Thermostat replacement?

Tiny
SHAWNDHICKMAN
  • MEMBER
  • 1999 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 12,000 MILES
How located and replace thermostat on my 1999 Chevy blazer?
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Tuesday, December 29th, 2009 AT 2:53 PM

23 Replies

Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
The thermostat is located between the water outlet and a housing built into the intake manifold.

Disconnect the negative battery cable.
Remove the air inlet duct.
Drain the cooling system to a level below the thermostat.
Remove the thermostat outlet-to-engine retainers (usually either 2 bolts or 1 bolt and 1 stud), then remove outlet from the intake manifold.
Remove the thermostat from the housing, noting the orientation for installation purposes.

To install:

Carefully clean the all traces of the old gasket or sealer from the housing and outlet.
Install the thermostat to the housing, oriented as noted during removal, then position a new gasket (if used).
Place a 1 / 8 in. bead of RTV sealant in the groove on the water outlet sealing surface, then install the outlet while the sealer is still wet.
Install the outlet retainers and tighten to 21 ft. lbs. (28 Nm) for the 4.3L 19-96 models or to 14 ft. lbs. (19 Nm) for the 1997-99 models.
Properly fill the engine cooling system and check for leaks.
Install the air inlet duct.

this guide will help walk you through the steps of changing the thermostat with diagrams below to show you how on your car.

https://www.2carpros.com/articles/replace-thermostat

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.
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Friday, August 16th, 2019 AT 11:50 AM
Tiny
GHAWTHORNE
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
How do I get to it and change the thermostat?
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Follow the upper radiator hose to the engine / thermostat housing. Under the housing is where the t-stat is located. Drain the coolant below the thermostat level, remove the upper hose, remove the retaining bolts on housing, and remove the housing. Pay close attention to the positioning of the old t stat. Make sure to install the new one facing the same direction. Also, make sure gasketed surfaces are clean and dry and reverse the process.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
KENT ONEIL
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 13,000 MILES
Temp gage in car reads 180 degrees but no heat is it the thermostat, or is there a sensor or valve that I dont know about in the heating system. Do not think it would be the thermostat.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Those Blazers used Dexcool from the factory and it had a tendency to plug up the heater core. Try having it backflushed (just the heater core) to see if it will work. I have seen them so plugged up they had to be changed
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
DOM.R.MATRA
  • MEMBER
  • 12 POSTS
  • 1997 CHEVROLET BLAZER
  • 14,000 MILES
I have a P0128, for coolant thermostat. Do I need to change the thermostat?
Also, I have a P0446. For Evap Emissions. What doe this fully mean?
Thanks.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
DOM.R.MATRA
  • MEMBER
  • 12 POSTS
I meant 140M miles.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
HOMER1967
  • MECHANIC
  • 875 POSTS
Yes you need to change the thermostat, that is a very very common issue on those vehicles, I do atleast one a month. The p0446 signifies that you have a leak in you evaporative system and could be anything from a bad or loose fuel cap, to a broken hose to a faulty valve. You need to take it to a shop that has the specialed equipment and knowledge to diagnose that code.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
FRIARBARB
  • MEMBER
  • 3 POSTS
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 119,000 MILES
I replaced the thermostat housing (it had developed a pin hole leak) and thermostat on my 96 Blazer, had the cooling system flushed.

After I did this, the engine temp gauge would steadily rise to around 240-250 for a few minutes then fall back to around 190 degrees. I checked the coolant resevoir and it is full, but there was not alot of coolant in the radiator itself.

I replaced the thermostat again and refilled the radiator. Same thing will happen. Tempature will rise to around 240 degrees, then fall back to 190 degrees in a few minutes.

Could I have another defective thermostat?
Could the radiator pressure cap be defective, not allowing coolant from the resevoir to flow back to the engine?

Robert
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
Your air bound. Run vehicle with the cap off until it warms up and all of the coolant will get sucked low in the radiator then fill the radiator itself and you will bea all set. There are no other problems just air bound. With the cap off and it running it might bubble out of radiator until the thermostat opens and then go empty real quick. This is normal, wait until you see it go empty then fill it. If your uneasy about this method then fill the radiator and let it get hot like it is now then let it cool and then refill radiator and repeat process until all the air is out. You cant fill a empty radiator from the overflow, it just wont work. Let me know how you make out
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
FRIARBARB
  • MEMBER
  • 3 POSTS
Tim,

Did as you advised and it worked fine for a bit. Then went for a short drive and the tempature climbed back to around 240 degrees. After a few minutes, temp dropped back to around 190 degrees.

When it cools off a bit I will check the radiator again and repeat the process you described previously.

Could this be an on going problem?

Thanks again.

Robert
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
Hello,

Not to step on any toes here, but to ad to mastertechtim. May I suggest jacking up the front of the vehicle as high as you can Safely Do. As everyone knows Air will Rise to the Highest Point. So if there is air in the engine and you jack it up it will work it's way toward the front of the engine were it will be easier to expel.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
VALBABE19
  • MEMBER
  • 1 POST
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
I have a 96' chevy blazer that has a coolant system issue. I have changed the thermostat and raidator cap recently. I even took my raidator out of my car to give it a good thorough cleaning.

My raidator holds fluid well. The problem I am having is the access tank runs dry. I have to put fluid in it almost everyday. I have checked the tank and hoses leading to it to make sure there was no leakage. Any ideas on what can make it run so dry?
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
These engines bleed out pretty quickly. This wont be a on going problem, just one more time adding coolant should do it. This system has a heater core bypass that goes to the top of the radiator and pushes the air through the system pretty fast. Keep us posted.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
First off, you can't flush a radiator once it gets crusted up inside so if the radiator is the problem, a new one is the only thing that will resolve that.
Since I'm sure you have already overheated it pretty good recently, there is a real good chance of a blown head gasket at this point. Your first step is to pressure test the cooling system and resolve any pressure loss issues or leaks found.
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
FRIARBARB
  • MEMBER
  • 3 POSTS
Tim,

Problem solved. Opened the radiator this morning, after cooling off all night, and it was full. Ran around abit and tempature settled in at around 190 degrees.

One question if you have the time.

Why, when the radiator was low on coolant, didn't any from the reservoir get siphoned back to the radiator?

Thanks again for taking the time to help me out.

Take the rest of the day off.

Robert
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
With so much air in system it does not build up enough vacuum when its low to pull the coolant in. When its full it only takes a little vacuum pressure to pull it in. For example when pressurizing a coolant system thats half empty it takes alot of air volume to fill in the void but when its full, only a little pressure is needed. Anyways happy motoring
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
MALINDA.C
  • MEMBER
  • 1 POST
  • 1995 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 240,000 MILES
I have a 1995 chev blazer. I recently got a new thermostat put in because I thought that was the problem. When I drive the heater gadge goes right up into the red. I was told to pull over & let it go back down past 100. The gadges all move when I come to a stop. But also the lights inside & out all flicker. Wondering what is wrong? Is it ok to drive? Or will I do more damage driving it?
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
You need to check to see if the temp is actually getting that hot. Rent a thermometer for testing radiator temp. With the engine cold, open the radiator and insert the thermometer. Allow the engine to warm up. The coolant should range between 195 and 205 degrees. If it goes above that, chances are the radiaror is plugged or there is other engine trouble.
Let me know what you find.
Joe
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Friday, September 11th, 2020 AT 3:35 PM (Merged)
Tiny
MEATY
  • MEMBER
  • 6 POSTS
  • 1994 CHEVROLET BLAZER
Heater problem
1994 Chevy Blazer 6 cyl Four Wheel Drive Automatic 50 000 miles

I have a 1994 s10 blazer and recently after the car is well warmed up, I am getting no heat reading from the temp gage in the digital dash cluster. I am assuming that it is a problem with the coolant temp sensor or the thermostat. The coolant levels seem to be fine. If the thermostat is bad, will not fixing it immediately cause any other problems since it is below freezing every night?
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Friday, September 11th, 2020 AT 3:35 PM (Merged)

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