Hey,

so I am relatively new to the Subaru world and have an issue that’s really doing my head in. My car is an 05 WRX although I get the feeling it’s had a fair bit done to the engine, annoyingly I have no history of what, other than a service history and the bits that I keep finding that aren’t wrx standard.

so the issue I’ve got is the car seems to overheat (by overheat I have seen the ect get to 108 deg c) in a very specific set of circumstances. It’s always when I pull on to my driveway which has a minuscule slope or if the road I’m turning into has slope at all the temp gauge rockets. I have idled the car to try and recreate the issue and it doesn’t do it. I have taken it out for a half hour blast with plenty of boost and it doesn’t do it….until I get home pulling onto the drive.

I have checked for bubbling in the coolant over flow tank…nothing. No milky oil, oil in coolant, loss of coolant. I have bled the system a few times now and I’m really starting to loose the will with it. I have used the block tester kit and got a negative result although I’m not convinced that’s very accurate. Also I would have thought if it was a head gasket issue then temp would go when on boost but it doesn’t.

The car has had a nissen radiator fitted, looks to be fairly new as it’s still shiny and the fins aren’t bent. Normal temps when driving normally is 96 - 100 deg c and when boosting around 90 - 95 deg c.

any body got any ideas or suggestions please and thank you. I just want to be able to drive my car without worrying about it boiling over.

 

fans connected??

 

Yeah fans connected and come on when they should.

 

The actual temp can't jump just because of a slope unless it's somehow disrupting the flow of coolant, sounds more like a sensor or wiring issue, Does it maintain normal temp idleing with the AC on? Are you sure there is enough coolant in there?

 

I was going to say the same. It wouldn’t spike immediately on a slope. Sounds like something is moving or being squashed when on a certain angle which is causing a ghost signal from sensor or wiring ?

 

Thanks for the input, I’ll go through and check the sensors and wiring to see if I can find anything obvious.

 

Presumably you have an aftermarket temp gauge, as the stock one just reads, below temp, normal temp, above temp?

 

Have you got a way to read what the temp the hoses etc are?
Also hook up and laptop and do some logging, see what the ecu is seeing.

 

So the reason I know it got to 108 is because I’ve been using an obd reader with limited data logging function. ECT is one of the logging functions and the ecu temp follows the dash gauge.

 

Forget about it it's heat soak when its stopped with no coolant circulating.
Just keep an eye on your levels.

 

So I started tearing bits down to try and find any issues. Being a new to me car also helps me get a good look round it. Found this….

 

Good job you didnt ignore it.

 

looks like someone has bodged either a crack in the cross-over pipe or more likely a damaged bolt / seal - are you using / loosing water as that isn't a great amount??
either way thats a manifold off job to sort correctly

 

Yeah next step will be get into my garage and start stripping down properly….oh the joy.. I’ve not even done 600 miles in it yet 😩.

I haven’t noticed the coolant dropping and since this heat issue I’ve been checking it religiously. I’m really hoping this is the cause of the issue but even if it’s not it’s something that needs sorting.

 

Well you said it wasn't losing any coolant etc but it must of been. At least you found something. You will find your temps go up a few degrees when you first stop the engine after a run due to heat transfer from the hot engine and the way the Subaru cooling system is designed. The coolant continues to circulate due to convection to cool the turbo. Just like early cars had no water pumps and relied on convection to circulate and cool the engine.

 

Is the block cracked there?

 

defo looks like a crack

 

No I think it’s a stringy bit of rtv….I think. I’ll double check when I go back out to it but I had a good poke about so would like to think I’d have noticed a crack.

 

Update:

so I have changed the coolant crossover o rings. Bolts weren’t stripped I guess the previous owner just couldn’t be bothered to do the job. Radiator flushed, new thermostat and fresh coolant in and burped until no air bubbles. All seemed ok but after 25 mins of driving the temperature starts to climb reaching 104 - 105 c. I’m running out of ideas……

 

fans kicks in ?

 

Yep, everything else seems alright. I’m starting to think it’s maybe head gasket related even though no other symptoms…. I can’t think what else..I really hope not but….

 

Sniff test it is then.

 

If you are not running silicone hoses what shape do the top rad hose look like when it's overheating, pulled into the drive. They can start to balloon which is another tell tale sign of headgasket

 

Surely after this long if it was a failing HG then the oil would be on the turn and oil would be disappearing ? It’s a strange gremlin !! , is there a way of fitting another temp gauge ( external ) to see if the readings are in fact correct ?

 

my car keep temps ok,when driving over 20mph nothing You can see from back box but in queue in town or motorway You can see plenty of white clouds from back box. It's like that over 2 years. Yes it takes some coolant ,not much 200ml every 120 miles.
Hopefully it will last till September.