coolant flow question

[Blase]

I did not read this whole thread. But in general removing the T-stat only adds a band aid to an off-raod buggy. Hear me out.

As stated early in the thread taking a WORKING t-stat out extends the time to get the engine up to working temp. So by doing that in a buggy that doesn't drive for longer periods of time it may look like it fixed the problem.

So if you pull the T-stat and have no problems some people consider that "fixed". To each his own.

Really that is a sign of other problems IMO. Either some blockage somewhere in the system, A bad T-stat, a weak or failing water pump, Hoses that are not sized correctly, or in the case of a lot of Off Road Buggies a need for a better fan/ fan shroud or a bigger rad.

What you do with the rig and what you are doing when it's over heating tells you A LOT about what is really wrong with your cooling system. unless the T-stat is bad removing it is not really addressing the real issue. It may seem to have fixed it but sooner or later you will over heat again.

Hope that helps.

 

[jeepxj]

bill vista is the man for this kinda stuff:

http://pirate4x4.com/tech/billavista/Cooling/

 

[ddawg16]

bill vista is the man for this kinda stuff:

http://pirate4x4.com/tech/billavista/Cooling/

jeepxj...thanks for the link.....I just can't figure out why people find it so hard to believe that faster water flow in its self will NOT hurt cooling....

Myths
For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.

The myth is stated as either:

Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance.

The reason the myth is so persistent, is that: a) without knowledge of fluid dynamics and laws of thermal conduction it does make a kind of intuitive sense and b) it is based on a tiny kernel of truth, but that kernel of truth does not explain the overall system behaviour and so, interpreted out of context, leads to a completely erroneous conclusion.

For those that think no t-stat causes over heating I'm going to suggest that it's one of 3 things.
1. Cavitation of the water pump
2. Without the restriction, the temp sensor is being bypassed and as such is giving a false (too high) reading.
3. The radiator cap is on the high side and the unrestricted flow is causing a greater pressure at the cap and thus causing it to vent.

I would bet that 2 & 3 are the causes in a majority of the time.

Now....about that water wetter....my neighbor swears by it....but I have yet to see any 'real' scientific results. As I said before...I think the reason people see an improvement with WW is because they typically go to 100% water...which does a better job of cooling than a water/glycol mix.

It turns out that plain old distilled water has the highest specific heat of all liquids commonly used for coolant. Water has a specific heat of 1 - meaning one pound of water can absorb 1 BTU for a temperature increase of 1° F.

A 50/50 Ethylene Glycol / water mix has a specific heat of 0.5, meaning it takes only 0.5 BTUs to raise the temperature of 1 pound Ethylene Glycol / water mix 1° F.

A 50/50 Propylene Glycol / water mix has a specific heat of only 0.3.

Therefore, it takes twice as much heat to raise a pound of water 1° F than a 50/50 Ethylene Glycol mix; and over three times as much heat to raise a pound of water 1° F than a 50/50 Propylene Glycol mix.

Ultimately, what this means is that straight water can carry away 50% more heat than 50/50 Ethylene Glycol mix and 70% more heat than 50/50 Propylene Glycol mix per degree per unit volume.

So what I think happens is people can't get good cooling with water/anitfreeze...flush the system...put in water and that one little bottle of ww....what do you know...it runs cooler....must be the water wetter....

No snake oil for me....

 

[omr]

The fact that most of the problem cars or bikes i have dealt with only over heated when idling makes me believe cavitation was not a problem ..

If they were over heating while moving and the engine speed was higher then i would be more likely to suspect cavitation..

If i am wrong here i would like some one to explain to me why these vehicles operate in the normal temperature range when they have a thermostat but over heat with out one ..

 

[ddawg16]

The fact that most of the problem cars or bikes i have dealt with only over heated when idling makes me believe cavitation was not a problem ..

If they were over heating while moving and the engine speed was higher then i would be more likely to suspect cavitation..

If i am wrong here i would like some one to explain to me why these vehicles operate in the normal temperature range when they have a thermostat but over heat with out one ..

How do you know it was over heating?

Did you even read the billavista article?

 

[omr]

How do you know it was over heating?

Did you even read the billavista article?

I read the quotes you posted ,it seemed like you were saying the cause of the overheating was cavitation or the temperature sending unit was in a place that didnt get coolant flow..

Considering all the vehicles i mentioned only over heated at idle none of what you posted seemed to explain any thing ..

 

[ddawg16]

I read the quotes you posted ,it seemed like you were saying the cause of the overheating was cavitation or the temperature sending unit was in a place that didnt get coolant flow..

Considering all the vehicles i mentioned only over heated at idle none of what you posted seemed to explain any thing ..

The quotes I put in were just the 'tip of the iceburg'.....you really need to read the billavista article. There is one section that explains in detail about the high side of the radiator and how it relates to pressure and flow.

 

[omr]

The quotes I put in were just the 'tip of the iceburg'.....you really need to read the billavista article. There is one section that explains in detail about the high side of the radiator and how it relates to pressure and flow.

ok i will but im watching a movie right now so i will look at it later, but if the temperature sending unit isnt getting flow then that means other parts of the motor arent either..

Unless i read some thing in that article that explains this better i am not seeing alot of hope in the sending unit theory ..

 

[omr]

I gotta be honest with you ddawg16, when they wrote ten paragraphs on pressure drop i lost interest in reading the rest..

I mean cmon man, the guy says it would take 5 miles of hose to overwhelm a 10 psi pump , if thats the case then it really has no real bearing on the conversation of automotive cooling systems..[and wouldnt the amount of horse power of the pump play a part in that equation? rhetorical question]

I would have read the whole thing if i didnt think it was going to be full of fluff like that ..