thermostat replacement?

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.

How do I get to it and change the thermostat?

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.

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.

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

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.

I meant 140M miles.

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.

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

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

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

[quote:716f5647e1="mastertechtim"]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[/quote:716f5647e1]

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.

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?

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.

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.

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

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

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 ??

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

Heater problem
1994 Chevy Blazer 6 cyl Four Wheel Drive Automatic 50 000 miles
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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?

[quote:f4cac36b3c="meaty"]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?[/quote:f4cac36b3c]



No heat temp gauge reading cold
antifreeze full
1st step is to replace the thermostat

I have an 88 K5 Blazer with a 5.7 liter. I replaced all hoses, radiater, water pump, thermostat and housing. Also replaced the heater core. The truck never overheated before but was leaking every where. After I replaced all this it began overheating. When the thermostat is in it only gets hot on the P/S of the radiator. The lower hose, heater core supply and return line, and the thermostat housing all get hot along with the P/S tank on radiator. The upper hose and D/S of tank stay cool. Some one give me some thing before set the dang truck on fire.

Almost sounds like the wrong water pump. Which belt drive system do you have? If it's a serpentine with the pump driving off the back side the pump is reverse rotation. If it has V belt drive to the pump it is standard rotation. That can be a PIA from 87-89 because they used both drives depending on the options.

The other thing could be the thermostat is in upside down. OR it is a bad one OOB. Seen that happen more than once.