How do I put antifreeze back in???

[Compaq888]

I was changing out my engine coolant temp sensor and I lost half a cup of antifreeze from the engine. Not half a quart, but half a cup. I do have reservoir for antifreeze. Can I just pour half a cup of antifreeze in the radiator or even the reservoir???

[Matt Timion]

I was changing out my engine coolant temp sensor and I lost half a cup of antifreeze from the engine. Not half a quart, but half a cup. I do have reservoir for antifreeze. Can I just pour half a cup of antifreeze in the radiator or even the reservoir???

It's my opinion that you'll have to add alittle more and bleed the entire system, which is probably the easiest thing to do right after using your seat belt.

Then again maybe the reservoir will make it work. DUnno.

[MetroMPG]

i always just add it to the radiator. if the radiator is full because the air pocket is on the other side of the thermostat, i run the engine with the rad cap removed until the thermostat just opens (you can see the coolant start to move in the rad). usually the radiator level will drop then and you can add what you need to replace. (but don't wait for things to get HOT - the coolant will start to spill out.)

[rh77]

i always just add it to the radiator. if the radiator is full because the air pocket is on the other side of the thermostat, i run the engine with the rad cap removed until the thermostat just opens (you can see the coolant start to move in the rad). usually the radiator level will drop then and you can add what you need to replace. (but don't wait for things to get HOT - the coolant will start to spill out.)

I agree -- any interruption in the coolant loop may require an air bleed. When I installed the block heater, I lost more than 3/4 of the coolant and couldn't find the bleed-off valve as mentioned in the instruction kit. So the rad was half-full and reserve tank was full, but the block jacket was empty after hooking everything up. I was nervous that I was going to crack the block or some crazy stuff, but I ended up getting some advice from a friend who knows engine repair, and he said to warm up the car, shut it down, and bleed the system through the rad cap CAREFULLY (I wore protective clothing in the process: gloves, long-sleeved shirt, etc - steam burns more than liquid) -- then repeat the process until coolant only is released. It felt like there was a lot of heat coming off of the engine and thought the gauge wasn't accurately representing it, but it worked out. Then the cleanup began...

[Compaq888]

I just lost a little because of the sensor. I went to Pepboys and they gave me the same directions as everybody else. To just add to the reservoir. Hopefully when I go driving today i'll start noticing a difference. The old sensor had a different color plastic cover and it had white spots all over the the metal rod that goes inside the engine.

[DaX]

If it's just a little you'll probably be fine topping off the reservoir. After the engine heats then cools, the vacuum in the system will pull the extra coolant back in.

Air bubbles suck though. When I installed my turbo on my VX, I was doing backflips thinking I had a blown headgasket and it was only air in the coolant system.

[JanGeo]

Usually there is a bleeder valve high up in the cooling system to let the trapped air out - loosening a heater hose helps if they are high up - but heating and cooling should purge the air pocket - and high revs will move the air through the system and it should be trapped in the radiator to leak out the overflow hose to the reservour but loosening the radiator cap will help as long as the seal to the reservour is maintained. The temp sensor is usually mounted at the exit of the coolant near the thermostat and will NOT indicate an overheated engine if there is NO COOLANT circulating to carry the cylinder heat to the sensor.