Car has been running hot, figured I would flush the cooling system and replace thermostat and gasket. Made sure to put thermostat in correctly (bought OE thermostat 195 degree). Car still running just as hot as before.
No changes have been made since it started running hot. Timing is set at OE spec. I have a shroud, and yes one half of the fan sticks out of the shroud. The weather can't account for how much hotter its running. If my understanding is correct, water pumps don't fail (other than making noise) because they are driven off the engine. Any ideas? stock 351w fmx

 

What temp is it running at now compared to what it used to run at?

 

Run a second auxillary gauge and check it. If its not acting hot/driving hot I'd say its the gauge going bad or not reading right.

 

I have used two separate thermometers, both readings are the same. I just used my infrared gun. The thermostat housing read 203 pretty consistently and the radiator read about 195. After I closed the radiator cap, the temperature crept up to 206ish at the thermostat housing and up to about 200 at the radiator. I don't know the exact temperature it was running before, but the gauge now reads into the danger zone and it did not before. I thought it might be the temperature sending unit, but it seems to be consistent, plus I already replaced it so i don't know whats going on.
I am left with the radiator I guess, but using my hand to touch the fins there wasn't any cold spots.

 

After letting the car cool down for 30 minutes, I decided to run a test by removing the thermostat altogether. Yes I am aware of the idea that doing this can actually make the car run hotter due to not allowing the fluid to cool down before it exits the radiator. Well the car ran cooler, but hardly at all (EMPHASIS on hardly). After a ride around the block, no change at all (seemed the same as when I had the 195 thermostat in it just before).
My uncle (a ford mechanic for ~25 years) and I believe that something must be clogging the radiator. When the thermostat was out, at idle the flow inside the radiator was not very good at all. It almost looked like swirling or sort of bubbling. By increasing the rpms, it got better, but still the flow wasn't that great. I am assuming the radiator isn't flowing properly due to blockage. I know it could be blockage in the block or even possibly the heads, but I hope its the radiator. Any ideas?

 

So....couple things.

Stock the car came with a 180 thermostat IIRC.
Having a reading of 200-205 at the housing and then 195 in the radiator...sounds like a coolant system working just fine to me.

The water pump is mechanical so flow increases as RPM increases.

Add a second gauge with actual NUMBERS on it so you know what you are running at cruise speeds.

 

Sounds like the perfect opportunity to get a 3 or 4 core radiator and never worry about cooling problems again. People have no qualms about getting excess horsepower, but excess cooling capacity is not a cool (bad pun? ) thing to have. Sure makes those July 4 cruises go by without incident though.

 

Dodgestang: It seems like every source tells me something different about what the OE thermostat is supposed to be. But like I said previously, I can basically rule out that it was the thermostat causing problems, because the t-stat that was in there before the 195 was a 180 and it was not old. I checked to see if it was sticking, but it seemed to be functioning fine. Plus when I ran the car without a t-stat the improvement was extremely marginal.
I obviously know that the water pump is driven off the engine thus as rpm's increase so will flow. But I do know that you should be able to see some crossflow at idle. My car had essentially none at idle. At increased rpm's it was better, but not sufficient.
I don't have a gauge permanently hooked up to the car, but with infrared gun, digital water temp gauge, the gauge cluster, and my experience driving the car since this has started I am sure it is running too hot. The power feels different, and my shifter is actually heating up pretty noticeably (never happened before, and yes the fluid levels are all good).
I went ahead and bought a Champion 3 core aluminum off ebay, after reading some good reviews from people here. Let's hope the installation is straightforward!

 

Ok so I have an update. I just installed a Champion 3 core aluminum radiator. It helps keep the temperatures down on the freeway, marginally, but the engine is still heating up quickly around town. Does this only leave an internal problem (aka blocked coolant passage or blown head gasket) ? The heads don't have that many miles on them (like 15-20,000 maybe) and the bottom end has 95xxx. This is really frustrating

 

Sounds like its working fine to me. 200 at the housing and 206 at the top of the radiator....dialed!

There is one thing you can do to verify that is it is indeed working.

Measure the T stat housing again AND measure the temp at the top of the rad right by the inlet hose AND measure the temp at the very bottom of the rad right by bottom hose

If you see something like
Tstat housing=200
Top of rad = 206
bottom of rad = 170

Then there is no problem.

-Gun