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CHECK COOLANT TEMP

C

Caslotillo

Full Member
Joined
Jul 26, 2021
Messages
9
Hello,
I have a 2002 Avalanche, and I keep getting the message, “Check Coolant Temp”. I replaced the water pump 2 years ago, and have replaced the thermostat last week. I replaced the coolant temp sensor today, and I am still getting this same error message. I was advised that there may be air in the cooling system, and to bleed the air out. I bought a coolant refill kit, with the funnel, and all the little attachments to bleed the air. I’m still getting the same error message. The heater blows cold air still, although while i was bleeding the air out of the system, the heater blew hot air just for a fed minutes, then started to blow cold air again. The temp gage still shows hot ant the message appear. I have sought help elsewhere, but some people think that I’m talking about the ”Low Coolant” message. This is not it. Can someone please help me? Thanks in advance.
 
It may be the radiator is blocked which is nothing you can do anything about except to replace it. But first get a flashlight and look at the radiator though the grille.
 
Thank you for your reply. So, when I look at the radiator, what part do I look at, and what am I looking for?
 
Bugs, leaks, and dirt. I'm in the habit of spraying a mild engine cleaning foam thru the grille on the radiator then let it set for 15 minutes then take a garden hose from the inside of the engine compartment thru the fan to spray it off.

A way to check is get a infrared thermometer and measure the temperature of the radiator from top to bottom the temp should be the same with no hot or cool spots. Then measure from side to side it should gradually cool off. PS the truck should be at normal operating temperature 160-180f

I'm going to assume you got all the air out of it.

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RYOBI introduces the Infrared Thermometer. To start saving on energy costs, use this RYOBI Non-Contact Infrared Thermometer to detect hot and cold spots near doors and windows and check air vents for efficiency. The thermometer's laser guide makes it easy to take temperature readings by clearly...
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I lived in a rural part of my state many years ago.

The mosquitoes around there were horrible due to the fact that most of the surrounding farmland was used to grow rice.

Besides the obvious problem of the mosquitoes biting people and animals, they also clogged vehicle radiators.

It was a common practice to pull out clogged radiators and take a pressure washer to both sides to clear the massive clogs of the dead critters.

No one I knew of gave that practice a second thought and this was a service offered at local mechanic shops.

My first experience with this was when I burned up the transmission in my 1990 Chevrolet Silverado.

During the repair, I found out the radiator was close to 80 percent clogged with mosquito debris.

Once everything was power washed, my truck ran much cooler and the a/c, for the first time since I owned the truck, was cold.

From then on, I always kept a close eye on the radiators of any vehicles we had that were driven from dusk to dawn on a regular basis.

Most did not have problems if they only drove during the day.

Just an example of some of the problems you can have depending upon where you live.
 
It's common sense although people do not realize if the bugs and road oils are hitting the windshield it's also going through the radiator and ac condenser
 
MS03 2500 said:
It's common sense although people do not realize if the bugs and road oils are hitting the windshield it's also going through the radiator and ac condenser
Click to expand...

And if I had to drive anywhere during mosquito season after dusk, which I tried to not do unless absolutely necessary, I would have to wash off my vehicle the next day.

There are a lot of vehicles there with bad paint jobs on the front ends because the bug guts would eat up the paint in short order.

Whenever you were outside doing outside things, everyone went indoors before the "Skeeter Truck" began making it's nightly rounds.

That "Skeeter Dope Spray" really made the mosquitoes mad.

A lot of the farm trucks had mosquito netting across the grills to help keep the radiators clean.

Those guys didn't have time to be messing around with pressure washers all the time and they were always out on the front lines.

It was an OK place to live, but I do not miss that aspect of it.
 
MS03 2500 said:
Bugs, leaks, and dirt. I'm in the habit of spraying a mild engine cleaning foam thru the grille on the radiator then let it set for 15 minutes then take a garden hose from the inside of the engine compartment thru the fan to spray it off.

A way to check is get a infrared thermometer and measure the temperature of the radiator from top to bottom the temp should be the same with no hot or cool spots. Then measure from side to side it should gradually cool off. PS the truck should be at normal operating temperature 160-180f

I'm going to assume you got all the air out of it.

www.homedepot.com

RYOBI 8 in. Infrared Thermometer IR002 - The Home Depot

RYOBI introduces the Infrared Thermometer. To start saving on energy costs, use this RYOBI Non-Contact Infrared Thermometer to detect hot and cold spots near doors and windows and check air vents for efficiency. The thermometer's laser guide makes it easy to take temperature readings by clearly...
www.homedepot.com
Click to expand...
This is interesting, thanks! If the radiator has cool spots, then it is a radiator problem, correct? And am I to assume that it just needs to be replaced?
 
Double check with your local mechanic, but it does not sound like the coolant is flowing thru it correctly. Is it the original one

I guess you could take the top hose off and see what it looks like inside. When it's cool of course.
 
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You state you do not have HEAT inside truck?

run engine for a few mins
Feel the top rad hose. does it get hot?
feel heater hoses that go to firewall do they get hot?

If no heat inside is different issue than CHECK COOLANT TEMP
What is temp on gage read inside?

Please describe everything happening.

What does the little MESSAGE CENTER window in cluster say?
CHECK COOLANT TEMP per manual means coolant is getting too hot. Page 2-119.
SO is this on when you first start i AM or after a while idling, short drive? ?

What does temp gage read?
Is top rad hose hot?
Are heater hoses hot?
Any coolant leak?
HOw is fan clutch? is fan loud when first start truck?
What level is overflow tank?
Did you flush system or just drain and replace?
 
The temp gauge Will climb gradually all the way to 260. The top hose is hot there is no coolant leaking, I actually just drained and replaced the fluid, and the overflow tank is fall to the fill line. I will check the heater hoses, and I’ll be back on here tomorrow. When the temp gauge climbs to 260, actually around 240 is when the check coolant temp light turns on. And there is no heat inside the truck. I will check the heater hoses tomorrow and update you. Thanks again for you guidance!
 
Are you driving? or what?
Engine FAN?

Have you driven since changing fluid?

IF engine hot and no heat inside? could be clogged internals.
 
Sounds like the T-Stat is stuck closed., little or no circulation. Replace the T-Stat or take it out and put in a pan of water and bring it to a boil and see if it opens at the stamped temp on it probably 195 or 210 deg.. Since water boils at 212 deg the 210 deg it may not open then I would just replace it since it not an expensive part usually under $25.00..

Good luck
 
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Caslotillo said:
The temp gauge Will climb gradually all the way to 260. The top hose is hot there is no coolant leaking, I actually just drained and replaced the fluid, and the overflow tank is fall to the fill line. I will check the heater hoses, and I’ll be back on here tomorrow. When the temp gauge climbs to 260, actually around 240 is when the check coolant temp light turns on. And there is no heat inside the truck. I will check the heater hoses tomorrow and update you. Thanks again for you guidance!
Click to expand...
Hi, I replaced my hoses and connections to the heater core. Have some pics in a previous message. Keep in mind its an '04 if its any different.
I'm replacing the reservoir cap today. Just in case its old.
Thats a great idea to wash the bugs off the radiator. Inspecting that today.
If I take my grill off, I will install a bug screen behind.
I remember travelling the Alaska Hwy in northern BC years ago and many vehicles had a big bug screen mounted on the front ends.
 
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How did you come out.

Caslotillo said:
The temp gauge Will climb gradually all the way to 260. The top hose is hot there is no coolant leaking, I actually just drained and replaced the fluid, and the overflow tank is fall to the fill line. I will check the heater hoses, and I’ll be back on here tomorrow. When the temp gauge climbs to 260, actually around 240 is when the check coolant temp light turns on. And there is no heat inside the truck. I will check the heater hoses tomorrow and update you. Thanks again for you guidance!
Click to expand...
 
Depending on where you live, you do want to be careful when washing out the radiator. If they get corroded enough you can straight up wipe out sections of the fin stack with a pressure washer.
 
Some things came up, but will be back at it this afternoon after work. I’ll be back with an update. I think I forgot to add that the thermostat was changed a couple of weeks ago. Alright, wish me luck for this afternoon, I’ll be checking all hoses.
 
Sometimes new parts are junk too..
 
ygmn said:
Sometimes new parts are junk too..
Click to expand...
Hello. I’m glad that you mentioned this. I was telling a friend of mine that I replaced my thermostat, and he asked me if the old one was stuck closed or open when I removed it. I told him it was in the open position, but I was able to squeeze it down. I asked how I can be sure the old was was even bad to begin with. I asked this because when I opened the box with the new thermostat, I noticed that the new thermostat was in the open position out of the box. I was able to squeeze it closed, just as i was able to do with the old one that I removed from the truck. The spring sprung back open. I don’t know anything about vehicles, and I have been going by what I‘be read online and watching YouTube. So, is the new thermostat supposed to be in the open or closed position? Do I need to remove it from the truck and exchange it? I called Autozone, and I asked if the thermostat should have been open out of the box, and they told me yes, that it’s good. My friend insists that it’s not, and in order to test a thermostat, I should be able to pour boiling water on it, and it should open, but if it’s already open, something’s not right. What say you?
 
Well now. I feel like an idiot LOL. This is not what I understood to be considered open. Yeah, I have no idea if it was open in that sense. No one has explained it like that. I said the big spring was sprung, but no one say, “That doesn’t mean OPEN, you dummy!” LOL. So, Do you think there is a need for me to pull the brand new thermostat off to make sure?
 
Can't hurt to be sure.
 
I have performed a down and dirty test of a thermostat by simply placing the thermostat in a pan of water on the stove and while using my digital thermometer, watch at or around what temp the thermostat opens up.

Probably not a precise test, but it will show you if the thermostat even opens and closes as it should and its not stuck in either position.
 
EXT4ME said:
I have performed a down and dirty test of a thermostat by simply placing the thermostat in a pan of water on the stove and while using my digital thermometer, watch at or around what temp the thermostat opens up.

Probably not a precise test, but it will show you if the thermostat even opens and closes as it should and its not stuck in either position.
Click to expand...
realistically, i'm not sure why that would be any less precise. The only difference really is that the glycol would change the boiling point of the water. Technically water impurities could affect the metal, but i would find that unlikely for such a short test.

If you wanted to be anal about, distilled water by itself is purer and wont have the extra minerals in it. Which is why it's the basis of a coolant mixture and not tap water.
 
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