Car overheating...can't figure it out.

[SinCitySVT]

Ok, here is my problem...
My car started overheating a few days ago. the problem seemed like a sticking thermostat, so I changed it. it ran fine after that. I also noticed my heater wasn't blowing hot, and that got better after changing the thermostat and bleeding the coolant system. the next morning, it started overheating again. I can feel the inlet hose from the engine to the radiator getting hard to squeeze, while the outlet hose has almost nothing running through it, and the overflow tank is full and under a lot of pressure. after shutting the car off, the overflow tank drains pretty quickly, and the temperature gauge falls to just past center. i keep adding water and colant, and it keeps happening. i don't know where it is all going, as I see no visible leak. i took the car into ford thinking it may be a block in the radiator or possibly the water pump. Ford called me back today telling me i have a blown head gasket. They say they did a block test (?) and saw that there was air in the system and that is why they believe there is a blown gasket. The engine oil looks normal, I don't have any water coming out of the exhaust, and the engine is not missing or detonating. Any opinions on what is happening? I really don't think it is a head gasket. PLease help.

 

[blkvertterm]

You have an air bubble in the system and you need to burp it. Every time I change my coolent the same symptoms you have said start.

This usally happens because the overflow cap can no longer hold pressure. I believe it is a 16 psi cap. Water vapor escapes while you drive and you never notice the level go down until it is to late. An air bubble gets in there and it is a bitch to get out sometimes. Even though the overflow tank appears full the system is half empty.

If the engine is hot and you take the cap off pressure will still come out. With the car engione off as the car cools down you will see the water level in the overflow tank drop suddenly and then boil back when it hits the hot engine. When this happens put water in there or coolent. Eventually you will have enought fluid so the system will start to flow and you can burp all the air out.

You can search the word "burping the coolent system" here. You should find many post on the subject and I would also suggest searching a bad radiator cap. It is very common for the spring or seal to go bad in the OEM cap.

I learned a little trick when there an extremely low coolent level, but you are at your own risk at this. If you put a hose with running water over the thermostat area, and bottom hose, and radiator after the engine is off you will notice the all the coolent availible in the system will be drawn into the engine and heads. The overflow tank will drain into the engine very quickly. Also if you put a hose with running water over the top hoses the same thing will occur. When the water gets sucked in refill the tank and repeat the process until the system can be burped and starts flowing. I would be very careful not to put water on the metal of overheating engine. I hope I don't need to explain why.

I hope this helps.

 

[fastmustang70]

if that doesnt it do it is a blown head gasket am a 100% sure let me know Ron

 

[phillySVT]

Is you fan turning on? Check the Fuse to see if it is blown.

 

[ShelbyGuy]

mod motors dont lose head gaskets like a pushrod engine.

its air in the system.

burping is a process, not a one time procedure.

 

[03cobrazzz]

you need to take the plug out of the pipe on the right side by the supercharger snout and leave the radiatorcap tight on.start the car anlet it warm up.fill in coolant and water as it goes down till no bubles coming up any more.then reinsert the bolt and let the car cool down till cold and recheck coolantlevel.when you have a lot of bubles after a while you can check with a co tester most repairshops have one and can tell you thxt it is a headgasket.try bleeding it first and see that the bubles go away.

 

[SinCitySVT]

thank you all for the responses. I did bleed the system. I filled the cross-over tupe instead of the radiator cap. I took it to a different dealership and they said it was the overflow cap. They replaced it, bled the system and said it was fixed. I drove home and it happened again. Air is still getting in the system somehow.

 

[Juruense]

Perhaps you have a crack or pinhole leak in the coolant resevior. Also possible is that the thermostat is sticking.