Hi, need help folks!

sorry, I know it’s a common post but looking for some advice specific to my symptoms. I’ll try and keep it brief...

i have 03 wrx Impreza overheating, fan in car blows hot, it only overheats when stationary or stop start driving and cools down when I get to give it some gas. I have tried to burp coolant several times but it’s still happening in rush hour traffic. Oil temp says normal or less than 100deg but coolant will pass 2/3. Rad fans come on when warm, top rad pipes hot bottom pipes cold.

headgasket? - no oil in coolant and no coolant in oil, car drives fine other than overheating and no white smoke from exhaust...

Any thoughts on what it could be would be greatly appreciated.

Thermostat should fail open...

Sounds like airlock or headfasket pressurising system

Thanks guys I’ll Gary burping again and test the thermostat - are they common to fail?

in not I guess sniff test time ��

if if it was thermostat why does it cool when in flowing traffic then stop and overheat when stationary? Surely the hotter it gets the more open the stat should be?

Thanks for the info guys!

Please do do keep it coming!

must admit stockcar I didn’t suspect thermo as it’s a basic bit of kit.

intrestingly I burped again today, got it to normal running temp the put cap bk on and did a quick round the block, as the heating was on it didn’t get past normal running temp but fans didn’t come on! So connected the test plugs under the steering wheel and fans did function albeit the one sounded like it was catching on something I presumed a leaf as I couldn’t see anything and it wasn’t too loud.

also, I confess, I do think I have a small coolant leak on the front somewhere but it’s minor and as I’m keeping the system full and burping I wouldn’t have thought this could be the issue? If it is and I’m a idiot, please feel free to say so but if so can you explain how a slow leak can cause overheating in a full system?

im not mechanically minded but does this indicate anything significant? I’m not sure when the fans should come on? but I think I’m going to get it near to the 2/3 mark tonight and check if they are on then or not...

will keep ya posted, thanks again!

Fan might be catching on the top rad hose under higher revs will leave a small hole we’re you can’t see

usually happens if top rad hose isnt put on correctly check near bend area

will only squirt coolant wen under pressure

Thx Zany, Gave it a quick run, fans do come on but that tick noise is still there driver side under the air intake I think. I’m gunna take it off in the daylight n have rummage. Tired running my hand along the top pipe but couldn’t feel the fan catching it / me.

might call out the aa too for the mobile sniff test

propa love hate relationship with this scooby business

watch this space lol

Maybe pjarvis, I think the pump is down that drivers side of the car, perhaps that’s what’s making the noise. Had cam belt done bout 2 months ago, I hear you should change them together (belt n pump) but i didn’t think it meant it would pack up so soon after if It is that.

Thx stockcar, that’s good to hear, the cam was done by a reputable specialist I woundnt name cuz I don’t want people thinking they have done a bad job. At the end of the day it’s an old car so I guess things like this will arise. I’ll try n find it myself Later today and if not it’s off to the garage where a proper mechanic can inspect it

Well it’s not the fan catching, the fan was hitting one of the wires powering the fan so I have tucked it out of the way. Crawled on the floor and it looks like most coolant is on the passenger side of the front. I’m lost, think I need to get it on the ramps...

Had aa out today, didn’t sniff test but said he didn’t think it was headgasget as no mixing and runs too smooth. Scanned engine bay with thermo cam when overheating and nothing was over 92 n all the pipes n rad looked hot so it’s all circulating. Guage in car was showing 2/3 so he thinks it’s temp sensor knackered. Does any one know what the guage represents on a thermometer? - my norm running temp is just below 1/2 so I guess that’s 90 odd?

Also found error code P0483 - which is a fan rationality error, but I think that’s only on cuz the ecu is telling em to stay on due to the faulty sensor?

in the end agreed i should get a second opinion from a specialist...

good news i guess

I have neglected to mention when aa fella plugged in his ecu reader, he said when hottest part of car was 92 from thermo Scan, but the ecu was reading 108 coolant temp. Can any one confirm if this points at coolant temp sensor?

if so I hear there are 2, do I change both or just one, which one? Argh!

i hear temps are:

93 - normal or at temp (just below half on guage)
98 - hot 2/3
107 - death time, I would imagine this is H on the stock guage

Thx don clark, u think that’s the culprit then?

Thx Don,

did is a blast on way home overflow tank went up about 1/2 pint, kept temp in tolerance with heating on. I guess that’s normal and it will drop down to less than it was in the morn as I’m topping by bout half pint every other week.

when your hg went did you have other symptoms like smokey exhaust, running rough or mixing oil n coolant?

i guess it’s trial n error now, coolant leak n stat then sensor n then, I dunno, take up religion...

None of the above and as said sniff test didn't show anything either.
What did happen is that coolant level sometimes didn't drop in the expansion tank as engine cooled overnight, leaving the header tank low with air in the system.
Finally confirmed after a non stop return trip from Castle Combe to Harpenden and the expansion tank was overflowing and bubbling away.

Ah I see, be nice if these things were easier to diagnose, got sensor n stat on delivery now so hopefully can sort them the weekend. Will keep posting on progress in hope the thread can aid another poor suffering soul!

Fixed! Was thermostat, looks like the old one was a cheap aftermarket one, replace and all is gd now.

10 points to the shreksta

thanks all for your advice, was really appreciated!