Hot area in radiator

W

Wildturkey

Junior Member
Mapping of the temperature of my radiator with infrared thermometer reveals an area of about 10 square inches of surface area with temperatures much hotter than the remainder of the surface. Today after eighteen miles with outside temperature of 94 degrees the temp gauge was steady at 195. After a long hill at 40 mph the temp went to 205. It will lose water with multiple long hills. After returning home today mapping showed 180 degrees at top of radiator with a 10 degree drop top to bottom but in the hot area the temperature was 260 to 300. How can I have an area hotter than incoming water? I recently had the radiator boiled with no help and last week I had it rodded. The radiator tech reported no obstruction at rodding. What can I do next?
 
Get a "block test kit" from NAPA or a good auto parts store. Blue liquid in a clear plastic cylinder that you sniff the filler neck of the radiator with. If the blue turns yellow, you have exhaust gases in your coolant, due to cracked head or block, or bad head gasket.
 
A freshly rodded out radiator should not be running 195*-205*. If it were my car, it would be going back to the shop. Sounds like it may be time for a new core. Over the last 80 years, it is likely that your fins have detached themselves from the tubes which then they won't dissipate heat properly.
 
I had the radiator sniffed for gases. Timing adjusted multiple times, head torqued but not removed for inspection, GAV setting tried in multiple positions, spark lever placed in different positions, and new pump. The radiator is two year old three row repro. Should I remove head for inspection despite normal sniff test or proceed with recoring or replacing radiator?
 
I wouldn't think a 3 year old radiator should be in bad shape.
Any chance a mouse nest is in the engine or radiator?
Stuff happens when the radiator is off.
 
I washed the radiator and block with dishwashing detergent followed by a week of vinegar. I then removed hoses and washed and backwashed the block with one of those plumber's expanding and pulsating clog removers with no trash produced. The radiator man found no obstruction at rodding. I feel reasonably comfortable there is no obstruction.
What explains the area of marked increased temperature in the right mid portion of the radiator? Can cavitation occur in a radiator? I don't understand the physics of cavitation but I read that cavitation in the block can result in areas of increased temperature. If my radiator has a structural defect of some sort, could there be cavitation with local increased temperature which cancels the cooling effect of the rest of the radiator? You clearly see that I am "grasping at straws".
 
Does the "hot area" of the radiator have the same finish as the other parts. In other words when you look at the radiator does it have the same finish (same paint, same level of gloss)? The IR therometers are all based on an assumed emissivity value, which is a measure of how well a surface can radiate heat away from itself. The emissivity depends upon the coating. If you have access to a temperatue probe (HVAC technicians usually these) you might try actually measuring the surface temp of the radiator at several locations. Just a thought..... For the difference you are noting you could probably discern the temperature difference with your hand as it is warming up (before it gets too hot to touch) just to verify the IR readings.
 
Sounds like some issue with the measurement rather than real temps. If the water temp truly is 300 degrees, its not water anymore! I would try a different thermometer to see if there are problems with it. When you say you are "losing water", at what level does it stop? Mine will lose water until it reaches a certain level in the radiator tank, and then stay the same for months. I add a quart of 50/50 once a year.
 
I agree with eagle. I don't see how it's possible for the coolant to get warmer as it progresses through the radiator. There are seven sources of heating I am aware of--conductive/radiative/convective transfer from something even hotter, chemical reaction, compression of gas, phase change of vapor to liquid or liquid to solid, friction, nuclear fission--none of which I can conceive of applying here.

Steve
 
Last edited:
The texture, color etc of the surface of the radiator appears equal throughout. I will attempt to find a temperature probe and check the temps to see if the difference suggested by the infra red instrument is true. I have to add no water if temp stays under 205 but on a recent tour in 95 degree weather we encountered about five miles of steep hills. Temp guage went to 210. I stopped and added two quarts of water. I am filling just over baffle.
 
You must log in or register to reply here.
Back
Top