Similar to other threads on here right now my 2006 WRX is acting very odd.

Basically I had my cam belt and coolant changed by an independent last week. 1st bit of stop start driving in slow moving traffic yesterday and my temp gauge rose to just below the top before I pulled over to let the car cool down. Started her up 10 mins later, started driving and same thing happened, this time however I found a quiet stretch of road out of the traffic and noticed that as soon as I got the car on boost in 2nd and 3rd the temps very very quickly dropped back to normal again. Once dawdling along again in 2nd gear again off boost temps started to rise again.

I have checked the coolant levels (normal) and for any signs of oil/water contamination and nothing is showing up as HG failure.

What the hell could it be that is causing the hot running when off boost? I'm thinking partial blockage somewhere (heater matrix or pipework) as surely the water pump works faster/harder when the engine is boosting and would then be able to push the water past the partial blockage. Anyone think my theory is right? Or have experience of the same problem?

Also the car runs great and boosts brilliantly with no loss of performance recently whatsoever.

 

Is the fan cutting in? That's the only way the engine stays cool in stop-start traffic. Once on the move the airflow keeps the temps down. If the temp needle stops at normal and doesn't drop lower while moving the thermostat is working.

 

Hmmm I wonder if they forgot to plugs the fans back in when they put the rad back in after the cambelt change

 

sounds like fans to me

 

Wish it was the fans but they are cutting as they should when the temps rise.

 

air lock would be next thing to look at

 

I had very similar thing happening to my car, is it blowing water out of the expansion vessel?
Mine was.

Head gasket, but do check all other areas water levels, thermostat, before taking engine out,


Bez

 

It is possible to get a lot of heat into the engine running off boost. If you are at low speed and high load, there isn't a lot of air going through the radiator or engine bay thus temperatires rise. If you are on boost you are more than likely travelling pretty quickly so there is more air flow to cool things down.

 

My car was doing the same, if you cruising then it starts overheating and if i constantly on boost the temp goes down, i sorry to say that was the head gasket, the engine should not over heat at all, driving fast or slow, if its over heating then there is an issue with it, but like Bez300 said do all the checks before you take the engine out.

 

But the fans should regulate the temperature regardless, it should never get anywhere near the top of the guage. If the fans are working and the temps are still going up, there's something else wrong.

 

if your independent had maybe installed a faulty thermostat? Or air in the system I'd wager

 

Take it back to the independent & tell them to make sure they did everything right, bit of a coincidence it's playing up after having work done. Who was it?

 

Strange one...

 

I would definitely say at best it's a bad airlock, but i'm sorry to say it sounds like head gasket .

If you've got a compression tester it's not the most difficult job in the world to check compression, or get someone to do it for you.

 

Cheers for the replies fellas. Have to say the car ran 100% within normal temps before the cam belt change so I'm inclined to think something to do with this has had an effect. I will speak to them tomorrow and ask them to check for an airlock in the system and see of they'll do a compression test free of charge too. Would this definitely show a blown headgasket? The garage that did the service and cam belt change is Slow boy racing near Brands Hatch in Kent.

Surely I would see a loss in performance or other signs like a loss of coolant if the head gasket was to blame, also ive been driving the car a lot over the weekend and the temps have been bang in the middle of the gauge all the time. I did notice the coolant had the odd bubble popping to the surface when I took the cap off to check. Again, is this an indication of an airlock or blown HG?

Fingers crossed it's all ok and just an airlock.

Once again cheers for the replies. Pls keep 'em coming

 

i had my car parked for 3 years took it out a few weeks ago the car had a bad airlock bled it 3 times the car then seemed alright ,stayed off boost for 500 miles as a precaution the car ran like clockwork .i went on boost today on a moterway the car overheated ,came off boost it dropped back to where it should be when i pulled up temp was normal fans were kicking in on time im suspecting there's still a slight airlock any thoughts ?

 

Heads lifting whilst on boost HG failure.

 

Sniff test by a garage is quicker

 

You've obviously started off with a failed head gasket.... And now it's begun to repair itself!

LOL