technolaser

A plea for help! Impreza 2006 non-turbo.

I have an intermittent overheating problem which only happens every 2 or 3 weeks. It can happen when travelling on a freeway or standing in the traffic. The temp very quickly rises to 110C and may then go up and down.

I had the exact same problem 2 1/2 years ago. At the time they replaced the following: 3 X thermostats, 2 x fan relays, radiator, temp sensor and water pump. My garage said they couldn't find the problem and told me to take it to an auto-electrician. At the end of a full day's work (charged for a day's labor) they said it was the thermostat! Anyhow, it behaved fine until 2 months ago.

I've just replaced: thermostat, radiator cap, and fan relays with no improvement. The system has been "burped" following the regular recommendations.

There are no bubbles that might indicate a head gasket failure but I have ordered a kit to test for this just in case. The level in the header tank isn't dropping.

Please guys, I'm desperate for ideas.

jaygsi

iTrader: (46)

Has the water been flushed out and replaced? Sounds a head scratcher. What's a freeway?

technolaser

Antifreeze replaced twice.
Freeway = British for highway!

Don Clark

You do realise this is a UK based forum ?? and that we Brits would use Motorway - Freeway is more US..........

technolaser

Sorry!

jaygsi

iTrader: (46)

There's another thread with similar issues, but with a WRX might have same issue.

technolaser

Thanks Jaygsi, I'll look for it.

JDM_Stig

iTrader: (3)

How are you proving the temp you are seeing on the dash, sounds like a it could be a erroneous reading if you have changed the whole cooling system
Id be tempted to run it up to temp and compare what the ECU is actually seeing and using a infra red thermometer see if they tally, the dash is rather vague so find a cheap OBD lead, grab some free software like Romraider and see if they tally up,
It could be a faulty CTS sending random info to the dash, I know a few that have had this, as Ive changed a few CTS`s for members on here when this happened,
Hope this helps.

technolaser

Thanks JDM Stig.

I have an OBDC reader and it shows the same occasional jumps to 115C. It normally runs between 91 and 102.

I have narrowed it down to usually happening after travelling for 5 to 10 minutes at 100kph and then stopping the car. If I jump out and check I see that the radiator fan is running, top and bottom hoses are hot, and that there's some pressure in the hoses but they're not hard.

If I turn the engine off for 2 minutes and restart, the temp is back at normal.

I'm ripping my hair out.