Overheating problem - Help

[lowandy]

So ive got a 1 year old waterpump and thermostat from subaru, replaced the radiator cap but its still got a weird problem.

Ill be driving around fine then the temp will start to rise so i pull over and the overflow bottle is overflowing and the radiator cap is cold.

Im suspecting a block somewhere in the system?

Im currently flushing it the block with a hose and have removed the radiator to flush it aswell.

Testing the thermostat in boiling water and its opening fine.

Also when flushing the radiator there was some oily residue in the water which could be headgasket leaking?

Thanks

[Guest]

It may be blown head gasket which is causing it to overheat. If your confident the thermo is fine and radiator not blocked etc may be bad news. Isit consuming coolant?

[Koom]

Sounds like a headgasket. Once you've re-fitted the radiator, try running it up with the radiator cap off. I make a little funnel with some thick rubber hose so that it has a small head of pressure as well (helps to bleed the system).

And keep a very careful eye on the open header tank. I reckon it'll keep blowing bubbles out i.e. headgasket failure

[lowandy]

So i put the thermostat in boiling water and it opened up but then seemed to close after maybe 5 mins when the water was still hot. (Didnt know temp because thermometer was working properly)

I put everything back in and tried to bleed the cooling system. It was sitting at normal operating temp with the heater on max but still blowing coldish air - which i thought was suspect. Temp continued to rise slowly above half. Had the radiator cap off and touched the water and was cold but top rad hose was hot + bottom hose cold. So thermostat not opening correct? or possibly thinking about it now it could be water pump since its not pumping hot water into the heater core?

I will remove the thermostat and run it without it to see if thats the problem

[Rosssub]

Sounds more like a blocked heater core? Try putting the garden hose through it and see if there's any flow getting through.

The thermostat should first start to open at 76-80c then be fully open at 91c.

Edited June 30, 2014 by Rosssub

[lowandy]

Yea mate flushed from the top rad hose, then from the hose going into the heater aswell as just the radiator. And flushed them all for roughly 5 mins jst to be sure.

I dont know if this is something to note but i flushed from the top rad hose and was flowing out the waterpump alot but then i started the car and left the hose on there was less water coming out the waterpump aswell as water was flowing back out the top rad hose-- if that makes any sense to anyone?

[Scoobydoo]

If you get a TK or leakdown test done at your mechanic, that will tell you if it's headgasket or not. Would at least take that out of the equation, instead of guessing.

[lowandy]

So today i pulled the thermostat out and redid the coolant.

Pros-

Doesnt overheat anymore = suspect faulty thermostat?

At idle with heater on max it seems to blow coldish but once driving the air heats up....any ideas?

When i first got the car around 2 years ago the heater was bypassed already so that could mean that somethings wrong with the heater

[Koom]

Thermostats are cheap. Replace that to see what difference it makes as your one sounds like it's being a bit dickey.

[lowandy]

Ive removed it completely for the time being to see what difference that makes.

Still not sure about the heater core but might just leave it as it is since its not causing any problems