Technical Radiator cap and getting hot

Twenty8. I know I sure appreciate the help. This is a great site and many have talked me through many issues!

 

I agree Dan. @FrozenMerc sounds like the go-to guy with this.

Thanks.

 

Everybody throw everything at the wall & see what sticks or what is commonly known as internet diagnosis ...LOL. . ( that's a joke people !)

 

I'm not sure this is accurate. There is a ton of data on the net that you can find with a search that supports the idea that an increase in coolant flow rate will improve the rate of heat transfer from the engine to the atmosphere. It has a lot to do with temperature differentials, the rate of heat transfer is better with a greater difference in temperatures. There are engineering formulas to calculate this, for instance, here is a calculator you can experiment with, just change the flow rate and observe the effect on the temperature rise in the output:
http://www.nessengr.com/technical-data/water-cooling/

This is a frequent topic of discussion on computer nerd forums, as computer nerds, like hot rodders, deal with overheating problems on their computers. While there are obvious differences between water cooling a computer CPU and a hot rod engine, the same basic theories of heat transfer work the same on both. Here is a good thread on the subject, check out post #7 from Barryng:
https://www.overclockers.com/forums/showthread.php/78055-Flowrate?s=

You might also check post #11, and #12 on that same thread.

This next one is interesting, a discussion on thermal nuclear reactor cooling system design:
" Wall (coolant side) temperature is defined by the equation

Tw =Tc+q/α

where Tc is the coolant’s temperature, q is the heat flow density and α is the heat transfer coefficient. This is the only parameter that can be controlled by completely physical means and one that is the greater the better. It increases with the speed of the coolant, and also with the flow turbulence degree and the channel’s inside area. The most straightforward way to increase α is to speed up the coolant flow. " (emphasis mine)

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/coolant

And finally see this thread on a tri five discussion board, see post #57 from Chevynut:
https://www.trifive.com/threads/overheats-on-highway-cool-at-low-speeds.49850/page-3

The bottom line is, the faster you can cycle the coolant, the better or more efficient will be the rate of heat transfer.

 

Here's another paper on the topic that shows how increasing the coolant flow rate increases the coolant temp as it leaves the engine, i.e. the increasing the coolant flow rate increases the rate of heat transfer from the engine to the coolant
https://www.researchgate.net/public...m_of_an_ICE_under_Nucleate_Boiling_Conditions

 

There is a vast misunderstanding of how thermodynamics, as applied to an ICE, or other heat generating appliance with a liquid-to-liquid, or liquid-to-air heat exchanger.

Unfortunately, it is repeated as gospel truth on many internet forums.

In my tenure working for General Motors, I authored authored 10,000 pages pertaining to the designs of cooling systems, for ICE, electric powertrains, propulsion batteries, and onboard computers for autonomous vehicles.

I can tell you with authority that @Blues4U is correct in what he has posted.

 

I was told there would be no Math!

 

We just got way above my pay grade......... Let's hope the OP is sitting down when he reads the latest input.

 

Hey , let the really smart guys add to the confusion !

 

I have always had the most consistent results results in a performance motor using a flow restrictor in place of a thermostat.

 

You're correct about just flipping the existing fan but early on, International, Caterpillar and other heavy equipment manufacturers used a fan that drew air through the radiator and over the engine. It worked, but it was very uncomfortable for the operator in warm weather. In cold weather, the operators would put canvas shrouds down the sides of the engine compartment and benefit from the warm air blowing at them. The problem with that was the amount of trash that would accumulate in the radiator. They tried changing the fan blade direction and found that the engines ran just fine and the radiators stayed cleaners with the reversed air flow. To this day, if you walk in front of the radiator on heavy equipment, you will find hot air blowing out at you.

Truckers in extremely cold climes used winter fronts to keep their engines at correct operating temps. The simplest, usually a tarp or piece of cardboard in front of the grille, required a lot of stop and go to adjust for existing conditions. Mechanical louvers in front of the radiator required constant monitoring of the engine's temperature and adjustment. As late as the '80's, I was driving trucks with louver systems to control air flow to the radiator. Some trucker noticed the heavy equipment operators working in the extremely cold weather and tried the reverse flow fan. It worked.

 

This is true, but it is the fan blades themselves which are reversible. Each blade is mounted on a swivel and is spring loaded into a locked position, but can be turned to reverse the direction of the air movement if desired. Blower fans tend to reduce dirt and debris build up in the radiator.

 

Blue, You are not wrong. An increase in turbulence does improve heat transfer, and that is why I prefaced my point with the last sentence stating that changes in turbulence and pressure drop across the pump will have an effect on the heat transfer rate. However, I will argue that the effect is relatively small, 5% to 20%. (Of course that is not a small effect to the operator if a 10% gain keeps your coolant from boiling over in traffic). Heat exchangers are governed by the equation: Q=m*Cp*(T1-T2).

Q = Heat Transfer Rate
m = mass flow rate of the working fluid
Cp = Constant - Specific Heat of the working fluid
T1 = Inlet Temp
T2 = Outlet Temp

If m goes up, the temp difference has to go down to maintain the same heat rejection rate. Increased flow also comes at a cost of more power required to drive the coolant pump and greater pressure drop across the pump, both of which add additional heat energy to the coolant.

This is the fun side of engineering. We create equations and models to explain real world test results. Then we realize that the math gets too complicated and end up modeling the horse as a sphere to make the math easier!

 

Thanks @alanp561 , I didn't know that about heavy equipment and trucks. Always good to learn something new.
I will still stand by my comment that you cannot fit the fan backwards in the OP's situation. Well, you can I guess, but it will not make any difference to the air flow direction..........

 

I guess that is the same principle that is applied to ceiling fans ?
You move a switch on the housing and the fan makes air flow down,,,,,and the other way ,,,,( reverse ),,,makes it flow up .

Wait a minute,,,,,,there must be something wrong with this theory ,,,LoL .

I grew up using D8 dozers,,,,,,in hot summers,,,,and freezing winters,,,,,I was 14 when Daddy put me to work ,,,,it was a Cat D8,,,,series 15A,,,about a 57 model I believe.
Pony motor start,,,,,cable actuated blade .
In the late 70 s here,,,I remember it being froze to the ground a few times .

The fans on heavy equipment push air forward,,,because they only move about 2-3 mph .
Not a lot of added cooling like driving down the road .

And yes,,,,we had a reversible fan,,,,you literally had to unbolt it .
But,,,it really felt good in the winter,,,,just like a heater blowing on you .

Just like a ceiling fan,,,or an electric fan on a car ,,,,depending on the rotation .

Tommy

 

@Desoto291Hemi and others , unbolting a mechanical fan off the pulley and refitting it backwards will not make the airflow go in the opposite direction. The pitch of the blades will be the same and the rotation direction is the same, therefore the air will flow the same way.

The ceiling fans turn the opposite direction when you move the switch. This will reverse the airflow.

Fitting an electric fan backwards will reverse the flow because you have essentially reversed the rotation direction.

Go stand and stare at your mechanical fan for a while...............

 

Twenty8 ,
Lol,,,,,had you going there didn’t I,,,,I’ll bet you called me every kind of name in the book .
You’re right,,,,,,the blades stay the same,,,,only reversing direction will reverse flow .
Also,,,I didn’t mention all in my post,,,,,he didn’t flip the fan,,,,,he actually had a replacement that was reverse flow for the dozer .
Daddy would swap the fans in winter or summer,,,,two different fans entirely .

Lol,,,,,,had to get a little dialogue going,,,,,you guys down under are alright.

Tommy

 

So, how long did you stare at your fan before it all made sense.....?
I simply looked at my ceiling fan, then stood on my head and looked again...........

 

Lol,,,,no my ride at the moment is an OT model,,,,,only has an electric.
And besides,,,,too cold out to do anything,,,,LoL .

Tommy

 

90* here today. Thinking about a swim...............

 

Oh yeah,,,,you guys are in the middle of summer down there .
Man,,,,I can’t imagine a heat wave at Christmas time !
Either way,,,,,Merry Christmas,,,,,,and a happy New Year !

Tommy

 

Perth, in Western Australia, is expecting 107* for Christmas day!!! Where I am in the east, we are expecting a chilly 73*.
Merry Christmas and a happy and healthy New Year to you guys too.

 

To keep things on track, it's the type of weather down here where you want to make sure your thermostat and radiator system are working to their full potential..........

 

I stalled the 180 NOS Fulton siphon stat. Ran just water. Gauge went to 240 but thermal gun read 193 at the water pump housing. So either have a bad Sendor or gauge. Water was circulating so stat was at least partly open. The manual references the stat should open at 160-165 and be fully open at 190. The stat I took out originally was a 165. I’m thinking on staying with the 180 I have in there now. Thoughts?

 

According to the manual, the Fulton siphon has built in bypass ports and it has to be aligned a specific way. Going to check that today and maybe replace the sender for the gauge

 

The 160° T-stat specs were published at a time when "permanent" glycol coolants were rare, or at least kind of expensive. The common anti-freeze solutions were alcohol based, which tended to boil off quickly and lose freeze protection. A 180° would be preferred, I think. Most OEM had bumped them up to 190° by the late 1950s for improved engine wear and tolerate extended oil change intervals. There's this tendency for people to think engines should always run as cool as possible, and that isn't really true.

 

Huh? Water will not boil at 185, no matter where you are, or whether you have cap on the radiator.

 

Truck64. Yeah I’m sticking with the 180. Just added coolant and ran it. Gauge hit 240 but heat gun at water pump housing was 190-205. Bad gauge or sender is my next guess

 

flynbrian48. I think I have bad gauge or sensor. Gauge just read 240 but heat gun at water pump housing was 190-205