That is it my car hates me

[TRIPLE-GREEN]

Ok, Some of you have talked me off a ledge before regarding this problem so I thought I would rather then listing the car on Craigslist and hoping for the best come in and talk it out.

This is a 1973 Doge challenger with a 318 w/ a 4brl intake and stock insides.
Over the past year or more I have had endless problems with my car overheating. It all started when I removed the old fan and installed a HHR fan. I had issues with wiring, issues with the pump and I thought I had about worked this crap out. The fan which kept shorting out with the jegs fan wiring kit I bypassed so that it ran all the time.

Recently I had replaced everything one day while the car was hot I did the one thing everyone tells you not to. I opened the radiator cap. Don't try this hat home kids. The car which was running hot had no movement in the coolant in the tank. Wow I thought to myself I have a 195 degree thermostat I think it is bad. I didn't check to make sure I just yanked it. Put it back together with nothing and ran it. The car ran cool as Ice. until I found out here that that is bad. So HERE WE GO AGAIN!!
   I removed the coolant and installed a 180 degree thermostat. A few days have passed and I took it out after installing something else and the car started to get warmer then I thought it should after less then 15 min of driving. I get back to the house and shut it down. About 5 minutes or less later I come back out and turn on the power. Like I expected the temp gauge was now about half way. I wanted to make sure it was not the gauge so I checked it with a lazer temp gauge and it red high. I don't remember exactly what.  I kicked the car back on and the temp didn't really drop. I checked the flow in the radiator again by safely removing the cap and nothing the water was not cycling at least not even close to what it was when I had the thermostat out. This is the second thermostat I have installed that didn't seem to be opening.

I watched an install video to make sure I was putting the thing in correctly and I was. So I am stumped. I don't know why a car that had no history of over heating before I started working on it is now always over heating when I install the correct parts. (the car does run smooth with good power and no smoke.)

This is now the second one I have installed that has not opened. I know it is not the gauge.   

[Jamiez]

Well....for a quick easy test....you can put a thermostat in a pot of water and heat it until the thermostat opens...you can use a laser gauge or other thermometer to verify they do actually open at the correct temperature.
 That will at least rule out the thermostat being stuck or just a bad unit.

[brads70]

Water pump ?  I don't know about small blocks but there are differences in impeller designs in big blocks. Some are better than others. I too have the HHR fan and it works great even with a 451" stroker  putting out 550-600 HP?

How are the hoses? Just wondering if they are collapsing when  hot?  How is the rad? Any crap blocking the tubes that you can see?

[Strawdawg]

two good suggestions above...throw the thermostat in a pot of water and start heating the water up...if you have a cooking thermometer you can monitor temp and see if it begins to open around 175 or so and be fully open by 185.   Also remove the cap and make sure the tubes are not plugged up with junk on the ends.

If the thermostat is opening, the upper radiator hose should be firm and hot......another way to check thermostat opening

[Super Blue 72]

   Both hoses I think should be hot if all is flowing.  Feel the radiator for cool spots and hot spots, an indicator that the tubes in the radiator may be blocked in some areas.

I remember in auto mechanic school the even mentioned about water pumps where the impeller is sliding on the shaft and not circulating, but I do not think that is your case because you took out the thermostat and you saw flow so the impeller is working.

Any air in the system?

[4Cruizn]

What kind of radiator are you using?  I would of probably used a 160* thermostat.  Do you have a high volocity water pump?  How old is it? 

[Jamiez]

How squishy are the radiator hoses?  If they are really soft it is possible for a pump to exert enough pressure that they collapse and restrict flow.  I suppose it's also possible one of the hoses could have some sort of blockage?  You might want to pull them and check.

[4Cruizn]

I think testing the thermostat in hot water is a good idea

[Chryco Psycho]

The impellor could be loose on the water pump shaft , I would pull the water pump , there are 6 & 8 blade units too

[Rich G]

Most small blocks run cool. I'm a bit confused reading your post. You say its running hot but you open the cap and see no movement. If it was running hot the water should be pouring out the top. Stick a meat thermometer in the rad if you don't have a rad. thermometer and see what the real water temp is. You say the water flowed without a thermostat so its safe to say the pump works and the rad isn't clogged. It might not really be getting hot.

[cudabob496]

drill 1/8 inch hole in flat spot of thermostat, so air can vent from system when filling.
How about a radiator and engine coolant flush.
got a good shroud?
I highly recommend the inexpensive aluminum radiators from Summit, or elsewhere.  I had a big
Mopar 3 core, fairly new, but car ran real hot when above 90 outside. The Alum radiator lowered avg operating
temp by about 20 degrees.

[wiging19]

My small block ran hot after I changed water pumps.  It was too years later that I notice the extensions on the previous water pump I didn't install on the new one.  I asked a friend who repairs mopar's for a living if I should put it back on.  He said the reason my car ran hot was because my fan wasn't close enough to the radiator/inside shroud to create enough air on the radiator to cool it properly.  I also had collapsing hoses on the bottom part of the radiator.  Bought a new hoses for the radiators with wires inside to prevent collapsing and put the extension on the water pump.  Car ran a lot cooler to the point I had to put back in the proper thermostat since I put in a 160 so it won't run as hot.

[cudabob496]

timing off a lot can cause overheating.

A 160* thermostat is really not going to solve an overheating problem.  Just means the
thermostat opens earlier.  If the radiator is undersized, or whatever the problem might be,
the car will still overheat, until problem identified and fixed.

My idle is set at 1400 in neutral. In gear, its about 1100.  Keeps the water pump pushing more water when at stop lights.
Also helps my alternator put out better. When hot outside,and I'm at a stop light, I slip in in neutral.

If your idle is around 600 or 700, then your water pump ain't pushing much.

[TRIPLE-GREEN]

Water pump ?  I don't know about small blocks but there are differences in impeller designs in big blocks. Some are better than others. I too have the HHR fan and it works great even with a 451" stroker  putting out 550-600 HP?

How are the hoses? Just wondering if they are collapsing when  hot?  How is the rad? Any crap blocking the tubes that you can see?

Timing is right on, 3 year old radiator, New hoses, New Performance Water pump, without the thermostat the temp is to low and the water flows like a rapped through the radiator. I have replaced everything trying to trouble shoot this one issue. I did know how to check the thermostat to make sure it is opening. But I  at the fact I have to drain and take this stupid car apart one more time. Has to be done I know. I just don't get why this car is rejecting thermostats.

[TRIPLE-GREEN]

Most small blocks run cool. I'm a bit confused reading your post. You say its running hot but you open the cap and see no movement. If it was running hot the water should be pouring out the top. Stick a meat thermometer in the rad if you don't have a rad. thermometer and see what the real water temp is. You say the water flowed without a thermostat so its safe to say the pump works and the rad isn't clogged. It might not really be getting hot.

I am starting to think you may have a point! I will do this before taking it apart one more time.

I did get a thermostat that had a hole in it to release the air. I will try running it one more time and see if I can check the heat more carefully before ripping this thing apart again.