Odd Overheating issue

[batman420]

Hey Guys i have a rev-d B4 and i have noticed around town cruising the car runs at normal temp, once i am on the open road at 100kph (cruising) the cars starts to warm up, i can control most of the over heating by cranking up the heater full heat and full fan, this is enough to pull the temp back down to normal, once i turn off heater it starts to climb again.

checks so far

the radiator fans work

i have changed the thermostat with a genuine subaru one

it is brand new coolant, the red organic stuff from ripco

pretty sure there are no air locks left.

i have been told to flush out heater core but i dont see how that will help as when i put the heater on max it cranks out the heat, so that tells me there should be no issues with that, pretty much i dont want to remove intercooler again to do this haha cbf

cheers guys

[loner]

Radiator blocked or corroded or both?

[batman420]

drove the car today, the outside temp started at about 10 degrees car ran fine, as soon as i got into the sun the outside temperature went up to 16 then car slowly started warming up.

on the way back to chch it was 11 and the car didnt heat up past normal once, even with a bit of a thrash.

i will test it on the next hot day and see what happens, im hoping it has figured itself out. if not ill give the radiator and heater core a good wash out.

[SpeedySub]

I had some overheating issues, I think mine was an overflow hose that would let air in and then cause an airlock. Next time it over heats check if the bottom radiator hose is hot, Mine would stay cold when it was overheating.

[batman420]

hey speedy sub i checked the overflow hose and there was a split so i fixed that so no more airlocks, i also changed the rad cap as i noticed it wasnt allowing coolant to return to radiator.

went for a drive yesterday up the port hills and it went fine, then drove up major aitken and ended up racing a vr4 it was going good for two mins then started creeping again.

bugger i thought i had it sorted.

bottom hose is hot when engine is overheating

next up i have water pump and radiator to look at.

[SpeedySub]

How did you remove the airlocks? I'm sure theres a page on here that explains the procedure, but i remember that there was something about having to raise the front of the car when removing any air in the system. Will see if I can find it later.

[slystiguy]

Sounds like either a block in the system or not enough fluid... The heater cores are common faults and clog easily. When I cleaned mine it had a bit of gunk in it and this was a car that didn't over heat.

Are you using oil or water? You've checked that the head gasket hasn't gone or beginning to go?

When you filled radiator did you leave the cap off and run the car while burping the system and topping up with more cooland? When I do my radiator stuff I usually manually refill the engine and heater core up to avoid air pockets and then have to spend 20mins burping the system. Also pays to check coolant level on regular basis.