KatiGirl

Hi, hope you can help! It got cold here in Big D yesterday and I discovered the heat wouldn't heat. Blower is fine, just cold air. Then this morning on the way to work I noticed the temp gage was high, then it made two wild swings up to the danger zone and back. I made it to work-- only a couple of miles, but now what? I can walk to Race Trak and get coolant at lunch, will that solve the problem or at least get me to the shop?

thanks! K

Red River T

I changed my coolant last Sunday getting ready for this cold snap and when I first ran it, the temp got high and did that fast swing up to 260. I had an air bubble trapped in the engine and even though the radiator seemed like it was full, it wasn't enough. I removed the temperature sending unit and then added more coolant to the radiator to push the air out. (Some people claim they can park it facing uphill, or pull up on a curb, to add more coolant and that will get the air out.)

The engine temperature started behaving after that, but I found out that I don't have heat. I'm assuming there is still air trapped in the heater. I hope I can get it out tomorrow because I want to go to Fort Worth Friday night. Brrrr!

stevesxm

it needs coolant which will solve your immediate symptom but far more critical is that you have to find out where your original coolant went. take the radiator cap off COLD ( cap on the RAD... not overflow tank ) start the car , fill it up , let it idle with the cap off , heater on and let it warm up and keep topping up until gage is normal. never open the rad cap when its hot and I am talking about the cap on the rad itself... not the overflow tank. don't drive it until you get coolant in it... not even a little bit.

dave1123

Hey Katigirl, are you still there? What did you find out?

dave1123

Hey KatiGirl, are you still there? What did you find out?

KatiGirl

Hi, and thanks to all who posted! I've been out of town on business with sporadic email, and of course forgot my forum login Here's the followup: I walked to Racetrac after work and got a jug of 50/50 coolant and added to the completely cold engine while turned off, through the radiator cap opening, till it got up to the neck of the filler, as indicated in the user's manual. Closed everything up and started it, then with much gurgling and swishing waited while it warmed up. I guess it had gotten fatally low on coolant and that bothers me, since I didn't notice a catastrophic event (like major puddle on the garage floor). It must have been pretty close to that low for awhile. the temp gage sat right on normal and didn't budge. For good measure I stopped again at the store and added more coolant to the overflow vessel. Does that ever flow INto the radiator, or just out? not sure, but not critical at the moment. It got me home and safely in the garage, and the cabin heat returned. So that must have been the core refilling. I feel like I really dodged the bullet of my own inattention to fluid level for good measure when I'm back home I'll take it in to be checked. It's time for an oil change anyway and I want them to be sure the seals are good.

So thanks to all who posted! I appreciate your help and so far it's ok. My dad taught me to not drive without coolant, so glad you echoed that

thanks!

Kate

dave1123

Okay, here's how the reservoir works. When the radiator is full and the overflow reservoir is on the full line, there is normally no air in the system. As the engine heats up, the coolant expands and pressure forces this "extra" coolant into the reservoir. When the engine cools off, this coolant is sucked back into the radiator. If you look at your rad cap, you'll see a large gasket and spring on the outer part and a small valve with a light spring in the center. The large spring holds system pressure to prevent boiling and the small valve opens easily so the expanded coolant can return to the radiator. Usually when a rad cap fails, it's the little spring in the center. If that little valve doesn't seal, there will be no pressure and the coolant will boil at 212*. Steam pockets form and your gauge will shoot up to 260* and back down as coolant refloods the sensor.

My advise? Replace the radiator cap. Keep an eye on the coolant level in the reservoir. If you have to keep adding coolant, you've got a leak somewhere.

stevesxm

kati.. do a couple of things... when the car is cold ... and i mean dead cold from sitting for at least a couple of hours , take the rad cap off and start the car. add any coolant if nec... turn the heater on inside the car and let it warm up and idle until the temp gage gets normal and you can see coolant moving around in the rad... let it do that for a bit then top up if nec and close it up. when you system was low originally and you refilled it i notice you put the cap on before you warmed it up. what that did was potentially trap air in the sytem that had nowhere to escape to. leaving the cap off until the sytem gets fully warm and circulates for a while allows the system to purge any trapped air. the coolant recovery tank is just that... it captures any coolant pushed out by excees pressure and returns it by a reverse suction process as the system cools off. it is not how you check the level or add coolant. i reccomend you go to a shop you trust that has a coolant system tester and have the system pumped. they out a little device that looks like a bicycle pump with a gage on the rad and pump a bit of pressure into the system. if the gage goes up and then falls , then there is a leak somewhere and if you are lucky it can be seen running on the ground when they pressurize the system. its a cheap test and tells you a lot. throwing a new radiator cap at it for the 6 bucks it costs is never a bad thing to do either... but find your leak if there is one. you were very good to see the gage swings and catch the issue before it did damage ( we hope ) but like all symptoms , just adding coolant didn't fix anything. get to the root of the coolant loss and fix that. its important.