Evening everyone,
Had to replace the water header tank on my MY94 wagon a couple of weeks ago because one of the plastic outlet pipes snapped off (with aid of battery resting on it) bought a new one from Subaru, fitted it and made sure I filled it to the brim, then topped up the overflow tank to the full mark. Great I thought, all sorted, and to be fair, for about 4 days everything was ok. On the 5th day the check light came on and then went off after 3 secs, however it seems to do it about every 2 days now. Temperature never goes above the middle even sat in traffic.
I did an ecu code check and it came back with error 21 which is engine coolant sensor, so is there a special way to bleed the cooling system or is it just coincidence.........any help greatly appreciated as I'm getting worried about huge bills.


derek

 

I changed my coolant on saturday and to bleed it, i warmed the engine for 5 mins. then with a pair of gloves carefully removed radiator cap and u could hear the air coming out. Did this a couple of times and then it was fine. Make sure engine aint to hot or the water will shoot out like a ******* rocket!!!!!!

 

Did mine a while ago when I found out a certain Subaru dealer local to me had not done this on the service even though it was part of the service!

Have the car idling with the rad header tank cap off,
make sure the heater temp control in the car is on full heat,
let the engine run up to temp and keep topping up the header with your mix of coolant and warm water.
I cant remember if there are any bleed screws on the system just follow the pipework round to see.
Give the pipes a squeeze around the system and blip the throttle a bit to help shift any air locks but dont go stickin your hands in any moving parts
Once up to temp the rad fan should kick in, let this happen a few times and keep an eye on the temp gauge - check you are getting warm air through the blower in the car and top up the header and overflow.
Take car for a spin - let engine cool down and then check coolant level again once its safe to remove the cap.

 

Thanks to both of you for the info, will try in the morning......
keep you posted on progress.

derek

 

when i changed my rad i just fired it up from cold with the cap off and left it to run for an hour. Its been fine for months now.

 

Heater control to hot.

 

Thanks to everyone for the suggestions, tried removing cap after 5 mins for air to escape, still the same ,code 21. Tried rad cap off when cold and letting warm up with occasional blips of throttle, still the same code. So I parked it facing uphill outside the house (steep hill) and tried with rad cap off and a warm up, again I got the same code (21). Finally left cap on and let it warm up to normal and then let it run for an hour at tickover (very boring) fan kicked in 3 times during the hour and temp gauge stayed steady in the middle, switched off, connected black and green connectors, went through the ecu reset process then drove around until check light flashed, the cel didn't flash any codes, just a continual on/off steady flash so I thought I'd cleared the fault at last, until I got in this morning to go to work and the check light came on yet again but once it had warmed up a bit it went out and stayed out until I came back home this evening and there was my little friendly light gleaming at me again.
So I'm at a loss right now, there's obviously nothing wrong with the cooling system as it doesn't overheat at all and always get loads of hot air out of the vents. Could it be that I'm missing somethig really stupid or could it actually be a fault with the sensor when cold ?, it's in a bloody inaccessible place. If I'm standing at the front of the car leaning over, looking down between the inlet manifold and the turbo there's one on the right with 2 wires and a smaller one to it's left. Does anyone have any idea which is which?.
ANY HELP AT ALL WILL BE GREATLY APPRECIATED...........

thanks in advance

derek

 

Sounds like a dodgy coolant sensor or a wire from the sensor is nipped.