Car won't reach operting temp

The 50/50 mix should be fine, but you could probably go with something like 80/20 if you really wanted to. My gut instinct says it's the thermostat, but double check to make sure you don't have some air pockets in the system, too. Toss the front end on some jackstands so the radiator fill is the highest point, and burp the system. That could very well be the problem all along, and could save you from even having to change the thermostat.

Car won't reach operating temp

Also check the radiator cap. If the cap is leaking, you will not build up the heat you need. With an open system the max temp you can reach is 212 degrees at sea level. Less at high altitudes. If you are adding small amounts of antifreeze like a pint a week suspect the cap.
Also make sure you have the right pressure rated cap. I believe a 16 psi is correct. If someone put a drastically lower rated cap that could be your problem.
The problem is probably the thermastat. The first one that I bought and I put in my car did not come with the correct rubber grommet needed to seal around the thermastat. I went back and the parts store sold me the wrong grommet. Buying a second thermastat with the correct grommet cured the problem. Also the original thermastat did not have enough of the rubber grommet left to discern how it sealed. The thermastat should have a round rubber grommet around the circumference that makes it fit snuggly back in the cavity for the thermastat.
I hope this helps. I don't want you to go thru the agony I did.

wv109323 said:

Also check the radiator cap. If the cap is leaking, you will not build up the heat you need. With an open system the max temp you can reach is 212 degrees at sea level. Less at high altitudes. If you are adding small amounts of antifreeze like a pint a week suspect the cap.
Also make sure you have the right pressure rated cap. I believe a 16 psi is correct. If someone put a drastically lower rated cap that could be your problem.

Click to expand...

Huh? So if I heat water in a pot (an open system) I can only heat it to 212 deg. F? It'll start boiling at 212 without a doubt, but I can keep heating it beyond that. Now if I put it under pressure, I can raise the boiling point above 212 degrees. The higher the pressure, the higher the boiling point. This keeps the water in liquid form at higher temps so it will continue to do what I need it to do and that's pull heat away from my engine which is something steam won't do. On the flip side, the lower the pressure, the lower the boiling point. Water in a vacuum of 30" hg will boil and evaporate at room temperature. It's one of the reasons for pulling a vacuum on an A/C system before charging it. Any moisture trapped in the system evaporates. But anyway...

Typically if a car has a bad radiator cap or some other reason for loss of pressure, it overheats. It can't maintain the pressure it needs to raise the boiling point and keep the water "wet".

When someone says it's not building heat, it's either a bad or missing thermostat, bad or inaccurate temp gauge, or a bad temp gauge sending unit.

Simple one, it's the thermostat.

Hopefully simple.

I changed the sender and thermostat and I still only reach 140-145 at best on the gauges, but you can just about melt your shoes with the heater blowing on full on the floor. My fuel mileage did increase by 4mpg by changing the sensor. I'm at a loss to explain my gauge reading.

If you aren't getting heat or very low heat on your car, I'd suspect bad thermostat. My previous thermostat would also stick periodically giving me an over heat situation at low speeds.

Yep, check out the vacuum to the heater/ac controls. Make sure the hoses are connected, and there is vacuum available.

If that does not fix it, start checking the vacuum motors to the doors that direct air to different places.