225 running a bit warm!!!

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cudamark said:
If the coolant flows too freely, there is poor heat transfer to the radiator/air.
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I feel I have to jump in here because this has been oft-repeated by several people. Plus, another person above is claiming a lower temp thermostat will make the engine run hotter.

I don't see a first-order scientific explanation to how more coolant velocity could give less cooling. That doesn't mean it isn't true, but if true it would be due to some "second order effect" like sucking air into the system or maybe redirecting a jet flow inside the head in certain engines (like the Coanda effect). Otherwise, higher fluid velocity gives higher convective heat transfer and a higher boiling coefficient.

Who am I to comment? A mechanical engineer with graduate degrees who has published many papers in heat transfer.
 
Bill, I think (but don't know for sure) that the implication was that the water would travel too fast through the radiator to take advantage of its cooling potential if the thermostat is removed. This also means that the water going through the block would not have time to pick up all the heat. So when it gets to the radiator it would be a little cooler. However the water would then return to the radiator sooner, and then back to the block sooner. With an unregulated system like this it would seek its own level and the temperature would reach a certain point based upon how the engine was being opperated. In general this temp would be a little low (taking into account the engineering of the system which might see some extreme conditions having a built in safety margin) for the engine to operate properly. The comment was made that the thermostat keeps the engine up to operating temps (also the heater functions better), this is true. What you had to say is also true. Getting into the physics of heat transfer and fluid flow is getting out of the league of most people. The engineering should already have taken take into account friction and heat build up from fluid flow, cavitation, pressure, volume, material composition, fluid composition, ambient temps, and a myriad of other variables. The solution is to figure out which component isn't serving its purpose and repairing or replacing it. It is spring. Maybe there are bugs in the radiator.
 
Btw.....we have had many cars come into the shop with the complaint of "running a bit warm". When checked with a Ratech gun some of them the gauges were faulty and reading high.

How are you reading "a bit warm"? Have you checked it with another device? If with a dash mounted gauge; could it be faulty? Maybe too much resistance in the wire?

Just more to think about.
 
Since he indicated that the temperature is higher than the thermostat setting and that it fluctuates it is unlikely that there is a sending unit problem and that the coolant system is being taxed beyond the capability of the radiator.
 
Hey guys, I have checked it with two gauges and a temp gun all the same temp so I know the gauge is right. I'm going to look more into it tomorrow I'm not giving up that easy!!! The fan pic is on the way!!! BTW what is the timing supposed to be set at for a 1971 225 automatic tranny
 
Check your emission sticker if you still have one. I think the book says 2 1/2 BTDC but I like to run 5 BTDC if it doesn't ping. TDC if you have to, but, don't go ATDC as it will run hot and get worse mileage (as well as having no power)
 
With all this expert knowledge, I have to ask "youall" My '64 Dart 225 -auto trans runs right on mark (a on gauge) except those very hotandheavy traffic days. Climbs towards the out of normal on temp gauge and then cools down when a normal drive speed returns. 180 stat, upgraded to more blades on fan, every thing I am pretty sure is clean and flowing. I have repaired the Rad so many times that I want to replace. Any feedback pro or con on a aluminum. Also any off the shelf suggestions. -Dart Ken
 
Same responses
add a larger flex fan
Clean out your carb.
Make sure you have an overflow tank.
You could possibly switch to a high flow thermostat.
I would not change the low pressure radiator cap.
I would possibly add an electric fan
 
Dart Ken said:
Climbs towards the out of normal on temp gauge and then cools down when a normal drive speed returns. 180 stat
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Without calibrating the temp sensor and gage against a known sensor, we probably don't know what temperature "out of normal" on the gage really is. It could be just 10 F.

One thing to understand is that the thermostat does not control exactly at its setpoint (180 F). The engineering concept is "proportional offset", which you can find in wikipedia or other sources on "proportional control" or "PID", if interested. The higher the thermal load, the more the thermostat must open beyond its nominal position. This requires a higher than normal temperature. Your experience may be normal, based on the simple controller design.
 
im going through similar checklist with my 360 and some other suggestions are to make sure outlet and inlet radiator hoses are not collapsing when you rev the motor. also the sending unit and your temp gauge have to match
 
Slantsixdan is right about the airflow, mine ran hot for a while and I found the problem to be a gasket in the middle of a Chinese built POS!!! carb. When I went to the parts store they said that they could not stand behind it and they did not sell, nor could they find the gasket online.. so they gave me enough material to make two new gaskets.. and the problem was solved....

so in other words, check all of your lines, make sure you carb is on tight.. etc..
 
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