Hi, this is my umpteenth thread re this problem and everytime I ask, the fault does something a bit different!

Here we go, I think I have a temp sensor fault but read on and see if you agree. The check engine light on my 95 wrx import came on intemitantly but would go off when driving and the car warmed up, didn't see the light for 3 or 4 days at all and thought the problem had gone away. In the last day or 2 the light has been coming on more often when i then realised it was coming on when the cooling fans kicked in and went off when they did. Today the fans were on most of the time and this evening they were on permenantly. Even when the car was cold they came on approx 5 seconds after starting the car.

The car is now a bit difficult to start and seems to have a bit of a flat spot on pickup. After a 6 mile run (fans on constantly) I immediately felt the top hose on the radiator which was warm (approx 30 deg's) the bottom radiator hose was stone cold, I take it that this is not normal?

Could there be a faulty temp sensor which is making the ECU think the car is running to hot and therfore running weak? If so where is the temp sensor, i've had a good lok and cannot find it.

Oh yead, i've had the battery checked which shows it is unservicable and reading 38% and 52% capacity on two seperate readings/machines. The alternator is providing 13.8V to the battery. Take it I need a new one?

It's going back to the garage soon but wanted some impartial advice beforehand, cheers (really sorry bout the long thread but could do with some advice)

Paul

 

You seem to have an airlock hence the differences in temp of the hoses.
The temp sensor is in the block by cylinder number 3 (nearest the turbo) and is orangey/brown.
I would sort out the airlock first.

 

If it was an airlock would it not be the bottom rad hose that was warm and the upper hose cold? Presuming its like a radiator in your house? Could that be the cause of the problem or cold it be the sensor also? cheers, again!

Anymore suggestions would be much appreciated

 

No.

Normally, an airlock on the EJ engine results in:-

1) Top hose still hot - and normally more hard i.e. under greater pressure than normal
2) Bottom hose stone cold
3) No hot air out of heater when temp and fans are at max.

 

Thats me told, ha ha. How do you get rid of the airlock? I haven't a scooby doo! Re point 3 above - the in car heater works just fine. Does it sound like the temp sensor anyhow?

Will it cause any problems using the car in this state? I have looked under the dash for the fault finding plugs but can only find a black plug with just one wire either side?

Its driving me mad, ggrrrr! Anymore suggestions?

 

Plugs may be taped up and therefore an **** to find and yes get rid of the airlock before using the car and yes will most probably be a temp sensor fault either the sensor or sensor wiring perhaps.

 

Cheers myblackwrx, but how do you remove the airlock, i've googled it but can't find anything about the scoob, really don't wanna **** things up! If you can tell me how please don't be affraid of s-p-e-l-l-i-n-g it out as i'm not great with this sort of thing!

Cheers mate

 

1) Undo bottom hose and run the coolant out into a suitable bowl. Reconnect hose when all coolant is totally drained.

2) Disconnect the small hose that joins header tank to rad (it's the slightly fatter one of the two small narrow ones). If disconnecting at the rad end, be careful not to break off the plastic nippple moulded into the end tank.

3) Disconnect the large hose that goes to the middle of the header tank (this is the turbo coolant hose)

4) Remove pressure cap on header tank.

5) Wedge a sutable sized funnel in the disconnected turbo coolant hose and very gradually refill with the correct 50/50 mix of water/coolant. This should take a while - but don't rush (the funnel will not allow you to rush anyway).

6) When you see coolant run out of the rad's end tank bleed nipple then continue topping up until the level in the header tank is just below the pressure cap's mounting neck.Put cap back on.

7) Reconnect the turbo coolant hose back onto the centre of the header tank.

8) Reconnect the narrow coolant hose back onto the rad's end tank nipple.

9) Coolant is now reinstated - hopefully, without any airlocks.

10) Put heater to cold and run engine to temp - make sure rad fans kick in after a few minutes after getting up to normal temp.

11) Turn heater to hot and fan on - is there lots of hot air coming out?

12) If everthing is okay, make sure temp needle doesn't rise but remains in the middle.

13) Take for a test drive, checking temp doesn't rise.

14) Return home, park up and recheck level when engine becomes cold after about two hours standing - top up header tank as necessary.

 

Your a star mate, it seems to have all the symptoms of an airlock but the heater blows really warm air out and the temp gauge doesn't go past half way, like i say the fans kick in straight away, even when the car is cold!?

Can the coolant temp sensor slowly deteriorate or do they just die?

 

Mine deteriorated.

 

Sounds like the coolant temp sensor if the fan's are cutting in from cold (fail safe mode) and you should have Code 21 stored in the ecu.

Brown Sensor on the coolant cross over pipe for the ecu, smaller sensor for the temp gauge :





Mick

 

still trying to work out what part of the engine that is, lol! thanks for the replies from everyone so far, gonna get my scruffs on tomoz n get under the car n have a good look around! let u know how it goes! any more suggestions welcome! paul

 

Paul - the temp sensor is underneath the inlet manifold at the back nr the turbo... it hard to see under all the hoses etc but it is there...

Sounds like our problems are the same - but mine is worsened by no CEL light!

 

Better "location" pic :






Mick

 

Cheers for all the replies, have been taking to a good friend who used to be a m/bike mechanic, he thinks that the botom hose may be cold as the fans are cutting in too early, obviously due to the temp sensor, and preventing the engine/rad warming up, is this possible or is a cold botom hose a definate sign of an airlock, sorry to be a pain but enjoy learning new techy things! :-)

 

the fans would not be able to keep these engines cold, i would look at new temp sensor and thermostat and then use the instructions above to refill and remove air lock

 

Another question for you guys, when the system is flushed and re-filled what is the best coolant to use, i've heard that you should only use genuine subaru coolant, is this correct? If so is there a reason for this? Is it different on imports? cheers ears!

 

sorry to barge in but i fitted a new all alloy radiator a couple of weeks ago and i've noticed the offside of the rad is hot and the nearside is bearly warm,the temp gauge needle is in the middle as normal,i have hot air,does this sound like an air lock symtem,i filled it slowly let it run for about 30mins

 

Did you re-fill as the guide above suggests?

 

sorry to barge in,i fitted an all alloy rad a couple of weeks ago now i have hot air from the heater,the offside of the rad is red hot and the nearside is just getting warm,i filled it slowly ran it for about 30mins(the fans did'nt cut in)does this sound like an air lock?

cheers

 

err......dissappearing reply.....doh

i did'nt do it that way,only just read that way of filling it up,is that a better way of filling it?