Not Your Average Cooling System Problem

sandfreestyle said:

I went ahead and swapped a stock pump I had on the shelf and a cheap CSF 1-row rad just to test and everything is working the way it should now. Hasn't gotten over 215 after a good long test drive with start and stops at the end. Now I'm wondering if the 4-row rad will have any difference with the stock pump.

Click to expand...

IMHO, 4 row radiators are nothing more than a marketing gimmick. The tubes hide behind each other and do not get sufficient cool air passing over them. In addition, the tubes are too small and easily get blocked.

In the 17+ years I have been on this forum, the only people that are satisfied with after market aluminum radiators are those who buy the high dollar ($400+) units and they all have one thing in common,...two rows of tube each being 1" or thicker. Everyone who bought an OEM radiator are happy with it.

I am a firm believer that a properly maintained OEM cooling system is up to the task of keeping the 4.0L temperatures within working parameters. Although I have not tried the snake oils, I believe that ported thermostat housing, special water pumps as well as many of the thermostats out there are snake oil. The entire cooling system in my XJ is now 12+ years and all OEM with the exception of dual electric cooling fans.

Happy to hear the temperatures are now within the acceptable range.

In 2001 I installed a 3 core copper brass radiator that did not cool as good as the OEM single core it replaced.

Maybe I am in left field here, but I have heard of high flow pumps moving fluid so fast it doesn't have time to cool in the rad... For that reason I use stock replacements on both my xj's with great luck.

Sent from my SM-G950U using Tapatalk

SlowXj said:

Maybe I am in left field here, but I have heard of high flow pumps moving fluid so fast it doesn't have time to cool in the rad... ...

Sent from my SM-G950U using Tapatalk

Click to expand...

No not at all.


If you had a sealed rad (no flow) full of hot coolant, and subjected that rad to airflow, yes, the longer you left the coolant in the rad, the more it would cool. However, if you were to plot that cooling over time, you would find that the RATE at which the cooling takes place is an exponential curve that decreases with the temperature difference between the hot coolant and the air. Put another way - when the temperature difference (delta-T) between the hot coolant and the airflow is large, heat transfer (cooling) initially takes place very, very quickly (almost instantaneously). But as that happens, and the coolant cools, the delta-T becomes less, and the RATE at which further cooling happens gets less and less until the point where the coolant and air are almost the same temperature and continued cooling takes a very long time. This is Newton's law of cooling.


https://www.pirate4x4.com/tech/billavista/Cooling/


So much bad info in this thread.