I have a 2001 Pontiac Sunfire. I just replaced the thermostat because car was overheating. Now, I fill the reservoir with water and, I will drink it all. The heat will work until the reservoir is empt

Do you check the lower hose for pressure after you've topped off the coolant? Good pressure top hose and no pressure lower hose may indicate a flow problem with the radiator itself. Try flushing it out. The coolant loss might be caused by loss during driving if it's forced out the radiator cap or overflow bottle. I would definitely get the radiator tested. But first try a new radiator cap, they should be changed every two years anyhow and one that can't maintain proper pressure causes all sorts of problems.

I will try that kenF. And Js08016, how would you pressurize the cooling system?

The water has to be going some where! http://www.amazon.com/Mityvac-MV4560-Radiator-Cooling- Pressure/dp/B003V9L05G/ref=sr_1_1? ie=UTF8&qid=1448345967&sr=8- 1&keywords=radiator+pressure+test

Would a parts store such as Advanced Auto have on of those? Full_Of_Regrets

Yes. I don't think he minds me answering for him. You can buy or rent

Another thing, how would one go about about "burping" the system?

@nagini, park the car facing uphill if possible, remove radiator cap and insert a large funnel that has coolant in it and run engine. Don't let the funnel run dry.

@KenF there is no radiator cap, it goes just into a reservoir.

I am flushing the radiator now, the water is very dirty. Like a blackish color. Any ideas?

Even when it gets up to running temperature, the top hose still doesn't have pressure either.

If anybody is able to text, it would be faster to reach me that way. My cell pho e number is 1(615)971-4891. Please text me, or call me.

From your comments it really seems like your radiator is plugged up, corrosion or gunk. Try flushing it alone. If it's coming out blackish it's not a good sign. If you can't get good flow through the radiator it's time to replace it.

@KenF I was told it was the head gasket and the water was gong into a cylinder and out of the exhaust.

Because that is a very expensive repair I would have another shop/mechanic look at it to confirm that, or do a couple simple tests yourself. Visually inspect for coolant in the crankcase and/or a white exhaust plume. It can be hard to spot coolant on the oil dipstick, so you might have to drain a little oil into a jar and let it sit for a while, the coolant and oil will separate. Keep in mind not all leaky head gaskets let oil/coolant mix. Then try a compression test on each cylinder, Bar makes some products for this, see: http://www.aa1car.com/library/how_to_fix_leaky_head_gasket.htm , You can use NAPA block tester to look for exhaust gases in the radiator fluid as well. (however I'm no fan of Bar's head gasket treatment, it can gunk up an engine and coolant system.) If you have to replace the head gaskets you're looking at 1000-1500 if you shop around. The repair will probably cost more than the car is worth. Again, try: 1) NAPA block tester, 2) oil/coolant check, 3) leakdown test. Then decide how expensive a repair this car is worth.

All I need to pay for the head gasket fix, is $122 for the gasket set. I am friends with alot of mechanics at a shop so they will fix it for free. But there is also white exhaust plume as well.

I just found out that my water is coming back out of my reservoir. Any ideas?

Please reply and happy thanksgiving to everybody.

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Is anybody still following this? If so, I done a cylinder compression test and all 4 are right at 120. Car still won't take water in. No pressure is building on any hose. It is just pushing the water back though the reservoir. Please help.

No, I haven't. I still have the pressure tester for the cylinders. How long are you supposed to crank the motor to see how much compression it has?

Do you know why my water would be black?

Alright, will do man. Thank you.

Okay, if any of you still follow this. It has brand new head gasket, etc. It is still ovheating, and still no heat. Please reply.

I have been told that it may be water pump. Thoughts?

I don't know who your mechanic is, but they should have eliminated the chance it was a bad water pump before jumping to replacing the head gasket. Did they at least test to see if there was any actual problems with the head gasket?

No sir, I am having to do all of this with my buddy. We know quite about fixing vehicles it is just this one in particular. But I done a cylinder compression test. And it wasn't great. The old head gasket was bad though.

I just replaced my water pump and it still doesn't want to circulate water correctly. I know what the f*** it could be.

I meant to say "I don't know what it could be" sorry to the confusion.

Anybody following this still?

Is anybody still following this? I have changed radiator, and head gasket, it worked just fine for a couple days. Now it has started overheating again, heat works the whole time. But water still comes back out of the reservoir.

Also, New water pump.

Somebody please respond. I have been 2 months without my car, I am hoping for a fix soon.

Go to https://m.youtube.com/watch? v=2beknOfKVGg to see my problem.

@Nagini - I'm feeling ya. if you find anything that works please update. I'm going through the same thing with my 2000 sunfire (doesn't deserve to be capitalized). I know in fact we put Barrs stop leak in because someone told us it was a leak. But after we drained the radiator to make sure there was actually fluid in it (it was just water in there at this point and drained clear), and refilled it, my husband accidentally found out that the water was coming out of the overflow hose.This is driving us crazy - actually we don't dare drive anywhere further than our local walmart and O'Reillys. BTW we've checked fuses, cleaned a wasps nest off the radiator fins, checked the hoses for actual water flow/pressure, and before that, we drove around with gallon jugs of water just in case it ran dry. After reading countless threads, I'm starting to think I'm getting a new vehicle with my tax refund.

@Lynne: The cooling system was just air locked. Take top hose off, fill block with coolant, then fill radiator with coolant. I filled my block with coolant by putting a garden hose in the metal rail then filling it. Try that and see if that helps.