Car overheating...heater blows cold air...then car cools down and blows hot air

[eurodeseo]

After the car has warmed up and I turn the heater on, I get cold air. As I leave the heater on the engine begins to overheat until it reaches a break point somewhere near the "H", at which time the temperate gauge goes down to normal and I get hot air from the heater.

I felt all the hoses and they all felt warm. I drove the car w/ the heater off and it stayed at a normal temperature range for quite a while until I stopped the car, at which point the car began to slowly overheat.

I thought thermostat...but wouldn't that either be stuck open or closed? I shouldn't all of a sudden get hot air if it's the thermostat. Do you think a radiator flush and fill will fix it? I can't remember the last time I had it done.

[Haleiwa-Brando]

It does sound like the thermostat. Do you have any air bubbles in your cooling system? That will cause spuratic behavior also.

[eurodeseo]

I'm not sure if there's bubbles. Would those be taken care of with a flush and fill?

[Haleiwa-Brando]

You take car of the bubbles when you fill up the radiator. You fill up the radiator until it tops off then you turn the car on with the radiator cap off. Next, while it idles, periodically squeeze the radiator hoses and refill the system as all the air is worked out of the cooling system. As the car starts to warm up, the water/coolant will expand. I do it for about five minutes, then turn the car off. and keep topping it off until the coolant system is full.

If you do have air in your coolant system, it will make pockets through the system and get trapped. As the coolant system warms up and the water expands, preasurizing the system, it will thus pressurize the air trapping it. Air will pressurize more than water since it is a gas. For the coolant system to properly work, it's important to have all liquid in it.

[eurodeseo]

And that's safe to do? It won't go spewing coolant all over the place?

[Haleiwa-Brando]

Originally Posted by eurodeseo

And that's safe to do? It won't go spewing coolant all over the place?

yes.
no.

[eurodeseo]

Awesome. Thanks for your quick responses. I appreciate it

[itr1244]

beating on the dead horse.

my car's doing same thing.
did you ever find out the problem ?

please help me?

mine does exact same thing except my temperatre gauge stays at normal temp.
but my car feels really hot. specially the IM

[itr1244]

did you fix this yet?

[Haleiwa-Brando]

ITR1244: How many miles does your car have? Are you running straight water or a mixture? OEM radiator or aftermarket? OEM thermostat or aftermarket? OEM fan switch or aftermarket? OEM head gasket or aftermarket?

[itr1244]

Originally Posted by Haleiwa-Brando

ITR1244: How many miles does your car have? Are you running straight water or a mixture? OEM radiator or aftermarket? OEM thermostat or aftermarket? OEM fan switch or aftermarket? OEM head gasket or aftermarket?

my car has 60,000 ish miles on the chassis and the motor now has around 250 kms.

-redline water wetter and some water and some anti freeze
-civic 1/2 size rad
-oem thermostat
-oem head gasket

nothing has been changed on my cooling/heating system.
well my motor was sitting out for about 3 weeks before we started putting things together

i got new thermostat coming but i have a feeling that's not the problem

[Haleiwa-Brando]

Hmmmm. I heard that water weter stuff was a gimic. Tested and proven.

Your car is turbo charged or something? Why the half size radiator? Right there using an OEM radiator you have reduced your cooling capacity in half. If your going to use a half size radiator go with a dual core with aluminum end tanks.

Have you ever flushed the cooling system?

[JDM Factor]

50/50 water wetter and water works. Or it atleast dropped temps in the shifter karts by 10 degrees

[itr1244]

Originally Posted by Haleiwa-Brando

Hmmmm. I heard that water weter stuff was a gimic. Tested and proven.

Your car is turbo charged or something? Why the half size radiator? Right there using an OEM radiator you have reduced your cooling capacity in half. If your going to use a half size radiator go with a dual core with aluminum end tanks.

Have you ever flushed the cooling system?

my car's n/a but i am using an-r standard header



it had no problem before i took my motor apart. heat was fine. car never over heated.

i flushed system when i installed everyhing back up.
well i empted it and filled it again and bleeded it enough times

[b00sted_hatch]

the same thing happend to my moms supra. it ended up being her head gasket after we changed everything in the cooling system.

[itr1244]

hum i am pretty sure i put the head gasket the right way.

it's just been replaced

[b00sted_hatch]

hmm..maybe your rad or maybe just a simple thermostat

[itr1244]

it's so weird cuz it was working 100% fine until i did my motor and nothing has changed to my rad/cooling system
wtf

[92TypeR]

Make sure your heater core hoses are routed the correct way. Inlet takes water pre-thermostat and the outlet is post-thermostat. Reversing them can cause the symptoms you described.

[itr1244]

Originally Posted by 92TypeR

Make sure your heater core hoses are routed the correct way. Inlet takes water pre-thermostat and the outlet is post-thermostat. Reversing them can cause the symptoms you described.

umm.. heater core hoses?

can some one please describe how this looks like? but picture would do 1000 words.

i am confused.

[itr1244]

are you reffering to those two hoses on the bottom right?

[92TypeR]

yes

[itr1244]

i have never disconnected those hoses from my fire wall
and the short one goes on the back and the longer one goes on the front.
it's impossible to get those 2 mixed up i think .

[Black R]

Originally Posted by itr1244

are you reffering to those two hoses on the bottom right?

I noticed that the 1998 helms for the itr has the diagram WRONG for the itr.....!

[itr1244]

no Way?

can someone with 01 itr can help me out?

grr