Overheating

Tiny
HOPMAN64
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 131,456 MILES
When I started to drive the truck I noticed after a while it started smoking and quickly turned off the engine and I parked it and let it cool off. Next I noticed a leakage in the water pump got that fixed, but still overheats with brand new antifreeze and recently changed the thermostat as well. Please help me I am currently in Iowa I am going to need the truck soon to go back to Texas in a few days! I have not driven it since then. I barely tried it out today 12/18/17 after changing the thermostat on the 12/16/17 of this year. I need some answers please. I need this truck to move around especially in Texas.
Monday, December 18th, 2017 AT 7:46 PM

11 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
How high did the temperature get? Are you 100% sure that you got the thermostat in correctly? Also, it is not unheard of to get a dud of a thermostat from the parts shops. If it is installed backwards, that would definitely cause the truck to overheat, as it cannot open and allow coolant to flow and cool the engine.

Start the engine and let it warm for a few minutes, watching the temperature gauge. Once it is around operating temperature, shut it off. Carefully feel the upper and lower radiator hoses. If one is warm/hot and the other is not warm at all or is barely warm, then you have some sort of blockage in the cooling system. Most likely cause is a bad or improperly installed thermostat.
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Tuesday, December 19th, 2017 AT 5:39 AM
Tiny
HOPMAN64
  • MEMBER
  • 8 POSTS
I installed it as carefully and properly as I could, but I had a previous friend come by and scan it with a computer. I cannot remember the code but he did mention a low coolant but by that time I had already place antifreeze in it. I will try it out later on today after 5:00 pm 12/19/2017.
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Tuesday, December 19th, 2017 AT 6:22 AM
Tiny
HOPMAN64
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  • 8 POSTS
It overheated allot quicker this time! And the hose when I checked them weren't warm at all.
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Tuesday, December 19th, 2017 AT 6:02 PM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
If you checked both hoses, and they weren't warm at all but the engine was overheating, then you have to be low on coolant. Seriously low at that. There could be a giant air bubble in the system. When the engine is cold, raise the hood. Take off the radiator cap. Start the engine. Turn the heat on, all the way up, full blast. And keep adding coolant every time it drops below full. Do this for 10 minutes.

Also, be sure that your cooling fan is running. Your truck has [in my opinion] an unusually complex cooling fan, being basically a combination of an electric fan and an old school clutch driven mechanical fan. All I can say is be sure that (1) it's running when the engine is and (2) that it speeds up as the engine warms up (according to AllData, it should run faster as the engine warms up). If it's not working properly, it'll obviously cause the engine to overheat.

A scan tool isn't going to tell you anything about an overheating problem unfortunately. The only way it could help you is if a coolant temp sensor is giving information that's well out of it's acceptable range.
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Tuesday, December 19th, 2017 AT 7:12 PM
Tiny
HOPMAN64
  • MEMBER
  • 8 POSTS
Ok I was told that option on the ac and adding coolant but I will try that tomorro w after work since it is probably still too hot even after a long while
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Tuesday, December 19th, 2017 AT 7:28 PM
Tiny
HOPMAN64
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  • 8 POSTS
Was told that option from a coworker
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Tuesday, December 19th, 2017 AT 7:30 PM
Tiny
HOPMAN64
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  • 8 POSTS
And also I did add a full gallon of anitfreeze last I heard the trailblazers take 2
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Tuesday, December 19th, 2017 AT 8:46 PM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
Definitely use the heat not the AC. The heat uses coolant to warm up the air by using a blower to push air through a miniature radiator (aka the heater core) with warm coolant running through it. If the car got low on coolant, then air got into the system, even that part of it, and needs to be bled out.

If this doesn't solve the problem, we'll have to look at the possibility of a blown cylinder head gasket.

As a matter of fact, check your engine oil before doing much to it. If its milky/muddy, then go no further, you almost certainly have a blown head gasket and I'll detail more tests to confirm
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Tuesday, December 19th, 2017 AT 8:46 PM
Tiny
HOPMAN64
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  • 8 POSTS
I don't how to use the heat all I can think of is the ac
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Tuesday, December 19th, 2017 AT 8:51 PM
Tiny
HARRY P
  • MECHANIC
  • 2,295 POSTS
Turn the temperature all the way up. That's the heat.
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Wednesday, December 20th, 2017 AT 2:50 AM
Tiny
HOPMAN64
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Ok got it
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Wednesday, December 20th, 2017 AT 4:27 AM

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