I saw a friend at a car show Saturday and he reminded me how i solved his overheating problem. Since he had done about everything I could think of I told him to check the coolant. Sure enough, the coolant was almost pure antifreeze. Cheap and easy to check. Just a thought........
Ron

I'm going to run to Home Depot today and pick up one of those laser guided temperature gauges. I'm not running anywhere near full antifreeze. The mix I run only floats about 3 of the 5 balls in my tester (don't remember what that equates to) but is less than a 50/50 mix.

Drove about 15 miles today and stopped at Home Depot to get a infrared temperature probe. It is only 88* out so things were fine. The gauge stayed between "E" and "M" the entire time. When I stopped I left it running and the top tank was 180* and the bottom tank was 166* or so. So I'm getting good cooling across the radiator (I was also thrilled at how well my small trans cooler was working). Maybe it'll really warm up this afternoon and I can try to get it to overheat.

14* drop across the radiator isn't very good. Under the best conditions you'd get around 40 degrees.
If it works, it works. If it's getting hot and you can't see anything better than that, you have a problem with either low air flow or coolant moving too fast.

That was at idle. I think I need an assistant to hold the throttle for me while I check out temperatures.

You should get a high temperature drop at idle. The coolant is moving slow enough to spend time in the radiator dropping temperature.

Is the fan pulling enough at 700rpm to get adequate air flow?

If you haven't changed the pulley ratio and the clutch is in good shape, it should be adequate.

I've been thinking that maybe it was the rad considering I've replaced everything else. Now the data really seem to be pushing that way. I'm going to do a tad more testing today. But no, I have not changed the ratio.

Of course we had rain come through this afternoon and cool everything off. I can't get the t-stat to stay open long enough to do any more testing.

Finally, some data! The top tank is getting to over 205* when it starts to pass "M." The fins are running about 155* and seems very even across all the fins. But the bottom tank is 175* or so. What in the world does that mean?

Bump

175 in means that you are not getting enough air flow or water surface area.

if it cools down while driving at speed it's not enough air flow.

But why would the tubes between the tanks be so cool while the bottom tank is so much hotter?

how many rows does it have?

what are the temps of the back tubes?

there should be some reading differences from the inlet to the outlet.

It should be three row.

I cannot get good readings on the back tubes because there is a fan moving in the way. If I turn the engine off everything soaks to the same temp.

Top to bottom the tubes go from near the temp of the top tank down to about 150* or even lower for some. But the bottom tank is freaking hot.

If the transmission cooler is in the bottom of the radiator that would explain the elevated temps there.

I also have an external cooler after the one in the radiator. The entry temp on it is around 150 and the exit temp is 110 or so. I'm really confused about what's going on.