I Have a 94 wrx and this morning when driving it to work I noticed the temperature gauge was through the roof. I immediately went into slow mode and limped the car to work. As I was driving it was getting worse so I decided to take a look at the forums to see if I could identify the problem. I found the threads about the head gaskets and just immediately thought it was that. But any way I have changed the thermostat and checked the radiator for blockages. I noticed also no hot air was coming out the vents when it was hot. All the signs pointed again at head gasket until I took the car out for a quick blat and found that the harder I drive the car the cooler it gets also hot air starts to come through the vents at this point, so it appears to do the opposite of the head gasket problem. I have been told it may be the water pump which is only gaining enough pressure to push the water round when it revving high. What do you guys think? Another note is that when the car thinks it hot when not moving the radiator is stone cold Please Help? Thanks in advance

 

If you get a coke bottle and cut the bottom off it nad use insulation tape to wrap around the neck so you will get a good fit , remove the rad cap and fit the bottle into the hole , the bottle will act as a header tank , 1/4 fill the bottle and start the engine ( make sure the bottle is secure ) when engine up to temp rev it and watch the water level , if water pump correct and good circulation you should see the water level drop on revving then rise back up when returning to idle . Also keep an eye on the water for bubbles rising up through the water as this may be a sign of head gasket starting to leak .

 

At the least you have an air lock.
Put the heater to "Full Hot" Remove the radiator cap on the header tank (that sounds Irish but you know what I mean) Top it up. May as well check the expansion tank is to level at the same time.
Start the engine and let it idle to warm up. This may take ten minutes depending on ambient. As the water warms, the contents of the header tank should show reasonable movement/flow but no little gas bubbles. Blip the throttle a few times.
The top and bottom hoses and radiator core should be warming as the temp guage starts to read normal. It will fluctuate a little during initial warm up.
Feel the end tanks which should be warm on both sides.
With water temp normal and blower fan on you should have hot air.
If not you still have an air lock or the head or head gasket is pumping gas into the coolant.
You could go to a friendly MOT garage and ask them to put the gas analyser probe above the open header tank to check for combustion product/gas in the hot air/steam from the header tank. If there is more than a trace of HC then sorry but you have head/gasket issues.
Some motor factors also sell a kit for checking the coolant for products of combustion. Basically it is a chemical you add to some fluid from the heade tank and observe any colour change.

 

Thanks for all your advice guys.

 

Thanks again for all your help. It did turn out to be the water pump so thank god it wasn't the head gasket