Overheating issue this morning

[SpeedySub]

Hey guys

On the way to work this morning I was sitting at the lights and noticed that the temp gauge was higher than normal, not into the red but up to the line before the red. I did have the heater cranked up full, when I drove between the next set of lights it went down a bit then while idling it crept up again. I turned the car off and on again it it drop then back up again.I did watch it fluctuate up and down quite quickly at one point. Once I got moving it started to drop and by the time I got to work it seemed ok. Any ideas on whats happening, Could it be air trapped in the system? The water level seems fine, hoping not head gasket related!

P.S

It has a new thermostat and radiator (well about 10 months old)

[megamac]

Replace thermostat (again) and go from there? Process of elimination yo

[SpeedySub]

Might have to be the way to go. Was hoping that is was a xxxxx is the problem, do y and it will go away. Could it be related to the little bit of thrashing I gave it the night before.

[Rosssub]

The bit of a thrashing the night before might of pumped an air pocket out maybe, keep a good eye on temps and fluid levels. Stick it into test mode and make sure both radiator fans are working ok too.

[SpeedySub]

 Rosssub said:

The bit of a thrashing the night before might of pumped an air pocket out maybe, keep a good eye on temps and fluid levels. Stick it into test mode and make sure both radiator fans are working ok too.

Actually that reminded me, I was going to post on here about how to find out if fans were working, as Im not sure that I have heard them come on lately. Test mode is with the black and green connectors under the dash right? I take it when you plug them in it cycles through everything like turning fans on and off

[Rosssub]

Yip, just the 2 green plugs under the dash ignition on/engine off. Just above the clutch pedal, or where the clutch pedal should be. The fans will start cycling on/off and all solenoids will pulse:

[SpeedySub]

On the drive home it spiked quickly a few times but usually dropped just as quick. when pulling up to park when picking son up from training it spiked really quickly to just below red. i didnt hear the fans going when i popped the bonnet. after 20 minutes off it was fine for the last 5 kms. got home and tested it using the green plugs i heard the fans going. each seperatly and both togetherso the fans work but dont seem to go on during driving

[Rosssub]

Odd. If you get it up to temp, leave it idling and get someone to watch the temp gauge. Pop the bonnet and watch the passenger side fan, it should kick in briefly after 5-7 minutes of idling.

If the temp rises and the radiator fan doesn't kick in at all (giving they work in test mode), I'd suspect a dodgy coolant temp sensor.

[SpeedySub]

Ok so trip in this morning absolutely no issues. Temp gauge didn't move past its normal position. After having a read on line last night I tried the A/C first thing this morning and fan came on for that, so guessing it could be a faulty sensor. So will look at replacing that as it can't hurt either way. I will have a look around today for a sensor. Anyone know of any good places to pick one up in Christchurch? can get one off Ebay (didn't find any on trademe) but the cost of shipping seems really high.

[RAYDEO]

i was going to suggest a faulty sensor, as if the sensor was running dry (air lock or bubbles) it would drop not rise, and my other thought was check the fans but you have done that already.

[SpeedySub]

 RAYDEO said:

i was going to suggest a faulty sensor, as if the sensor was running dry (air lock or bubbles) it would drop not rise, and my other thought was check the fans but you have done that already.

I did find last night that they have 2 sensors, one for the ECU/fans and one for the temp gauge, I was wondering if its a faulty temp gauge sensor. Maybe thats why it spikes so quickly? Its really confusing as I can't seem to find any other threads or forums that have had the same problem. Overheating issues yes but not the same issue with temp gauge readings. All the other ones the gauge steadily increases not a sharp spike in temp.

[SpeedySub]

Ok, so still having issues with it over heating. When it was showing at the 3/4 mark I pulled over and checked the radiator. Top hose was really hot and bottom was cold/luke warm with the radiator core cool to touch. A little research has suggested it could be a thermostat shut closed, failed water pump or even radiator cap needs renewing. The way it has been spiking (today it stayed at 3/4 for longer than normal, couldn't pull over as nowhere to stop but it then suddenly dropped to normal) I am thinking the thermostat is sticking closed then popping open. SO I think I will replace it this weekend. Anyone one agree or disagree with the diagnosis? (still not sure about why fans not coming on though)

[RAYDEO]

i would agree.

[SpeedySub]

 RAYDEO said:

i would agree.

With Thermostat?

[RAYDEO]

Yup. That's my pick.

what brand one the one you put in?

[SpeedySub]

The last thermostat that was put in was done at the place I brought it off. Crowesport in Christchurch, they are a subaru dealer ship and repairer. I did have an overheating issue just after I brought it about a year ago. It over heated on the way back from Kaikora so took it back and they replace thermostat and radiator. No real issues since then (till now). So I am assuming the put a OEM thermostat in.

[RAYDEO]

take it back to them, they have the history, and they are usually pretty good...

[SpeedySub]

 RAYDEO said:

take it back to them, they have the history, and they are usually pretty good...

Will give them a call today. I take it the thermostat should last longer than this?

[RAYDEO]

Absolutely, i did mine in the weekend and that was seized open, that would have been the factory item, and its done 160,000km

[SpeedySub]

Will let you know how this goes.

[millenniumfalcon]

will be interested to see what you come up with, I seem to be experiencing the same symptoms with my be5. i have changed coolant sensor and thermostat also have just had cambelt and waterpump replaced.

[SpeedySub]

 millenniumfalcon said:

will be interested to see what you come up with, I seem to be experiencing the same symptoms with my be5. i have changed coolant sensor and thermostat also have just had cambelt and waterpump replaced.

Did you do this yourself? If so from what I have read you may have an air bubble/pocket if the system wasn't fully bled of air bubbles. (does the heater still blow hot?)

[millenniumfalcon]

I only replaced the temp sensor myself. it was bleed a few times and im pretty confident it isn't a air pocket, but that was my first thought although the heater has worked as it should the whole time, never gets cold or anything oddball. the only thing I can think it could be from what iv been told and read is could be either bad wiring (grounding out every so often) or leaky head gasket but hasn't shown any signs of head gasket so im trying to stay positive haha

[Rosssub]

Is the passengers fan working as it should? Can pull your thermostat out and test it:

Starts to open:

76.0 — 80.0°C (169 — 176°F)

Fully opens:

91°C (196°F)

If it tests fine and the fans are working as they should, it's not losing coolant or spitting more coolant into the overflow than it used too. You could try a heater core bypass to see if it has any effect.

[Jambun]

How do you test it a thermostat Ross? Stick it in boiling water?