jc_1989

Hi all, first time posting, so be nice!
I bought my first scooby in march, after wanting one since I was little. It’s 2006 Hawkeye Wrx thats engine has been rebuilt to STI spec, lots of work has been done, and it’s running 381bhp. I love it!

Long story short, I tested the coolant after I got home with it and was checking it over, and found it needed changing. So I drained it down, flushed it through and replaced it with genuine Subaru coolant. I tested the thermostat whilst I had it apart.
Since then I have had the temperature gauge rising to 3/4 high, so I’ve bled/burped the system twice. It’s now only doing it on boost under heavy acceleration, then if I drive normally the temp drops to normal after 5 minutes.
is this just a case of bleeding/burping the system again? Or do I need to look elsewhere?
P.S - the heaters blow hot and the fans cut in as they should, I drove it home from Heathrow when I bought it with no issues and have been stuck in traffic with no issues, it’s only since I changed the coolant!


hope that all makes sense! TIA!!

Vxr2010

Are the two caps back on the correct places , the sprung one on the pressured expansion tank on top of the engine , and the non sprung one on the radiator , has it been bled properly , i find facing up hill , expansion tank pressured cap off , start car , top up a little at a time into the pressured expansion tank , until it bubbles no more then fully top up

jc_1989

both caps look original and are both sprung, the look exactly the same.
I’ve got a bleeding kit with a funnel that allows it to hold fluid whilst the air bubbles out with it running.
mill try bleeding it again on an incline and see if that helps

Vxr2010

The pressured expansion tank cap is sprung , the rad one is not and does not have the two tabs on it like the pressured cap , i don’t know if the caps are your issue but you do need a new rad cap , the sprung caps can fail , not visibly obvious when they fail , try swapping the caps over and buy a new rad cap 👍

Vxr2010

Import car parts are a good option for parts , but check the photo differences between the caps

JdmSti2006

If a car was ok before coolant change doubt it will be cap issue.
Strange as almost all 2.5l have an issue when changing coolant ,than people drive them finding it needs another rebuild.

Dan.jo

Did you drive it enough before doing the coolant change to confirm the overheating issue wasn't already there? Is it pushing coolant out the expansion tank at all, or does that stay at the same level when hot regardless of how it’s driven?

Vxr2010

I was hoping to try and resolve the little things first ie caps , if the pressured expansion tank cap is not working it could be the cause of the issue , a lack of sealing and no pressure then over heating , or too much sealing going on , or just not been bled properly , Other HG signs are air in the pressured expansion tank after a drive and full cool down , as the engine is running a constant stream of bubbles coming out of the non pressured expansion tank ( the one that bolts to the rad ) , the coolant in the non pressured expansion tank not returning to the engine , but until you know you have bled it properly then it will be showing both those issues any way , swap caps buy new rad cap , bleed system fingers crossed , 👍

Croney

How did you refill it, search on hear an old thread by alcazar. Basically remove all caps, remove the turbo coolant return pipe, put a funnel into the coolant return pipe coming from turbo, and very very slowly fill it, don't let it glug, rad cap on when it's upto that level, then keep filling till full, start car running up to temp topping up as needed, blipping the revs also help, but you can not burp this engine in the normal method, I don't know why but if you get get an air lock filling it ain't coming out, slow filling is key

albob

The Alcazar method - post 11
https://www.scoobynet.com/scoobynet-...-air-lock.html

jc_1989

thanks guys, bled for a third time in the hope it was sorted, but still temp rises to 3/4 gauge on boost, settles down again on normal driving.
didn’t have the issue before, drove a lot and hard at times with no issues, will try a new rad cap tomorrow, if not then will drain and refill starting from the beginning!

JdmSti2006

3/4 temp gauge?
mine is way below half, I panic when is going over 1/4 line as it fumes white smoke when stationary
approx 4 weeks left till rebuild starts

jc_1989

yeah mine usually sits 1/4 way, kicking myself for touching it to be honest but thought I was doing the right thing! 😂

Vxr2010

There is nothing to say you broke it , if it is HG i expect it was there before you bought it but did not rear it’s head , my first 2.5 fail was after a track day , i was hitting 160 plus quite a few times and think before the day it was starting to let go so it was not a big surprise, the over heating was on off for a 100 or so mile drive home , appeared fine one minute for some distance then got hot again but never fully over heated to the point of not drive able , getting it repaired i then learnt go to a specialist not a normal garage , and one year later the bottom end went , but the engine had not been forged before , so on an un forged engine if hg goes then bottom end will follow soon after , if it is hg it’s not a massive job to do and as engine re builds go is not horrendously expensive , but let’s hope it’s another issue

Vxr2010

Where roughly town wise do you live ? You said on the way back from Heathrow ? If you are near I can maybe come and have a look if it helps ?

jc_1989

Sorry for the late reply, I live in Ashford Kent, where are you? Do you know the correct part number for the right radiator cap?

Vxr2010

Hi , im other way to you , sorry bit of a drive , have a look on import car parts , they are quite quick at shipping too , or just give them a call and do it all over the phone 👍

jc_1989

I have done thankyou. A lot cheaper than the stealer!

Vxr2010

There’s a number of non uk suppliers , partsouq , Megazip and amayama , who are a lot cheaper but add around 20 to 30 per cent for import costs , but it often still works out better , the last one i mentioned can be good on prices and seems to be able to source more parts 👍

ade_sti

iTrader: (2)

Hi mate - sorry to hear about your coolant problem when you have only just got the car. When you say you tested the thermostat when you had it apart - did you remove the water pump? Just wondered - Ade

ade_sti

iTrader: (2)

Just to check - does your radiator cap look like this

and expansion tank like this…

Vxr2010

Yes the rad cap has no spring on it , the pressured expansion one does have a spring , to allow coolant to flow to the rad and back

jc_1989

I didn’t remove the water pump, just the stat in boiling water. I only tested it as a matter of course, as it was fine before hand, just seemed like I might as well do it for the sake of 2 bolts

it has two matching ones on it like the lower picture, so that’s not a great start.

Thankyou for your help so far, I have a cap arriving Saturday so fingers crossed it fixes it!

jc_1989

So the new rad cap and alcazar method of bleeding didn’t work. Back to the drawing board. So annoyed right now!

JdmSti2006

im on 0.9 rad cap from wrx for about 4 years and nothing wrong with it,it keeps pressure when hot with no issues, i owe the one You bought but it does not fit on my rad.
Hopefully it's not head gasket on Yours but it looks like You toasted it when pointer hit 3/4 .
My car steams when stationery and smells badly but no movement over 1/2 even in yesterdays heat when I abused her to a 8k redline.

Vxr2010

Maybe worth putting a new stat in , and see if that helps , once it’s all back together and fully bled , start it up and let it run , there will be some bubbles in the expansion tank on the rad , the bubbles should stop after a while , if it’s still bubbling consistently then that’s a good indication the hg has gone , second indication you take it for a drive the radiator tank fills up then the level does not return back to normal when fully cold , the fully cold is quite a lot of hours to happen , you can also try a sniff test but this can sometimes be not conclusive , you need to have a stat fitted as it needs it to run properly 👍

Vxr2010

Adding to that , swap the expansion tank cap with the other expansion tank cap you had , don’t put the rad cap on it , if it’s not maintaining the pressure the coolant will over heat and bubble

jc_1989

I just can’t understand how changing the coolant can cause so many problems. The only reason for changing it was to avoid exactly what I’ve caused…. Really don’t want to have to put it into a specialist garage but feel like I’ve got no choice now.
it never overheated before I changed the coolant, not even in traffic on a hot day or a two hour journey back from Heathrow, I’ve driven it hard to work and back as well without issue.
It’s literally since I drained the coolant and refilled it. Nothing else has been done.

anyone want to buy a scooby? Lol

Vxr2010

It’s getting hot but we/you don’t know if it’s done any damage , try the stat as above , maybe you did something wrong when putting it back in , I’ve never had a bleeding issue , i just top up but not fill up , the pressured tank as the cars running , there’s often lots of bubbles , when the bubbles stop then I fill it up and put the cap on , take it for a drive then re check and top up both tanks when fully cold 👍

jc_1989

How much coolant should be in the radiator overflow when cold? It’s got an anodised aftermarket one on it with no fill lines