Overheating

Tiny
KAIDEN650
  • MEMBER
  • 2006 CHEVROLET COLORADO
I have a 3.5L 4x4 that keeps overheating. The temp gauge runs hot at 3/4 on the freeway and idling. Turning on the heater reduces the temp by almost a 1/4. I just replaced the fan, belt, water pump, and DAX coolant. The radiator does not leak, and is in like new condition, and I am still having an overheating issue! How can I diagnose and fix the problem? What could be causing the issue? Please help
Wednesday, August 7th, 2013 AT 6:30 PM

12 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It could be a thermostat or head gasket problem. with engine hot and fan either disconnected so it won't run, place hand on various areas of radiator if you feel cold spots then the rad needs replacing. should be about same temp all over. have coolant system pressure checked for internal leaks.

Read these guides, they will help

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

https://www.2carpros.com/articles/engine-overheating-or-running-hot

https://www.2carpros.com/articles/radiator-pressure-test
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Thursday, August 8th, 2013 AT 6:12 AM
Tiny
KAIDEN650
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  • 9 POSTS
How can I tell if it is the thermostat or head gasket?
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Thursday, August 8th, 2013 AT 11:18 AM
Tiny
HMAC300
  • MECHANIC
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If you get the coolant system pressure tested and the pressure goes down then it's an internal leak like a head gasket, etc. Thermostat just replace it is easiest way. Pic enclosed.
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Thursday, August 8th, 2013 AT 12:11 PM
Tiny
KAIDEN650
  • MEMBER
  • 9 POSTS
  • 2006 CHEVROLET COLORADO
So, I have replaced the water pump, thermostat, did a coolant system flush, added new coolant, replaced the fan, belt, radiator cap, had radiator preassure tested but temp gauge is still reading 3 ticks above half way! The temp gauge used to stay at half way to a tick below. I was reading a couple forums that talked about thermostats having different bore sizes. Could that be the problem? Or does my temp sensor need to be replaced? I also heard the dash temp gauge isnt accurate so Should I buy a scangauge? Like this one www. Ultra-gauge. Com? Can anyone help with this issue?
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Wednesday, August 21st, 2019 AT 6:42 PM (Merged)
Tiny
TY ANDERSON
  • MECHANIC
  • 719 POSTS
Yes, these instrument clusters are not very accurate. In these situations I'll use an infrared thermometer to get temperatures from the cooling system and compare to engine coolant temperature sensor data.
A scan tool is useful but only as accurate as the sensor relaying the data. In this case if the temperature sensor is faulty it's is going to give incorrect data to you scan tool.
Are there any fault codes stored in the vehicle's computer? Check engine light? Do have the 3.5L or 2.8 engine? Talk to you soon, TY
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Wednesday, August 21st, 2019 AT 6:42 PM (Merged)
Tiny
KAIDEN650
  • MEMBER
  • 9 POSTS
I dont have a code reader yet, it will be delivered tomorrow so im not sure. But the check engine light is not on. It is a 3.5L
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Wednesday, August 21st, 2019 AT 6:42 PM (Merged)
Tiny
TY ANDERSON
  • MECHANIC
  • 719 POSTS
Let me know if you have any more questions. If the check engine light is not on there may not be any problem.
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)
Tiny
KAIDEN650
  • MEMBER
  • 9 POSTS
  • 2006 CHEVROLET COLORADO
  • 156,000 MILES
Just got my code reader. No Dtc codes.

. So, I have replaced the water pump, thermostat, did a coolant system flush, added new coolant, replaced the fan, belt, radiator cap, had radiator preassure tested but temp gauge is still reading 3 ticks above half way! The temp gauge used to stay at half way to a tick below. I was reading a couple forums that talked about thermostats having different bore sizes. Could that be the problem? Or does my temp sensor need to be replaced? I also heard the dash temp gauge isnt accurate so Should I buy a scangauge? Like this one www. Ultra-gauge. Com? Can anyone help with this issue?
.
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
I would get a infrared temp gun and see what the actual really is they have really cone down in price.
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)
Tiny
MADMIKE1735
  • MECHANIC
  • 951 POSTS
Let the truck get up to temp. Once the temp gauge climbs to 3/4, touch the upper, and lower radiator hoses. They should both be hot. If not, there is air, or a block somewhere.
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)
Tiny
JOHN ANSEL
  • MEMBER
  • 1 POST
  • 2006 CHEVROLET COLORADO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
My radiator temperature gauge rises in temperature after I shut off engine. When I restart engine temperature goes back down to near normal. Also when idleing temperature starts to go up
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
What you describe isn't really out of normal. It really depends on the temperature outside. When you shut it off that's called a hot soak, water isn't moving so thetemp goes up. As long as it goes down it's ok. During idle if it goes up a little I wouldn't worry about it. If it goes up substansially like it pegs the gauge then get it looked at. Make sure your fluids are full though.
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Wednesday, August 21st, 2019 AT 6:43 PM (Merged)

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