# Over heating

**URL:** <https://community.cartalk.com/t/over-heating/42100>\
**Category:** Maintenance/Repairs\
**Tags:** chevrolet, impala\
**Created:** [January 9, 2010, 12:57am UTC](https://community.cartalk.com/t/over-heating/42100 "2010-01-09T00:57:15Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![0Paul0](https://avatars.discourse-cdn.com/v4/letter/0/df705f/32.png) [@0Paul0](https://community.cartalk.com/u/0Paul0)\
**Post date:** [January 9, 2010, 12:57am UTC](https://community.cartalk.com/t/over-heating/42100/1 "2010-01-09T00:57:15Z")

</div>

I have a 2002 impala with a 3.4 lt  
  
 the temp runs fine until i turn on the heater then the the car tends to over heat but i only get cold air from the fan.

---

<div class="post-metadata">

**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\
**Post date:** [January 9, 2010, 1:53am UTC](https://community.cartalk.com/t/over-heating/42100/2 "2010-01-09T01:53:43Z")

</div>

Sounds like you have low coolant level, try refilling with 50-50 antifreeze. If that fixes it keep an eye on the level, you could have a leak.

---

<div class="post-metadata">

**Author:** ![geeaea](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@geeaea](https://community.cartalk.com/u/geeaea)\
**Post date:** [January 9, 2010, 2:07am UTC](https://community.cartalk.com/t/over-heating/42100/3 "2010-01-09T02:07:32Z")

</div>

That would be my first place to look. Oddly, it should produce hot air except at idle …but that depends on how far low it is. One would reason that you probably use the heater core as the bypass hose (most cars) and that the heater would only act as an additional radiator. It may not be the case with your installation.

---

<div class="post-metadata">

**Author:** ![0Paul0](https://avatars.discourse-cdn.com/v4/letter/0/df705f/32.png) [@0Paul0](https://community.cartalk.com/u/0Paul0)\
**Post date:** [January 20, 2010, 1:00am UTC](https://community.cartalk.com/t/over-heating/42100/4 "2010-01-20T01:00:33Z")

</div>

I flushed the radiator,replaced the radiator cap,replaced the thermostat,and replaced the water pump and did a presure test and still having the same problem.

---

<div class="post-metadata">

**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [January 20, 2010, 1:47am UTC](https://community.cartalk.com/t/over-heating/42100/5 "2010-01-20T01:47:42Z")

</div>

Try this.

Get the engine up to operating temperature. With the engine idling loosen the upper radiator hose clamp. Take a small flat bladed screwdriver and slip it between the upper radiator hose and the radiator hose neck. Allow the engine to continue to idle until a steady stream of coolant comes out of the radiator hose. Remove the screwdriver and retighten the hose clamp.

Tester

---

<div class="post-metadata">

**Author:** ![geeaea](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@geeaea](https://community.cartalk.com/u/geeaea)\
**Post date:** [January 20, 2010, 1:49am UTC](https://community.cartalk.com/t/over-heating/42100/6 "2010-01-20T01:49:08Z")

</div>

Can you give us the event train? Have you switched on the heater …experienced the increase in temp …shut it down …restarted …repeated? I somehow can’t see this not burping itself. Some are more difficult than others.

Get a longer piece of heater hose. Break it mid-span (by a mender and clamps before hand). With the engine COLD, fill the engine with coolant mix through the hose. Eventually the coolant will pour out of the other end of the hose. You’ll be holding this above the highest level that the coolant will ever see while sealed …well above the heater core …well above the intake …well above the radiator.

Mate, clamp, start. This is somewhat draconian, but you need to eliminate any air that may be trapped in the engine. This is the only way I can describe that will 100% assure that you get it correct.

Good luck.
