T-Stat Change

The heat in my 98 Blazer is at best cold. I would like to change the t-stat and flush the cooling system. How difficult a task is it? Is there a site that I can get directions from?

The dealer wanted $500 to flush and change the t-stat.

The thermostat is extremely easy to change, it is located in the housing where the upper radiator hose enters the engine, just pull the two bolts, take out the old stat, put the new one in and then put the bolts back piece of cake.

forgot to mention... you need to drain out a gallon of antifreeze before you start or it will make a mess when you pull the bolts

If you want to flush it yourself, follow one of these methods;

For system with Sludge:

Buy the following:
2 gallons of distilled water $1
2 gallons of Dexcool $20
Prestone Flush 'N Fill kit $4
Prestone Radiator "Flush" $4

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Flush, fill with water, get engine up to operating temperature and run for 20 minutes, allow to cool then, drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.

Throw the stock AC Delco Radiator Cap away and buy a Stant from Advance Auto.




For clogged, neglicted, or extremely dirty systems:

Buy the following:

2 gallons of distilled water $1
2 gallons of Dexcool $20
Prestone Flush 'N Fill kit $4
Prestone Radiator "cleaner" not "flush" $6

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Cleaner, fill with water, run the engine 3-6 hours (you can leave it in for a few days if neccessary), drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.

Throw the stock AC Delco Radiator Cap away and buy a Stant from Advance Auto.

The heat in my 98 Blazer is at best cold. I would like to change the t-stat and flush the cooling system. How difficult a task is it? Is there a site that I can get directions from?

The dealer wanted $500 to flush and change the t-stat.

Walk away from that dealer and NEVER go back there again.

$500 for a stat and flush and fill?

try $150 MAX

In fact, go in there and rip them a new asshole for trying to rip you off.

Walk away from that dealer and NEVER go back there again.

$500 for a stat and flush and fill?

try $150 MAX

In fact, go in there and rip them a new asshole for trying to rip you off.


I agree $500 is way too much, but that is probably what most dealers would charge. Their procedure is about the same as I recommend for neglicted systems. That $500 includes:
6 hours of labor for the flush
the cleaner
two radiator caps
a flush 'N Fill kit
two gallons of dexcool

and they are probably charging an hour for the ten minutes it takes to change the stat as well as the cost of the thermostat.

The heat in my 98 Blazer is at best cold. I would like to change the t-stat and flush the cooling system. How difficult a task is it? Is there a site that I can get directions from?

The dealer wanted $500 to flush and change the t-stat.

Stay away from the stealerships! It is a fairly simple job if you are mechanically inclined and have a few basic tools.

Are you saying that the heater for inside the truck is blowing cold air? Or the engine runs Cold? Does the engine seem to reach its normal operating temperature? Is the antifreeze muddy and nasty looking?

You can do a reasonably good flush job at home with a bottle of Radiator Cleaner and a garden hose. The T-stat shouldn't be more than a couple of bolts and a rubber gasket. I would suggest a Prestone Flush and Fill kit available at AutoZone or any Parts store. Make sure you get a new Radiator cap too.

If you think your system is in pretty bad shape, I recommend you find a local Garage that can do a Reverse Power flush. Get out your Yellow Pages and call local Radiator shops or reputable garages asking for quotes on a Reverse Power Radiator Flush. This will clean your system as good as can be done without a lot of trouble. I would think the entire job would run approx. $100 - $200 USD which would include the new thermostat and antifreeze.

-The engine is running about two ticks the left of 210.
-The system is blowing cold unless it about 30 degress outside, then it is warm, but not hot.
-The fluid is clean.

I appreciate the quick responses. Thank you.

You might just need the heater core flushed out. With the engine cool and not running, remove BOTH heater hoses from the connections at the Firewall (You will spill a little coolant) and flush the connectors with a garden hose. I would alternate back and forth flushing the core in both directions. This should blow out any sediment. Re-attach the heater hoses and top off your Antifreeze.

Do you think my engine is running a little cold?

You might just need the heater core flushed out. With the engine cool and not running, remove BOTH heater hoses from the connections at the Firewall (You will spill a little coolant) and flush the connectors with a garden hose. I would alternate back and forth flushing the core in both directions. This should blow out any sediment. Re-attach the heater hoses and top off your Antifreeze.


It does seem a little on the cold side, you may need to go ahead and change the T-Stat too.

I agree $500 is way too much, but that is probably what most dealers would charge. Their procedure is about the same as I recommend for neglicted systems. That $500 includes:
6 hours of labor for the flush
the cleaner
two radiator caps
a flush 'N Fill kit
two gallons of dexcool

and they are probably charging an hour for the ten minutes it takes to change the stat as well as the cost of the thermostat.

Nope, that is a RIPOFF period.

I had my stat stick open two years ago and they flushed my system, triple reverse flushed my heater core, installed new coolant and a new stat for $143 canadian.

That is US$120 bucks which included taxes.

Saying that 500 for this job is warranted is pure nonsense.

Here's a quick question.

Which way does the coolant flow through the heater core, In through the large hose and out through the small hose or vice-versa?

Knowing this would help when performing a reverse flush on the Heater Core.

Doesn't really matter seeing you should be flushing both ways for a proper flush.

Nope, that is a RIPOFF period.

I had my stat stick open two years ago and they flushed my system, triple reverse flushed my heater core, installed new coolant and a new stat for $143 canadian.

That is US$120 bucks which included taxes.

Saying that 500 for this job is warranted is pure nonsense.

Was that at the chevy dealer? It is was they didn't follow their own guide lines?

I never said that it was warranted, merely explain how they reached that price.

Yip, at the local Chevy Dealer here.

Yip, at the local Chevy Dealer here.

Either they were really nice to you or they didn't follow procedure. Did it take all day?

Let me clarify, I'm not saying that $500 is worth it, I don't believe they should charge you for time that your car is outside running and they're not working on it.

This is what they were suppose to do:

1996-2000 Chevrolet and GMC S/T Models (Blazer, Jimmy, Sonoma, S10 Pickup)

1998-2000 GMC Envoy

1996-2000 Oldsmobile Bravada

with 4.3L V6 Engine (VINs W, X -- RPOs L35, LF6)

This bulletin is being revised to include additional model years. Please discard Corporate Bulletin Number 99-06-02-012C (Section 06 -- Engine).

Condition
Some customers may comment that the heater is inoperative, blows cold air, engine may exhibit an overheat condition or the coolant reservoir has rust in it.

Cause
Vehicles equipped with DEX-COOL® coolant, which may have been operated for extended periods of time with a low coolant level, usually in excess of 32,000 km (20,000 mi), may be susceptible to the formation of a rust-like material in the cooling system.

Correction
Flush the cooling system using the repair procedures that follow.

Parts and equipment required/suggested for this correction are listed below.

1 each *Prestone® Flush and Fill Kit #AF-KITP U.S. (#00050 in Canada). This kit can be obtained from your local parts supplier and can be used on all vehicles repaired under this procedure. Save it after performing the repair, as it is reusable.
1 each *Prestone® Heavy Duty Cooling System Cleaner, GM P/N 12346500 - 1 per vehicle. This cleaner is in powder form and contains a neutralizer. Do not substitute other cleaners. The diluted cleaners that are available in liquid form are not recommended for this repair.
5.7 L (6 qt) of 100% (non-diluted) DEX-COOL® coolant (GM Spec 6277M).
1 each new thermostat, GM P/N 12563335.
2 each new radiator cap, GM P/N 15075565.
1 each *Prestone® yellow funnel. This funnel can also be obtained from your local parts supplier. It fits snugly into the radiator opening for an easy fill and is reusable.
*We believe this source and their products to be reliable. There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any such items which may be available from other sources.


Important
Verify the fuel level in the fuel tank. The fuel level should be above ¼ tank before this procedure is started.

As a precaution, verify the oil level in the crankcase. Add the amount required to bring the oil level into the normal range.

It is recommended the vehicle be placed in a position so that the following are available:

A sanitary sewer -- not a storm drain, etc
A monoxivent system (if the outside temperature is less than 10°C (50°F)).
Hot running water


Notice
Due to the complexity of these procedures, the following repair steps must be strictly adhered to in order to achieve the intended results. Any deviation or substitution may result in sub-standard cleaning/flushing results or system damage.


Diagnostic Procedure
Install the Scan Tool. This will allow monitoring of the coolant temperature throughout the procedure.

Caution
As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the radiator cap while the engine is hot and pressure is high will cause the solution to boil instantaneously - possibly with explosive force - spewing the solution over the engine, fenders and the person removing the cap. Under some conditions, the engine coolant is combustible.



Important
The installation of a NEW radiator cap at the beginning of this procedure and the second new cap at the end of the repair procedure is necessary in order for the correct pressure to be achieved and for the repair to be completed successfully.
The radiator cap is NOT a good indicator of the general condition of the cooling system. Typically the underside of the radiator cap will exhibit a greater amount of contamination than the rest of the system. It is important to evaluate the condition of the cooling system by checking the following before beginning the repair procedure:

Remove the radiator cap. Install a new radiator cap, GM P/N 15075565. A properly operating radiator cap is essential for this procedure to work properly. Be sure to wipe off all radiator cap sealing surfaces prior to installation.
Start the engine.
Using a flashlight or lead light, look into the radiator. From the right side of the vehicle, peer into the radiator toward the left side of the vehicle. Observe the top three rows (or tubes) of the radiator. (It may be necessary to drain off some of the coolant to see the top three rows of the radiator). If it appears the coolant is able to flow through the third row down from the top, the vehicle should be repaired using Procedure A. If it appears the coolant is NOT able to flow through the third row down from the top, then the vehicle should be repaired using Procedure B.
Stop the engine.
Repair Procedure A & B

Important
If available, use coolant exchanger Pro-Fill 42-75100-KM, Power Flush 211-07601/DEX (available through the GM Dealer Equipment program), or equivalent to evacuate the system of coolant. Follow the manufacturer's instructions for exchanging used coolant with new coolant. However, for this procedure, use water in place of new coolant. Be sure to exchange 1½ times the cooling system capacity of the vehicle with water. This will ensure that only water remains within the cooling system. Once the coolant has been displaced with water, drain the water from the radiator.
If you are located within an area which regulates the disposal of used coolant (check with your local water treatment facility), all coolant and coolant/water mixture must be captured until the water runs clear of coolant. Use a clean 208 L (55 gal) drum or similar to contain the waste coolant. Refer to Corporate Bulletin Number 00-06-02-006 for information on coolant recycling and removal services.

Drain and properly dispose of the coolant.

Caution
Any obstructions in the hoses to or from the coolant recovery bottle may cause over-pressurization of the cooling system. This over-pressurization could result in serious personal injury.


Inspect the following hoses in order to assure there are no obstructions and the coolant is able to flow freely:
The hose to the coolant recovery bottle.
The relief hose from the coolant recovery bottle.
Disconnect both coolant hoses to the heater core from the engine.
Back flush the heater core for 5 minutes after clear water is present. Pressurized water not to exceed 345 Kpa (50 psi), may be used.
Reinstall the heater return hose to the engine.
Install the radiator cap and properly tighten.
Install the "T" from the flush and fill kit to a 25.4 cm (10 in) piece of 19 mm (¾ in) heater hose. Tighten the clamp.
Install the hose to the engine. Tighten the clamp.
Install the other end of the "T" in the heater core inlet hose. Tighten the clamp.
Disconnect the upper radiator hose from the radiator. Properly position the hose, so the accessory drive belt or any pulley/belt cannot touch the hose.
If you used coolant exchange equipment, disconnect it.
Attach a garden hose to the "T" of the flush and fill kit. Turn on the water and back flush the cooling system for at least two minutes after the water runs clear.
Start the engine and continue back flushing the cooling system for five additional minutes.
Turn the engine "OFF".
Turn the water "OFF".
Re-attach the upper radiator hose to the radiator.
Open the radiator drain and drain all water from the radiator.
Remove the lower left water pump crossover bolt. This allows lowering the water level in the left side of the engine.
After the water stops running from the water pump bolt hole, reinstall the bolt.
Close the radiator drain.
Mix the Prestone® Heavy Duty Cooling System Cleaner, GM P/N 12346500, in approximately 3 L (3 qt) of warm water. Pour the mixture into the radiator. Top off the system with plain water and reinstall the radiator cap.
Run the engine at 1600 to 1800 RPM with the air conditioning in the maximum cool position. To achieve the 1600 to 1800 RPM, place a dime between the closed throttle stop and the screw. This screw should never be adjusted, under any circumstance. Its only purpose is to keep the throttle plate from sticking in the bore when the throttle is slammed shut. It is not a minimum idle (RPM) control adjustment screw.

Important
It is imperative that all air pockets have been removed from the cooling system in order for the cleaning procedure to be effective.

Service Procedure A
For Service Procedure A, the cleaner should be left in the system for three hours (after normal operating temperature of the cooling system has been achieved). Normal operating temperature is when the coolant temperature stabilizes around 98°C (200°F). The best results are obtained when the coolant temperature is between 98°C (200°F) and 110°C (230°F). DO NOT EXCEED 113°C (235°F). Use the Scan Tool to determine when this point has been reached. When this temperature has been reached, start the clock. Periodically (every twenty minutes or so), monitor the coolant temperature and engine during the three hour run time. A half hour has been built into the actual labor time to cover for the time spent monitoring the engine, etc.

In order to achieve a constant temperature of 98°C (200°F) to 110°C (230°F) during this procedure, maintain the idle speed, turn on the A/C or partially close the hood.

Service Procedure B
For Service Procedure B, the cleaner should be left in the system for two and a half hours (after normal operating temperature of the cooling system has been achieved). Normal operating temperature is when the coolant temperature stabilizes around 98°C (200°F). The best results are obtained when the coolant temperature is between 98°C (200°F) and 110°C (230°F). DO NOT EXCEED 113°C (235°F). Use the Scan Tool to determine when this point has been reached. When this temperature has been reached, start the clock. Periodically (every twenty minutes or so), monitor the coolant temperature and engine during the two and a half hour run time. A half hour has been built into the actual labor time to cover for the time spent monitoring the engine, etc.

In order to achieve a constant temperature of 98°C (200°F) to 110°C (230°F) during this procedure, maintain the idle speed, turn on the A/C or partially close the hood.



Important
The vehicle should not be left idling outdoors when the ambient temperature is below 10°C (50°F). The flushing procedure relies on heat as a catalyst in order to be effective. Ambient temperatures below 10°C (50°F) do not allow sufficient cycling of the thermostat to effectively clean the cooling system.


Turn off the engine.
Remove the dime from the closed throttle stop screw. Do NOT remove the radiator cap. Following the procedure listed below will assist you in draining the cooling system thoroughly.
Place a drain pan under the radiator drain hose.

Caution
The cooling system and coolant are hot and under pressure. Loosen only the radiator drain until the pressure has been released from the cooling system and follow the procedures exactly in this bulletin, using normal safety precautions to avoid being injured by the hot coolant mixture.


Loosen the radiator drain. Drain approximately 1 L (1 qt) of liquid from the system.
After the pressure has been released from the cooling system, slowly loosen the radiator cap to the safety stop. Do not remove the cap (This releases the spring pressure on the secondary seal while retaining the primary seal to the top of the filler neck and will allow the coolant reservoir to be evacuated).
When the coolant reservoir is empty, re-tighten the radiator cap fully.
Remove the cap from the flush and fill "T". This will allow the coolant to be siphoned from the heater core and the engine block.
When the water has stopped coming out of the radiator drain hose, close the radiator drain. Do not place the cap on the "T".
Using Prestone® Heavy Duty Cooling System Cleaner, GM P/N 12346500, mix the neutralizer (from the bottom of the can) with approximately 3 L (3 qt) of warm (shower temperature) water.

Notice
Do not put cold water into a hot engine as engine damage may occur.

Under no circumstances should the neutralizer be left in the cooling system for any longer than ten minutes once the vehicle has reached operating temperature (thermostat open). The neutralizer is corrosive to aluminum and will damage system components if it is left in the cooling system for longer than ten minutes.


Pour the mixture from the step above into the radiator.
Completely refill the cooling system with warm to hot water through the "T". When the radiator is full, install the radiator cap to the safety catch. Continue to fill until the overflow reservoir is filled to the hot line on the reservoir.
Remove the fill hose and install the cap on the "T" and the radiator fully.

Important
It is imperative that all air pockets have been removed in order for the procedure to be effective.


Start the engine. After engine speed stabilizes, reinstall the dime between the closed throttle stop and the screw. With the A/C on, bring the cooling system back to normal operating temperature and follow the directions on the can.
Turn off the engine.
Remove the dime from the closed throttle stop and the screw.

Caution
As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the radiator cap while the engine is hot and pressure is high will cause the solution to boil instantaneously - possibly with explosive force - spewing the solution over the engine, fenders and the person removing the cap.


Drain the cooling system, following the procedure listed in Step 24 above.
Do not close the radiator drain. Leave it open.
Disconnect the upper radiator hose from the radiator. Properly position the hose, so the accessory drive belt or any pulley/belt cannot touch the hose.
Attach a garden hose to the "T" of the flush and fill kit. Turn on the water and back flush the cooling system for at least two minutes after the water runs clear.
Start the engine and continue back flushing the cooling system for five additional minutes.
Turn the engine "OFF".
Turn the water "OFF".
Close the radiator drain.

Important
If the repair is a Procedure A, go to Step 40.

If the repair is a Procedure B, remove the radiator and have it recorded and steam clean the end tanks. After reinstalling the radiator, continue to Step 40.


Remove the air cleaner housing and tube assembly from the throttle body.
Remove the two nuts holding the throttle cable bracket to the throttle body and position the bracket and the cables out of the way.
Remove the thermostat.
Remove the previously installed flush kit "T" and hose. Save for future use on other vehicles.
Install the heater inlet hose to the intake manifold and secure with the original spring clamp.
Inspect the thermostat opening and cover for foreign material. Clean if necessary.
Remove the left lower water pump crossover bolt to drain the left side of the block and the left cylinder head.
Install sealant to the bolt threads, using GM P/N 12346004 (Canada GM P/N 10953480), or equivalent and reinstall the water pump crossover bolt. Tighten
Tighten the bolt to 41 N·m (30 lb ft).

If available, use coolant exchanger Pro-Fill, Power Flush, or equivalent to fill the system with 50/50 DEX-COOL® coolant. If a coolant exchanger is not available, proceed to the next step now. Follow the manufacturer's instructions for system fill/coolant exchange. If you are using coolant exchange equipment, you will need to install a new thermostat, GM P/N 12563335 and top off the system with clean drinkable water prior to exchanging. After exchanging, install the upper radiator hose and clean out the coolant recovery bottle. Proceed to Step 56.
Pour 5.6784 L (6 qts) of 100% (not pre-mixed) DEX-COOL® coolant into a clean container.
Using a clean funnel, pour as much of the 100% DEX-COOL® coolant that you can into the engine through the thermostat opening.
Install a new thermostat, GM P/N 12563335. Tighten
Tighten the bolt to the specified torque of 19 N·m (14 lb ft).

Hold the upper radiator hose in the straight up position and pour 0.473 L (1 pint) of the 100% DEX-COOL® coolant into the hose.
Install the upper radiator hose to the radiator and properly position the clamp.
Flush the coolant recovery bottle thoroughly.
Complete the fill of the cooling system with the balance of the 5.7 L (6 qt) of 100% DEX-COOL® coolant and top off with plain water. If the water is not drinkable, do not use. Water must be clean and fresh.

Important
The second new radiator cap must be installed at this point of the procedure. It is possible that small contaminants may have become lodged in portions of the first cap during the cleaning procedure.


Clean the radiator cap sealing surfaces on the radiator. Install the radiator cap, GM P/N 15075565.

Important
It is imperative that all air pockets have been removed in order for the cooling system to function properly.


Run the engine to operating temperature with the air conditioning in the maximum cool position for ten minutes.

Caution
As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the radiator cap while the engine is hot and pressure is high will cause the solution to boil instantaneously - possibly with explosive force - spewing the solution over the engine, fenders and the person removing the cap. Under some conditions, the engine coolant is combustible.


Turn the engine "OFF" and let it cool.
Check the coolant concentration for a 50/50 mix, using refractometer J 26568 (Centigrade scale) or J 23688 (Fahrenheit scale). Follow the manufacturer's directions for using the coolant tester. Unless your coolant tester has a provision for temperature correction, it is imperative that the correct coolant temperature is achieved when testing the coolant. If the coolant is warmer or cooler, the reading may be incorrect.
Top off the radiator and fill the coolant recovery bottle to 2.54 cm (1 in) above the full hot mark on the coolant reservoir. Add the appropriate coolant mixture to come to a 50/50 mix of the DEX-COOL® coolant.

Important
To assure intended system performance, inform the customer that the cooling system MUST be maintained in a completely full condition.


Parts Information
Part Number
Description

12346500
Prestone® Heavy Duty Cooling System Cleaner

12563335
Thermostat

15075565
Radiator Cap

I agree $500 is way too much, but that is probably what most dealers would charge. Their procedure is about the same as I recommend for neglicted systems. That $500 includes:
6 hours of labor for the flush
the cleaner
two radiator caps
a flush 'N Fill kit
two gallons of dexcool

and they are probably charging an hour for the ten minutes it takes to change the stat as well as the cost of the thermostat.

I was wrong about the extra hour for the t-stat chage, it is included in the standard procedure.

It does not take 5 hours to flush a cooling system.

They followed procedure and did the job right.