I have a 2001 C5 Coupe that I run low and high speed autocross. During the process on the 2nd and 3rd run of an event coolant temps are getting to 239 after the run and at best cooling to 229. I have turned on the air to bring it down, but in staging I am sitting at 228. Normal running temp is around 199. I need to stay stock for my class. Any thoughts? I have seen the same thing on my wife's 2001 coupe during runs. Track days are brutal on both cars.
C5 Cooling System
- Thread starter jrhott
- Start date
c4c5specialist
Technical Advisor
HI there,
I would be looking at the radiator assembly for debris.
There must be something there, as you should probably be cycling between 190-210 with extended idling and the AC on.
With AC the fans are on constantly, so that should bring your temps down, IF your cooling module is flowing air through it correctly.
Allthebest, c4c5
I would be looking at the radiator assembly for debris.
There must be something there, as you should probably be cycling between 190-210 with extended idling and the AC on.
With AC the fans are on constantly, so that should bring your temps down, IF your cooling module is flowing air through it correctly.
Allthebest, c4c5
napacruzerC5
Well-known member
I turn on the air between runs to get all the fans working with the engine running. Do you also open the hood? The term "heat soak" come to mind when you don't open the hood. If I have enough time between runs I will open the hood. Sometimes in smaller run groups there isn't enough time between runs to unbuckle the 6-pt harness, get out, open the hood, wait to be told to get back in line, close the hood, buckle up (then can't close the door all buckled up
) , unbuckle, close the door, buckle up and run. I sometimes forget and keep the air on; doesn't seem to hurt any.
) , unbuckle, close the door, buckle up and run. I sometimes forget and keep the air on; doesn't seem to hurt any.
bartfly
Member
I autocross regularly and have done a few track days. My 2004 is the same. Runs hot after the first run but never overheats ie boils over. I am in Las Vegas so our summer events are hot. C4C5 has good advise, make sure the radiator is clean. I clean mine each year and we don't have a lot of leaves in the desert but it does suck up things.
Gentlemen,
Kind of related to the issue of cooling. I changed the thermostat on my '03 Z06 yesterday. When I took the thermostat off, all the coolant came pouring out, kind of expected that. Now what I also expected was to see a fill cap on the radiator but I did not see one.
Do I just fill through the reservoir and it'll cycle through the radiator and into the block?
Also, how do you guys feel about the life expectancy of the Dex Cool? Do you trust that it'll last that long or do you change before?
Kind of related to the issue of cooling. I changed the thermostat on my '03 Z06 yesterday. When I took the thermostat off, all the coolant came pouring out, kind of expected that. Now what I also expected was to see a fill cap on the radiator but I did not see one.
Do I just fill through the reservoir and it'll cycle through the radiator and into the block?
Also, how do you guys feel about the life expectancy of the Dex Cool? Do you trust that it'll last that long or do you change before?
Junkman2008
Well-known member
I don't find that to be the case at all. If you cooling system is working as it should with no disruption (do to blockage or worn parts), it is more than adequate at keeping the engine cool. You have to take into consideration all the testing that was done with the LS engine series before the parts were chosen. If there was a overheating issue, it would have been noticed during engineering and addressed.
A lot of guys who experience overheating issues have flaws in their cooling system that they have not addressed or are not aware of. If they addressed their problems instead of trying to redesign the system, they would resolve their issues.
Yes, you fill the system through the reservoir tank. As for DEX-COOL. I think (I'm not 100% sure) that the service manual states to change the fluid every 60 months. I have had to drain my fluid for various repairs throughout my cooling system's life so I haven't quite made it that far. I will say that I have smelled some funky DEX-COOL before and if it smells super funky, I'd change it. It takes quite a bit of time for it to get as funky as I'm talking about. Probably close to that 60 months.
Vette_Dreaming
Well-known member
What do you suggest to clean the radiator? I have been experiencing my 2000 running very hot lately and I think I need to clean the radiator; but what is the best way?
Junkman2008
Well-known member
longspur
Well-known member
xplosive performance
Active member
If all the good suggestions don't solve the problem try adding DEI radiator relief it really does work. we have seen a drop of 15-20 degress
New Radiator Relief™
New Radiator Relief™
Junkman2008
Well-known member
Going into to detail, can you explain exactly how this product works? I am of the mindset that you must address the problem in order to solve it instead of redesigning the system (i.e., installing a bigger radiator). The way I feel is that if the original design worked when the car was new and you have not redesigned your engine, then the original design should still work 100,000 miles later. That is of course if no part of the original design has not worn out. If a part is worn out then no additive is going to help and again, you need to address the problem. I am also a little leery about pouring anything into the engine without knowing what it is doing. The service manual speaks about this also and that's pretty much the bible that I go by.
I look at engine repair like raising kids. If you have 3 kids and one is a problem, you don't extend what the kids can get away with by opening up the accepted behavioral parameters to the other two, you take care of the one that is bad. You address the problem, not redesign your parenting skills.
xplosive performance
Active member
Well without writing a book a couple things happen in a cooling system. Todays radiators are aluminium as we all know, aluminium in itsself is a very good heat sink drawing heat away from water (radiator) or air (intercoolers). Over a period of time the aluminium forms it natural oxide film to protect itself, that film also is a heat barrier dropping the efficiency of heat tranfer of the coolant. Now if you also have not routinely changed your coolant the coolant breaks down and also drops the heat transfer rate for cooling. Radiator Relief (and other similar products) combine several thermal additives designed to increase the cooling efficiency of any stock or aftermarket radiator. Reduce engine temperatures up to 30°F with new anti-foam formulas using corrosion inhibitors.
Now i agree with you to some extent but that's a long long conversation. Having spent many many years working with the automotive companies both domestic and foreign their designs are not always optimal, their driving force is not building a great trouble free auto or having the best part in place, getting by is just fine for them. And getting by is 12 months 12,000 miles. Yes they have come a long way.
Many many things can effect cooling how the car is driven where it is driven and how you take care of it. When you beat on it on the track the stock system as the way the car came off the line my not be up to the demands your now asking it to do. and a little help is needed.
Now i agree with you to some extent but that's a long long conversation. Having spent many many years working with the automotive companies both domestic and foreign their designs are not always optimal, their driving force is not building a great trouble free auto or having the best part in place, getting by is just fine for them. And getting by is 12 months 12,000 miles. Yes they have come a long way.
Many many things can effect cooling how the car is driven where it is driven and how you take care of it. When you beat on it on the track the stock system as the way the car came off the line my not be up to the demands your now asking it to do. and a little help is needed.
Junkman2008
Well-known member
Okay, although I wouldn't have minded the book! 
I think if you exclude extensive track time, the stock C5 cooling system on a stock C5 engine is more than capable of keeping the engine cool with everyday driving, even in high climate areas. I am located in the lovely Ohio Valley where humidity can be deadly to both humans and machinery so that is the experience I speak from. Anytime that I ever had temperatures that exceeded 235 degrees, it was due to something in my cooling system failing. Once I replaced the bad part, the cooling issue went away and the car ran a constant 220 degrees. Thus, I always instruct guys to address the problem and not redesign the system.
I hope that anyone reading this doesn't think that an additive is going to fix something that is broke (i.e. a leaking water pump or cracked radiator), which are just 2 common issues these cars can experience with high miles. Like I said, I addressed all my coolant issues and sitting in rush hour traffic doesn't affect my temperatures at all. The car stay at the correct temperature just as it did when new.
Thanks for the explanation.
I think if you exclude extensive track time, the stock C5 cooling system on a stock C5 engine is more than capable of keeping the engine cool with everyday driving, even in high climate areas. I am located in the lovely Ohio Valley where humidity can be deadly to both humans and machinery so that is the experience I speak from. Anytime that I ever had temperatures that exceeded 235 degrees, it was due to something in my cooling system failing. Once I replaced the bad part, the cooling issue went away and the car ran a constant 220 degrees. Thus, I always instruct guys to address the problem and not redesign the system.
I hope that anyone reading this doesn't think that an additive is going to fix something that is broke (i.e. a leaking water pump or cracked radiator), which are just 2 common issues these cars can experience with high miles. Like I said, I addressed all my coolant issues and sitting in rush hour traffic doesn't affect my temperatures at all. The car stay at the correct temperature just as it did when new.
Thanks for the explanation.
xplosive performance
Active member
I don't disagree with you at all. Fix the real problem first then make it better. Put in the additive and watch your temp drop to 192 while sitting in traffic thats all i'm saying.
Junkman2008
Well-known member
I would like to try it to see if it works but isn't that lower than the designed operating temperature?
longspur
Well-known member
What are the correct temperatures when new ?
On a hot day my car will stay at 190 all day long while driving with normal stop and go.
When sitting in stop and go traffiic is when I start to look at the guages
They have got as high as 225 - I assume this is normal or is it?
At what temp do you say I should shut this thing down.
On a hot day my car will stay at 190 all day long while driving with normal stop and go.
When sitting in stop and go traffiic is when I start to look at the guages
They have got as high as 225 - I assume this is normal or is it?
At what temp do you say I should shut this thing down.
xplosive performance
Active member
I am like you what is normal operating temp. we try to run our cars in the 185-210 range. We believe that cooler is better. Is 225 high when sitting in dead stop traffic probably not for short periods of time. This is also why we add such products as Radiator Relief to our cooling systems. When in traffic i would rather be at 199 dead stopped then 235. Again once you start to move and can get air across the radiator everything drops very quickly. Also remember depending on where you are located has a lot of effect on your cooling. Here in lovely FL for 9 of the 12 months we see daytime temps of 80 or better in the summer your trying to cool your radiator with air temps of 100 plus degrees. Conversely in the north your trying to get your engine temps up quickly in the winter.
The bottom line is this.
Maintain your cooling system with the proper ratio of water to coolant. Drain and flush the cooling system at least once a year if you drive hard or are in very hot or cold climates. The owners manual may not recommend this we do. A few dollars in coolant and labor is cheap in comparision to the alternative. Most people tend to ignore the cooling system until something goes wrong and then its to late.
Add or not add coolant additives like Radiator Relief by DEI or Water Wetter by Red Line is up to you we are firm believers in these products. We race cars and push them to the max and we don't have coolant related failures. We build a lot of street rods and cruisers where guys are driving slow and low for extended periods with radical motors and the systems never over heat. For $10.00 what do you have to lose.
The bottom line is this.
Maintain your cooling system with the proper ratio of water to coolant. Drain and flush the cooling system at least once a year if you drive hard or are in very hot or cold climates. The owners manual may not recommend this we do. A few dollars in coolant and labor is cheap in comparision to the alternative. Most people tend to ignore the cooling system until something goes wrong and then its to late.
Add or not add coolant additives like Radiator Relief by DEI or Water Wetter by Red Line is up to you we are firm believers in these products. We race cars and push them to the max and we don't have coolant related failures. We build a lot of street rods and cruisers where guys are driving slow and low for extended periods with radical motors and the systems never over heat. For $10.00 what do you have to lose.
Junkman2008
Well-known member
I dug into my service manual and located the following. It appears that there is no "set" value as to the operating temperature, but "range" in which the temperatures would be considered normal. This is how the car performed when new or when running optimal.
Cooling System Description and Operation
Cooling Fan Control
The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage and ignition 1 voltage from the underhood electrical center. The ground path is provided at G102.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan 3 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 3 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).
Engine Coolant Indicator(s)
COOLANT OVER TEMP The IPC illuminates the COOLANT OVER TEMP indicator in the message center when the following occurs:
The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the system cools slowly or not at all. This allows the engine to warm quickly.
Cooling Cycle Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Some coolant will then be pumped from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.
Coolant is also pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.
The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.
Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in keeping the throttle body cool.
From the cylinder heads, the coolant is then forced to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or it will flow through the thermostat and into the radiator where it is cooled and the coolant cycle is completed.
Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components:
Coolant The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and clean drinkable water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.
Radiator The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a crossflow tube and fin design. This is a series of tubes that extend side to side from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer from the coolant to the atmosphere. The inlet and outlet tanks are molded with a high temperature, nylon reinforced plastic. A high temperature rubber gasket seals the tank flange edge. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core. The radiator also has a drain cock which is located in the bottom of the left hand tank. The drain cock includes the drain cock and drain cock seal.
The radiator removes heat from the coolant passing through it. The fins on the core absorb heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.
During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.
Pressure Cap The pressure cap is a cap that seals and pressurizes the cooling system. It contains a blow off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring of predetermined strength, which protects the radiator by relieving pressure if it exceeds 15 psi. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator to collapse.
The pressure cap allows pressure in the cooling system to build up. As the pressure builds, the boiling point of the coolant goes up as well. Therefore, the coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat moves from the radiator to the cooler, passing air. The pressure in the cooling system can get too high, however. When the pressure exceeds the strength of the spring, it raises the pressure valve so that the excess pressure can escape. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the cooling system. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator from collapsing.
Surge Tank The surge tank is a plastic tank with a pressure cap mounted to it. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system. The air space allows the coolant to expand and contract. The surge tank also provides a coolant fill point and a central air bleed location.
During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.
Air Baffles and Seals The cooling system uses deflectors, air baffles and air seals to increase system cooling. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle to flow through the radiator and increase cooling. Air baffles are also used to direct airflow into the radiator and increase cooling. Air seals prevent air from bypassing the radiator and A/C condenser. Air seals also prevent recirculation of the air for better hot weather cooling and A/C condenser performance.
Water Pump The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings. These sealed bearings never need to be lubricated. With a sealed bearing, grease cannot leak out, and dirt and water cannot get in.
The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.
Thermostat The thermostat is a coolant flow control component. It's purpose is to regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber diaphragm. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.
When the coolant temperature is below 91°C (195°F), the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 91°C (195°F), the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, even after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.
Transmission Oil Cooler The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the transmission fluid passes down through the cooler.
The transmission oil pump, pumps the fluid through the transmission oil cooler feed line to the oil cooler. The fluid then flows down through the cooler while the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.
Coolant Heater
The optional engine coolant heater (RPO K05) is rated at 400 watts and supplies 1365 btu/hr. The engine coolant heater operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -29°C (-20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.
Cooling System Description and Operation
Cooling Fan Control
The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage and ignition 1 voltage from the underhood electrical center. The ground path is provided at G102.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan 3 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 3 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).
Engine Coolant Indicator(s)
COOLANT OVER TEMP The IPC illuminates the COOLANT OVER TEMP indicator in the message center when the following occurs:
- The PCM detects that the engine coolant temperature exceeds 124°C (256°F). The IPC receives a class 2 message from the PCM indicating the high coolant temperature.
- The IPC will also illuminate the CHECK GAGES indicator and a chime sounds when this condition exists.
The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the system cools slowly or not at all. This allows the engine to warm quickly.
Cooling Cycle Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Some coolant will then be pumped from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.
Coolant is also pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.
The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.
Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in keeping the throttle body cool.
From the cylinder heads, the coolant is then forced to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or it will flow through the thermostat and into the radiator where it is cooled and the coolant cycle is completed.
Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components:
Coolant The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and clean drinkable water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.
Radiator The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a crossflow tube and fin design. This is a series of tubes that extend side to side from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer from the coolant to the atmosphere. The inlet and outlet tanks are molded with a high temperature, nylon reinforced plastic. A high temperature rubber gasket seals the tank flange edge. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core. The radiator also has a drain cock which is located in the bottom of the left hand tank. The drain cock includes the drain cock and drain cock seal.
The radiator removes heat from the coolant passing through it. The fins on the core absorb heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.
During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.
Pressure Cap The pressure cap is a cap that seals and pressurizes the cooling system. It contains a blow off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring of predetermined strength, which protects the radiator by relieving pressure if it exceeds 15 psi. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator to collapse.
The pressure cap allows pressure in the cooling system to build up. As the pressure builds, the boiling point of the coolant goes up as well. Therefore, the coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat moves from the radiator to the cooler, passing air. The pressure in the cooling system can get too high, however. When the pressure exceeds the strength of the spring, it raises the pressure valve so that the excess pressure can escape. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the cooling system. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator from collapsing.
Surge Tank The surge tank is a plastic tank with a pressure cap mounted to it. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system. The air space allows the coolant to expand and contract. The surge tank also provides a coolant fill point and a central air bleed location.
During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.
Air Baffles and Seals The cooling system uses deflectors, air baffles and air seals to increase system cooling. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle to flow through the radiator and increase cooling. Air baffles are also used to direct airflow into the radiator and increase cooling. Air seals prevent air from bypassing the radiator and A/C condenser. Air seals also prevent recirculation of the air for better hot weather cooling and A/C condenser performance.
Water Pump The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings. These sealed bearings never need to be lubricated. With a sealed bearing, grease cannot leak out, and dirt and water cannot get in.
The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.
Thermostat The thermostat is a coolant flow control component. It's purpose is to regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber diaphragm. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.
When the coolant temperature is below 91°C (195°F), the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 91°C (195°F), the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, even after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.
Transmission Oil Cooler The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the transmission fluid passes down through the cooler.
The transmission oil pump, pumps the fluid through the transmission oil cooler feed line to the oil cooler. The fluid then flows down through the cooler while the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.
Coolant Heater
The optional engine coolant heater (RPO K05) is rated at 400 watts and supplies 1365 btu/hr. The engine coolant heater operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -29°C (-20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.
I respect you but .....you are incorrrect.
With a REAL radiator mine runs 192 (192 t-stat) in 110-115 heat , idling , stop and go , running hard , no matter what the conditions
It never varies more than 1 degree.
The stock radiator is a joke.
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