnt overheating right? so if theres a leak its sucking in air causing it to boil?

**PurpleGuy** · 09-01-2011

If the car is NOT overheating then i would say it's probably not the tstat. But it never hurts to change it.

**BlackGT97** · 09-01-2011

further information and another question.

after it sit for a minute, i heard it feed into the resevour (obviously from radiator) so can we eliminate something being plugged.

i was also reading that it can boil in the resevoir because its not pressureizzed, this true or not?

**PurpleGuy** · 09-01-2011

I would say true. The only reason that it doesn't boil in the radiator and the rest of the cooling system is because it's under pressure. This is why it's perfectly fine at over 200 degrees but as soon as you pop the cap off (don't) it will come shootin out and boil.

I never understood it at first until one day I put a bottled Mtn. Dew in the freezer. It was cold as hell but not frozen, because it was under pressure. I popped open the cap and I watched the whole thing turn to slush. Top to bottom. Kind of cool actually.

**BlackGT97** · 09-01-2011

i guess there was 2 questions lol. can we eliminate something being plugged?

and thanks for the help guys. it saves alot of timing guessing and checking.

**PurpleGuy** · 09-01-2011

Mmm...not completely. In fact it feeding into the resevoir could actually indicate that something is plugged. Could be the heater core. I don't know if they're a problem on these cars but I know they can get plugged.

What I would do is the coolant flush like you said. And add some coolant flush stuff. I got Peak( I think) but have yet to put it in.

**BlackGT97** · 09-01-2011

kind of a rookie question, but can i take off the upper rad hose and put my water hose in the radiator and let water pump through the system?

**PurpleGuy** · 09-01-2011

You could ya. You could take the thermostat out and try to run water through the system and see if it will come out of the lower rad hose. Might have to remove the belt though so that the water pump can spin.