matscooby

iTrader: (3)

Hi All,

I have a problem which in all my 3 impreza's and my 2nd year into owning this V2 STI 555 with the STI RA drivetrain, I've not had a problem like this before.

I know its been hot these last few weeks and temps will rise slightly but this problem is abit different.

Its always serviced every 3k miles with either 5w-50 Halfords trackday oil or 15w-50 oil mobil 1 motorsport oil.

Whenever I have gone for abit of a heated run and pushed it, the temp has never gone above 100c in the hot or cold weather.

Within this last week when pottering along the motorway doing 60mph at 3000rpm or wherever I'm going, the temps have risen to 115 sometimes 120c and I have no choice but to pull over and cut the engine off to let it cool down.

Water temp has not risen atouch and oil pressure stays between 4 and 6 bar.

What possible cause could there be to make this Oil temp rise to such a high figure without even pushing the car to its potential.

Oh yeah the engine is standard, well except a K&N Panel filter and a centre decat.

Any advice would be appreciated.

Matt

every1sgottablue1

Could be head gasket

matscooby

iTrader: (3)

I thought that but the water temp aint rising, YET !!!

WRX RCY

Is this the first time and only time is happened?

matscooby

iTrader: (3)

It started last week when on route to Port Talbot in the pouring rain. It even managed to get around 115c in the ****e weather.

Since then its happening daily.

Its odd because everthing else is reading fine.

I've also tested another guage thinking it could of been faulty but that also read the same temp.

WRX RCY

What about the sender? Perhaps thats faulty

matscooby

iTrader: (3)

Yeah, it could be.

I'll have to get one quite pronto before the run to the POD.

I might put it into the garage to have the Rocker cover sorted too.

every1sgottablue1

My head gaskets have gone, and car is currently at API for a rebuild. I could drive the car normally without overheating if drove like miss daisy, but as soon as using any boost it overheated.

Stevesbluewrx

iTrader: (4)

What about Thermostat? I had higher temps etc and once I changed to a ZeroSport thermostat this resolved the problem.

They open up something like 8c earlier allow the cooling process to take effect etc.

Steve

Splitpin

Matscooby - a bit of clarification please before we go further as your OP reads a little unclearly.

Are you telling us that your oil temps are rising to 115/120 celsius, and that your coolant temperature is staying as per normal???

matscooby

iTrader: (3)

Hi Splitpin, yes.

The oil temps are rising to 115 120c but the water temp stays the same.

I would of thought that if the head gaskets were going, the water temp would also rise which would mean the thermostat wasn't doing its job properly which would then explain this problem.

Splitpin

Yeah, it's an odd one. There's no other evidence of HG failure is there? Is the coolant level staying brimmed in the header tank, or are you losing some? What year's this car, and what are you monitoring the water temp with, the stock gauge?

As you've already discussed, ruling out a dodgy oil temp sender would be very worthwhile. Thermostat probably a less likely suspect given that you say there's no upward movement on the coolant needle.

Has this engine always been run with a good quality coolant mix, and changes at the appropriate intervals, or is there crud/rust in it? Given the symptoms, the one thing I was wondering about is a blockage in the coolant supply/return to the modine, or possibly within it.

matscooby

iTrader: (3)

Odd one yes.

As for the HG failure,the passenger side head is bone dry and still looks clean as ever.

Drivers side head is slightly different, along the seal on top it does have abit of a oily crusty residue along the top rim if you know what I mean.

As for for the water, it only pumps out a tiny amount of water when giving the car abit of right foot but this is very little and yes its the stock guage I'm getting the reading from.

The coolant was changed back in Jan 2010 but it is looking slightly rusty currently.

I forgot, its a MY96 V2 STI 555 with the RA drivetrain.

WRX RCY

Does the oil temp rise when the car is stationary?

matscooby

iTrader: (3)

Nope, it does start to drop very slowly when stationery

matscooby

iTrader: (3)

I don't know if this is right or not, but I was told that if the engine is running lean and the in-cylinder temps are hotter due to it being lean, this could raise the Oil temp.

matscooby

iTrader: (3)

All sorted, it was a sensor issue thankgod.

Thankyou everyone for your input, much appreciated.