Cooling System Problem

[courtenay]

Decided to start a new thread on this one. My problem started with the fan not coming on until the temp gauge was just below the red line. I have replaced the temp sensor in the rad, replaced a faulty t-stat (it was stuck open), replaced the water pump and checked my temp gauge against one that Narfire kindly sent me. So I'm pretty sure all that is OK.

Since the fan works off the temp sensor in the rad and the gauge works off the temp sensor in the block, I have to assume that the water is not circulating properly. I would think that if it was, the temp would be the same throughout the system, or at least fairly close.

So what am I missing?? What would affect the fluid circulation like this and what would anyone suggest I do next? Also, the fan does come on before the gauge redlines and the engine does cool down. It also runs cooler when I'm actually on the road as opposed to running the thing in my garage. So I'm assuming I'm not going to do any serious damage to the car unless the bloody thing does, in fact, redline.

[So Cal Mark]

circulation issues could be due to a restricted radiator, Check the temp across the radiator core with your IR temp gun

[courtenay]

Mark - there's not a huge difference in temp across the rad. Top right - 140; top left 130; bottom right 172; bottom left 161.
These were taken with the temp gauge at about 195 with the car running - so continuing to warm up. When the gauge was about 2/3 of the way between 190 and the warn - the right side of the block was 215; left side 168 and the head was 180.
The interesting measure was the lobe of the t-stat connected to the water pump - about 300 deg. The lobe leading to the lower rad hose was about 180.

[Zippy]

I'm no expert but it sounds like your thermostat isn't opening.

[courtenay]

The thermostat is new, and it is opening as the lower rad hose is about the same temp as the upper. Also the fact that the rad is hot both top and bottom.