For some reason my heat is not working properly in my 05 Evo, when im driving normal it works perfectly fine when i accelarate hard and then slow down the heat goes away for about 30 seconds maybe a minute and then comes back to normal what could be causing that

 

bump it up

 

does the temp gauge actually drop

 

Coolant low. Have you opened the rad cap? Otherwise its a bad t-stat.

 

check collant!!! it is most likely low. if it is check ur oil to make sure that oil/collant isnt mixed with eachother. If it is it is time for a head gasket..

 

Here is another idea check your vacuum line on your intake manifold... If it has a slight tear there is your problem. Thats what was wrong with mine.

 

thanks i just refilled the coolant checked the thermostat by boiling it in water it does open, i guess ill have to check the vacuum lines tomorrow

 

I hate to point this out but you already knew the thermostat was opening. You can't drive without overheating if it doesn't. However, thermostats can fail in a mode where they open too soon. You'd have to boil the thermostat with a new one to see this.

 

Also, make sure you don't have any air in your system.

 

i changed the oil too and theres no coolant in it going to check over the vacuum lines today it seems when i filled it yesterday with coolant and drove around a bunch of the coolant came out of the reservoir so im not sure if i overfilled it or what

 

hg

 

You can't overfill the cooling system. It is supposed to be completely full at all times. During engine operation thermo expansion will cause some of the coolant to move over to the bottle. After the engine cools coolant in the bottle should return to the engine. The level in the bottle should then have returned to the level it was at the last time the engine was cold.

If the level in the bottle is below the full mark and when driving the level in the bottle increases to where the bottle overflows then he head is lifting and the HG is blown.

 

I might be having a similar problem. When I start up my car, the temp gauge needle would go up like normal, but when I drive it and accelerate, the needle would drop all the way down, then go back up. Would my issue be related to the coolant level?