thermostat
Thread Starter
Junior Member
Joined: Aug 2011
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The tstat blows coolant out, the radiator is newish the granny is leaking but I've kept it up on its fluids. I actually just found a part of my exhaust smoothed ( might be a problem. And I did a compression test yesterday, its all good.
Seasoned Member
Joined: Aug 2011
Posts: 344
Likes: 1
From: California
Year: 1989
Model: Cherokee
Engine: 4.0 i6
There are many reasons for overheating.
Yes, the water pump can be pumping the wrong way. Remember, the 4.0 originally was a 4.2 – with a Vee belt. When they went to a Serpentine belt, the belt turned the pump the opposite way. The impeller was the only thing different. It was reversed so the fluid went the right way. Originally the Serp type pumps were marked with a REV on the front. But through the years since that REV got lost, and rebuilders mixed up the impellers. Most pumps are made in China or Brazil – adding even more confusion. It’s possible to get a Vee type when you need a serp type.
If the wrong pump is used, it will overheat almost immediately! It will overheat the engine, but the radiator will remain cold. Usually within 3-5 minutes.
Always compare the impellers when buying another pump.
If it’s already on the engine, remove the T-stat housing and T-stat. Start engine – coolant should flow out the T-stat well like a firehose.
While the t-stat is out, make sure it has a slot or hole on the flange to let air bleed through. If not, drill an 1/8 inch hole. Put the hole or slot at the TOP when installing.
The belt – serp belts slip – that’s why most use tensioners. If no tensioner, check the tension – where it runs a long ways between pulleys, twist the belt. You should be able to twist it about 90 degrees with effort. If you can twist in more than 90 degrees, it’s too loose. Much less it’s too tight.
Try feeling one with a tensioner to get “a feel.”
A belt that slips will overheat it at higher speeds, especially with the AC on.
Get a laser type infra-red thermometer – Harbor Freight about $30. Handy for lots of things. Measure temps all over the radiator – cold spots indicate plugs in the tubes.
Measure the temps of the heater hoses – in and out – find plugged heater cores.
A stuck T-stat becomes very obvious.
When fully warmed up, rev it and watch the lower hose – if it collapses replace it. That’s the suction side.
Take a perfectly operating system and remove the T-stat – now you have a system that will overheat! The T-stat is a restriction, slowing the coolant down to allow it to transfer it’s heat to the radiator. Without that restriction the coolant goes too fast. Removal will not make it run cooler.
Air is a killer – proper bleeding is critical, especially on the closed Renix system.
Renix - The help you fill it after it’s been open, jack up the rear of the vehicle so the rear of the engine is higher that the rest. Remove the coolant temp sensor at the back of the engine. Fill the system slowly from the overflow bottle – when full, coolant will come out of the temp sensor hole. Let it stand for 5 minutes, try adding more. Replace sensor.
On non closed systems (cap on radiator,) you can remove the front left headbolt to bleed the air out. Use water sealant and torque the bolt properly afterwards.
Be sure the heater controls are set to ON, otherwise air hides there.
Using a lower temp T-stat will not help the engine to run cooler, but it will cause it to run rich, wasting fuel and lowering HP.
A partially restricted exhaust system will also cause overheating – use that infra-red thermometer! Check all along it – where it’s restricted it will be overly hot, then right after that spot it will be much cooler. Constipation!
If a defective head gasket is suspected – check the dipstick for water. Check the oil filler cap – look for brown Mayonnaise looking stuff. Do a pressure test and compression test. Check the exhaust pipe in the rear for coolant!
Check your automatic trans fluid too – a defective cooler can leak. It will turn the ATF milky.
Hope this helps, RRICH
Yes, the water pump can be pumping the wrong way. Remember, the 4.0 originally was a 4.2 – with a Vee belt. When they went to a Serpentine belt, the belt turned the pump the opposite way. The impeller was the only thing different. It was reversed so the fluid went the right way. Originally the Serp type pumps were marked with a REV on the front. But through the years since that REV got lost, and rebuilders mixed up the impellers. Most pumps are made in China or Brazil – adding even more confusion. It’s possible to get a Vee type when you need a serp type.
If the wrong pump is used, it will overheat almost immediately! It will overheat the engine, but the radiator will remain cold. Usually within 3-5 minutes.
Always compare the impellers when buying another pump.
If it’s already on the engine, remove the T-stat housing and T-stat. Start engine – coolant should flow out the T-stat well like a firehose.
While the t-stat is out, make sure it has a slot or hole on the flange to let air bleed through. If not, drill an 1/8 inch hole. Put the hole or slot at the TOP when installing.
The belt – serp belts slip – that’s why most use tensioners. If no tensioner, check the tension – where it runs a long ways between pulleys, twist the belt. You should be able to twist it about 90 degrees with effort. If you can twist in more than 90 degrees, it’s too loose. Much less it’s too tight.
Try feeling one with a tensioner to get “a feel.”
A belt that slips will overheat it at higher speeds, especially with the AC on.
Get a laser type infra-red thermometer – Harbor Freight about $30. Handy for lots of things. Measure temps all over the radiator – cold spots indicate plugs in the tubes.
Measure the temps of the heater hoses – in and out – find plugged heater cores.
A stuck T-stat becomes very obvious.
When fully warmed up, rev it and watch the lower hose – if it collapses replace it. That’s the suction side.
Take a perfectly operating system and remove the T-stat – now you have a system that will overheat! The T-stat is a restriction, slowing the coolant down to allow it to transfer it’s heat to the radiator. Without that restriction the coolant goes too fast. Removal will not make it run cooler.
Air is a killer – proper bleeding is critical, especially on the closed Renix system.
Renix - The help you fill it after it’s been open, jack up the rear of the vehicle so the rear of the engine is higher that the rest. Remove the coolant temp sensor at the back of the engine. Fill the system slowly from the overflow bottle – when full, coolant will come out of the temp sensor hole. Let it stand for 5 minutes, try adding more. Replace sensor.
On non closed systems (cap on radiator,) you can remove the front left headbolt to bleed the air out. Use water sealant and torque the bolt properly afterwards.
Be sure the heater controls are set to ON, otherwise air hides there.
Using a lower temp T-stat will not help the engine to run cooler, but it will cause it to run rich, wasting fuel and lowering HP.
A partially restricted exhaust system will also cause overheating – use that infra-red thermometer! Check all along it – where it’s restricted it will be overly hot, then right after that spot it will be much cooler. Constipation!
If a defective head gasket is suspected – check the dipstick for water. Check the oil filler cap – look for brown Mayonnaise looking stuff. Do a pressure test and compression test. Check the exhaust pipe in the rear for coolant!
Check your automatic trans fluid too – a defective cooler can leak. It will turn the ATF milky.
Hope this helps, RRICH
Pretty much on point.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Except for the coolant flow part and the running rich, wasting fuel and lowering hp part.
http://www.arrowheadradiator.com/14_...utomobiles.htm
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
http://www.arrowheadradiator.com/14_...utomobiles.htm
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
Last edited by djb383; Aug 16, 2011 at 09:45 PM.
Senior Member
Joined: Aug 2011
Posts: 760
Likes: 6
From: Landers, CA
Year: Several
Model: Cherokee
Engine: 4.0
"""""Except for the coolant flow part and the running rich, wasting fuel and lowering hp part."""""
http://www.arrowheadradiator.com/14_...utomobiles.htm
That would be true IF the vehicle was not computer controlled. The PCM is constantly trying to achieve Stochiometric. Power would increase slightly being cooler, but as soon as the PCM detects the air density change, it compensates. With a older non computer systems we used to run them very rich to hopefully get a tad more power. It worked, but emissions were out of sight and gas wasn't so expensive. Times have changed!
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
1000's of people that tried removing the t-stat completely will argue that. Try it yourself!
Sorry, I don't have a "gimmick" to sell or try to fool everyone with. They pretend people add more restriction than the t-stat, then solve it!
Look at their pictures - it's the same as a regular t-stat - just 3 holes instead of 1. Quality T-stats like Stant also have the same thing.
There are lots of products that are sold on the internet with justifications - but ???? Things like magnets for the fuel lines, TB spacers, etc that work on the placebo method.
But believe what you want.
http://www.arrowheadradiator.com/14_...utomobiles.htm
That would be true IF the vehicle was not computer controlled. The PCM is constantly trying to achieve Stochiometric. Power would increase slightly being cooler, but as soon as the PCM detects the air density change, it compensates. With a older non computer systems we used to run them very rich to hopefully get a tad more power. It worked, but emissions were out of sight and gas wasn't so expensive. Times have changed!
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
1000's of people that tried removing the t-stat completely will argue that. Try it yourself!
Sorry, I don't have a "gimmick" to sell or try to fool everyone with. They pretend people add more restriction than the t-stat, then solve it!
Look at their pictures - it's the same as a regular t-stat - just 3 holes instead of 1. Quality T-stats like Stant also have the same thing.
There are lots of products that are sold on the internet with justifications - but ???? Things like magnets for the fuel lines, TB spacers, etc that work on the placebo method.
But believe what you want.
Seasoned Member
Joined: Aug 2011
Posts: 344
Likes: 1
From: California
Year: 1989
Model: Cherokee
Engine: 4.0 i6
Except for the coolant flow part and the running rich, wasting fuel and lowering hp part.
http://www.arrowheadradiator.com/14_...utomobiles.htm
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
http://www.arrowheadradiator.com/14_...utomobiles.htm
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
Dude! I was thinking that too...but I didn't want to go on and on. LOL
Thats why I said "pretty much"
Thread Starter
Junior Member
Joined: Aug 2011
Posts: 89
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Ok well tonight I pulled the water pump, it looked to have some water coming out of the weep whole, and the bearings were bad, but it still spun around so it would have worked fine still, right?
And I took a hose too the heater core hoses and they seemed fine nothing out of the normal, and I took a hose to the other parts and they all seemed to flush out fine. Is their something I need to look for that come out?
Since those things seem all fine im going to pressure test the radiator, not sure it could be my problem, but doesn't hurt to check.
Any more input is greatly appreciated
And I took a hose too the heater core hoses and they seemed fine nothing out of the normal, and I took a hose to the other parts and they all seemed to flush out fine. Is their something I need to look for that come out?
Since those things seem all fine im going to pressure test the radiator, not sure it could be my problem, but doesn't hurt to check.
Any more input is greatly appreciated
Thread Starter
Junior Member
Joined: Aug 2011
Posts: 89
Likes: 0
Originally Posted by rrich
The belt – serp belts slip – that’s why most use tensioners. If no tensioner, check the tension – where it runs a long ways between pulleys, twist the belt. You should be able to twist it about 90 degrees with effort. If you can twist it more than 90 degrees, it’s too loose. Much less it’s too tight.
Try feeling one with a tensioner to get “a feel.”
A belt that slips will overheat it at higher speeds, especially with the AC on.
Hope this helps, RRICH
Senior Member
Joined: Aug 2011
Posts: 760
Likes: 6
From: Landers, CA
Year: Several
Model: Cherokee
Engine: 4.0
He He - a squealing belt is yelling at you "I'm slipping!"
That alone can cause overheating. It usually manifests itself at higher speeds.
When the pump's seals are bad enough for it to leak out the weep hole, they are bad enough to let air in when it's cooling off (it's under a slight vacuum then - normally drawing coolant from the overflow bottle.)
That alone can cause overheating. It usually manifests itself at higher speeds.
When the pump's seals are bad enough for it to leak out the weep hole, they are bad enough to let air in when it's cooling off (it's under a slight vacuum then - normally drawing coolant from the overflow bottle.)
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
...........
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
1000's of people that tried removing the t-stat completely will argue that. Try it yourself!
Sorry, I don't have a "gimmick" to sell or try to fool everyone with. They pretend people add more restriction than the t-stat, then solve it!
Look at their pictures - it's the same as a regular t-stat - just 3 holes instead of 1. Quality T-stats like Stant also have the same thing.
There are lots of products that are sold on the internet with justifications - but ???? Things like magnets for the fuel lines, TB spacers, etc that work on the placebo method.
But believe what you want.
http://stewartcomponents.com/tech_tips/Tech_Tips_3.htm
1000's of people that tried removing the t-stat completely will argue that. Try it yourself!
Sorry, I don't have a "gimmick" to sell or try to fool everyone with. They pretend people add more restriction than the t-stat, then solve it!
Look at their pictures - it's the same as a regular t-stat - just 3 holes instead of 1. Quality T-stats like Stant also have the same thing.
There are lots of products that are sold on the internet with justifications - but ???? Things like magnets for the fuel lines, TB spacers, etc that work on the placebo method.
But believe what you want.
Post up some viable links stating that "not using a t-stat will directly cause overheating". I enjoy reading/learning fact, not fiction, and like they say 1/2 of what's on the Internet is BS.....just gotta figure out which 1/2 is which.
I've never experienced no t-stat running hotter than with a t-stat when all other variable were equal. I've never experienced cooler coolant temps in 100 degree weather using a cooler rated t-stat. The t-stat controls minimum temp only.
Now, if one is talking about driving around on a 100 degree day without a t-stat and the next day is a 80 degree day and the t-stat is re-installed......well duh....it'll run cooler with a t-stat on a 80 degree day vs a 100 degree day, with or without a t-stat.
Last edited by djb383; Aug 17, 2011 at 08:39 AM.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Senior Member
Joined: Aug 2011
Posts: 760
Likes: 6
From: Landers, CA
Year: Several
Model: Cherokee
Engine: 4.0
Agree - the t-stat controls minimum temperature - you have that right.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
Last edited by rrich; Aug 17, 2011 at 09:28 AM.
Member
Joined: May 2011
Posts: 167
Likes: 0
From: Charleston SC
Year: 2000
Model: Cherokee
Engine: 4.0L
Not to throw another wrench into the party, but I had a stubborn overheating issue which turned out to be pinholes in the rusted metal hose connection that runs out the top of the water pump. I could see a little collant pooling in the A/C compressor mounting where it had been spraying out. Of course the thing was so rusted that the only way to replace was with the water pump as well. Now it's all good.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Agree - the t-stat controls minimum temperature - you have that right.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
Again, I've posted 2 links (not my opinion) discussing coolant flow rate....where's yours?
CF Veteran
Joined: Feb 2010
Posts: 12,367
Likes: 23
From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
Agree - the t-stat controls minimum temperature - you have that right.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
When the t-stat is removed totally, coolant can flow much faster. When it flows too fast, it doesn't get cooled by the radiator as much. The engine can overheat easier.
TRY IT!
Ask any radiator shop!
If it made it run cooler, or decrease the chance of overheating - don't you think the engine manufacturers would make the hoses slightly bigger to let the flow go faster?
Why do they put in a t-stat that's somewhat restrictive when it would be so easy to use something less restrictive?
Or is it a plot to make vehicles overheat?
If making the coolant flow super fast made it never overheat, don't you think someone would build it that way - then they'd certainly have a great advertising ploy - "IMPOSSIBLE TO OVERHEAT!"
The t-stat is restrictive - look at the shape - the area that the coolant passes through is small compared to the opening where it sits.
Now look at what that site sells - very little difference if any. Flim flam!
Power - when the engine does not reach the temperature the PCM is expecting, it assumes it's still cold. The PCM adds more fuel, thinking it will help with driveability - stumble, sag etc. Mileage does not go up, but it does go down. Horsepower does not go up either.
And, if it's very much cooler than expected, the PCM limits timing advance - also lowering HP.
I think you must be confusing having the air/fuel charge cool rather than the combustion chamber being cooler to increase power. If the charge is cooler, it's more dense, it can hold a tad more fuel and air.
When it hits the hot surface of the chamber that mixture starts to expand - even before the spark event.
The difference between the water temp being 170 degrees vs 190 or 210 degrees will not make any appreciable difference - remember the combustion temperature is closer to 3000 degrees - the 30 or 40 degree water temp difference is minute by comparison.
. if the water is flowing too fast through the system it will not have time to absorb the heat from the cast iron engine block and cylinder head. What you see on the temp gauge is the WATER temp, not the actual engine temp. Think of it this way, you can touch a hot frying pan quickly without getting burned because you hand was not there long enough to absorb too much heat. Now rest your hand on a hot frying pan for five seconds and see what happens, your hand absorbed more heat and you got burned. It works the same way with a cooling system, the water needs time to absorb heat before it flows to the radiator. A cooling system with a high anti-freeze to water ratio will run hotter too because the anti-freeze/coolant does not absorb heat as fast as water.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Not to throw another wrench into the party, but I had a stubborn overheating issue which turned out to be pinholes in the rusted metal hose connection that runs out the top of the water pump. I could see a little collant pooling in the A/C compressor mounting where it had been spraying out. Of course the thing was so rusted that the only way to replace was with the water pump as well. Now it's all good.