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Anyone know why my heat is all screwed up?

needurhelp1010needurhelp1010 Niagara FallsPosts: 5
edited December 2018 in Chevrolet
Hi everyone I just found this forum. I have a 2006 Impala LT 3.5L with the standard bells and whistles. I bought it used about 2 years ago for just under $4000 CAN. It's a great car! I just have a little problem with my heat and I'll run the whole scenario by you, maybe you can help. Money's tight right now :)
It was probably in August when we were driving and I looked down to see the engine temp through the roof. I immediately pulled over and shut her down. There was no way I was going to check the rad so I checked the overflow which was empty. I filled it with plain water and eventually got back on the road with no ill-effects WHEW! So...when it came time to winterize my car, I did the proper burping of the cooling system and I added 100% anti-freeze to compensate. I took a hydrometer and it says I've got way to much antifreeze than the recommended 50/50 mix. Now since then, it has gotten colder up here in the north. When I start the car I never turn on the heat unless the windows are fogged up. I understand the engine has to be able to provide enough heat. In the past though, the temp would start to rise and you'd at least get an indication of the engine temp from the blower. I get Air Conditioning until the temp gauge reaches half-way. Then everything is good. But at an idle, the heat dissipates to almost cool. If I increase the rpm to over 1000 then it's like a sauna! Go figure. I'd appreciate any feedback. I'm sure this would cost big at the garage!

Best Answers

  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Accepted Answer
    You might have a thermostat problem. If the thermostat is stuck open, you would get those exact symptoms, because the open thermostat allows full circulation when it should actually be cutting it off during initial warm-up.

    If the thermostat tests okay, you might consider a different range of thermostat, most suitable to very cold weather (takes longer to open).
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Accepted Answer
    Possibly. Stop Leak is generally not a good idea unless there is an emergency and you have no choice but to try it. The whole point of Stop Leak is to clog things up!
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,600
    Accepted Answer
    In some of the 3800 V6 engines, a lack of heat out of the heater when the gauge showed the engine temp was running in normal range was a sign of an air pocket (or a partially blocked heater core due to DexCool having been mixed with a standard green coolant possibly).

    When the engine would rev up, the pressure from the water pump pushed more water through the heater and got heat into the metal despite the air.

    For the 3800 there was a procedure in the FSM for burping. You said you have burped the engine, but this recommended revving the engine at 2500 rpm for 15 seconds then idling, then repeating 4 more times. This was after the engine was at normal stable temperature and thermostat open. I usually helped mine by parking uphill in my driveway which has some slope. That put the radiator above the heater core, making it easier to get the air out of the heater with the pressure of the high rev coolant.

    Are there techniques for burping the 3.5?

    Does it have a radiator cap on the actual radiator? If so, open there and have someone rev the engine and fill there while revs are up and put the cap on before the revs are slowed to normal. That was used with the 3800's.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Accepted Answer
    No it can't harm anything in most cases unless perhaps you tried to use pure antifreeze in a very hot climate. Mixing with water increases heat dissipation, and really, pure antifreeze doesn't lower the freeze point very much when compared to a water mix. So you really wouldn't gain anything by using pure antifreeze except perhaps a bit more corrosion protection. Some engineers say that a 70-30 mix of antifreeze to water would be optimum, but most people go with 50-50.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,600
    Accepted Answer
    The mixture of antifreeze and water is an azeotropic mixture. So the best lowest freezing protection is a mixture of the two as the chart shows.



    I reread your symptoms and I realize now you should change the thermostat since you have no idea of the history of the car. You're saying the heater stays cool until the engine has run a long time and heated up all the coolant, radiator, engine together. Then you start getting heat.

    When you start the car and it's cold, the heater hoses should be the first to warm up as the pump circulates the coolant with a closed thermostat. The hose to the upper radiator should stay cool. Then when the thermostat starts to open slightly and wiggle its way open more as the engine heats, the upper radiator hose should have warm water going to the radiator.

    Try feeling the heater hoses after you change the thermostat. Follow how the heat starts through them first. I'd suggest having the blower on low or OFF. Then when both the heater hoses are hot, turn the blower motor on high. The outlet hose from the heater should cool down some since the heat from the water has been extracted by the air over the heater core. Then lower the blower motor back to low and see if the temperature on outlet comes up after a few moments.

    Then try speeding up the engine to 2000 or so to push harder on the coolant through the heater core. If that helps make the outlet get lots hotter, I'd suggest your heater core may be partially blocked. Since the car's history is unknown, when you got it was the coolant in the reserve tank clear orange like normal DexCool?

    Or was the color including murky brown sludge. If someone mixed the wrong antifreeze in, the DexCool can be damaged and the sludge forms. People with 3800s were not real successful with using cleaning chemcals to get rid of sludge. They backflushed the heater core taking the hoses off to gently push water backwards through it. But often bits of sludge would block the tiny passages with only some coolant flow.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

Answers

  • needurhelp1010needurhelp1010 Niagara FallsPosts: 5
    I was just thinking about that. Thanks! I forgot to mention I put a stop-leak product in the cooling system just before this all started, because the level was low. I'm wondering if it might have clogged the thermostat.

  • needurhelp1010needurhelp1010 Niagara FallsPosts: 5
    Thanks everyone, I'm going to replace the thermostat and give it a good burping on an incline. The rad cap is away from the actual rad. Let u know what happens. Cheers!
    The one question that's been bothering me is "Can I have a too concentrated mixture in the system?"
    The hydrometer reading is pretty high when Chevy says use a 50/50 mix.
    Can it harm things?
  • needurhelp1010needurhelp1010 Niagara FallsPosts: 5
    You guys are a wealth of information. I appreciate it. I didn't realize that there was a special color antifreeze for that car....I think mine is all green now. A flush?
  • needurhelp1010needurhelp1010 Niagara FallsPosts: 5
    I'm thinking a new thermostat and a coolant system flush might be a good idea. It would get rid of any residual stop-leak and put the heating/cooling system back to normal. Thanks! I'll let u know what happens.
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