Well, still got this problem with the heater blowing cold - whether on air con or not, recirc or not etc.
Air moves vent to vent as per air control dial, motor/rods and white plastic cams move when dial turned ( may have been stuck but freed now! 0 but still cold.

While checking things on this, I noticed that when engine hot the hoses were hard ( I was trying to burp / bleed any air from coolant system ) and didn't seem to move water in over flow when squeezed. A minute later the hoses were much softer ( not as soft as when cold ) ... and on a whim ( being safe, I know it shouldn't be done ) I cracked the cap on the radiator head tank ... no hiss or squirt of water. Being brave I took off the cap and lo and behold, NO pressure behind the cap ... water present ... engine had been on 10+ minutes, was hot, top and bottom of rad were hot as was thermostat housing, fans came on and off as normal...

So .. why can I take off rad cap when engine at normal operating temp - hot - and not have the coolant coming out?

Is it a water pump problem, thermostat, blockage??

Any ideas welcome!

I'll try flushing heater matrix over weekend when I get some 5/8" hose, and try again to burp the system

Thanks in advance!

V

 

I'd start with the obvious, have you got the right radiator and expansion caps on as the Subaru engines are not designed for aftermarket caps which are 2 way, the Subaru OEM on es are one way valves inside. Also check the thermostat is working proper, for the sake of what it costs i'd put a new one in, that way you've started with the basics. I'd also be tempted to change the coolant so you know its got fresh coolant in, when you drain it it's possible it could be full of crap which is causing a blockage somewhere. Basically start with the easier stuff before you get to things like the water pump, radiator, heater matrix etc etc

 

Hi, thanks for the reply.
Yes, OEM radiator cap in place on rad, the expansion tank cap is OEM STi 1.3 bar. BUT did notice a few water marks around it... so may be weakening?
Coolant in overflow bottle was rusty brown, although header tank water was clear red ... not been changed for 2 years after engine work, when water pump was also changed at cam belt change. Emptied and refilled overflow tank, still clear after 2 days.
A suggestion was swap rad cap on header tank - I have one off the Misimoto radiator which I didn't use, and that seems to help ... a bit warmer air and hold pressure / splurts if opened when hot! Also did a load of "burping" system which got rid of some air.
Next steps are flush heater core, then drop coolant for fresh and fill via Turbo water hose which was suggested by a good tuner! Probably will change thermostat at the same time.

I'll see how this goes and let you know.

 

Yeh it will be interesting to see what the issue was, hopefully it's just someing minor and an easy fix, it will do no harm anyway in flushing out the old coolant and putting fresh in as you could even just have a bad air lock.

 

Swapped radiator cap, seemed OK and a bit warmer air from heater vents but on stopping from village drive( so not booted! but enough to get to full engine temps ) there was steam as the cap was letting out pressure!!! hmmm why would it do that? Over-pressure I guess, hoses were hard. Cossie head gaskets I think on forged build a few years ago ( with block insert and head studs ). When cold I need to see if I see water movement across reservoir.
, new 1.3 bar cap ...as said water pump was new 1.5-2 years ( 5k miles ) ago, so should be OK. Radiator was hot at top, warm at bottom, so likely thermostat OK but got a new Std Subaru one on the way, and some OAT 50:50 antifreeze for after the drain and flush!

Do this lot next few days when the bits arrive, or after xmas if needed!

Thanks for the help.

 

Did you fully resolve it ?

 

Hi there,

Not fully resolved yet, as been a bit lazy over xmas and in this cold weather so not changed thermostat / flushed system or refilled with proper coolant.

As above, feels a little bit warmer after a few miles / engine up to temp, ( but hot air only really from RHS centre vent under head unit ) and thermostat does seem to be working... and it's not losing water / staining reservoir now so that was likely the old STi rad cap!

Come a dry, warmish day and I'll get under the car and do the thermostat etc.
Cheers
V

 

Minor updates.....

Finally got the turbo exhaust housing fitted. The existing one was a hybrid of a td series modded to fit gt30...made by scoobyclinic way back in the day...way back in the day before Arashi started making cast one piece items!

Hybrid which has stitch welded securing ring...and alway give grief as will always crack due to heat cycles as seen here and leaking





Nice new cast one piece item all in fitted





Also got rear subframe bushes done (x4) to stop the rear end float on heavy cornering


Put a forge recirc on it that I had lying


Be interesting now to see what flow difference is between old & new housings

and then last piece of puzzle (for now) is fit the 3" hard intake pipe to replace the scabby looking 2.75" looking one - but cant do that until the map is checked tweaked for the new exhaust housing

 

What make are those rear subframe bushes?

 

Addicted to Yellow ?

 

Just the powerflex Road Series ones
https://www.powerflexsuspensionbushe...r-109752-p.asp

id assume yours will have the fancy group N rear subframe bushes.... ICP where selling a set of those for £300 recently but theyre a full on subframe out job to fit

 

you made me chuckle there

 

Mine were Grp N, but before I realized that, a garage drilled them out to force inserts in.
So eventually I will remove subframe and redo. Or buy new subframe and use Powerflex black inserts.
I was worried they were WL! Nothing to do with yellow ness!!

 

On my way to pick my hatch up from ET

 

ha no not whiteline....i know all about your love of whiteline products

i wouldnt buy the black RACE series they are far too hard for UK roads i think - had their black series front wishbone caster bushes and it was brutal, lovely on something tarmac but terrible on anything but - which isnt good for roads down your neck of the woods!

hope it all goes well for you on collection from ET

 

good ET did not touch Your engine as failure rate is huge -one a month or so
doubt anything is to hard on oem hatch suspension, its softer than newage
other story if You have bc br coilovers fitted

 

talking about fitting Powerflex Black Series bushes...

 

right im talking about anything ,metal bushes included

 

you say that but having owned both hawk & hatch sti's (from standard to modded) i can see they each have their own merits and also downfalls - and even subaru sorted out the softness issues in the facelift if you really wanted it to remain as a standard car

 

The only place I have black Powerflex currently is the rack bushes, and they're perfect for that position.

 

Also, a heads up for spec C hatch owners; they apparently have hawk tgvs, not hatch tgvs. And by coincidence possibly, the stumble has vanished

 

whats your thoughts after driving it now? Is the sport cat worth it?

 

It was a slowish wet journey back, so not really had a chance, but power delivery was great. Unfortunately, the back box is probably toast with a loose baffle

 

Started into very minor front end revision. Decided to try mirror r205 sti setup of gloss black blade on the grill

Got a standard sti grill then got Autoskins NI to wrap the blade, changed mesh to zunsport to match lower grill then put the red pinstripe on it.

Bumper has to come off to fit it due to intercooler so will have to wait till week or so till my ribs are in better shape

Think it'll give front a slightly lower look if anything

 

That will just catch on every bump!!!!

 

Now I've driven it a bit, I'd say the sports cat and/or tgv delete have been awesome mods for a twinscroll, way in excess of the 13bhp gained. Top end power has significantly increased, and surprisingly fuel economy compared with previous mods. Edit plus caik and turbo inlet pipe
Dont know if I said this already, but jdm spec C GRBs still have Hawk manifolds if you're thinking of going tgv delete.

 

To clarify a bit further the TGV assemblies on ALL** "G12" EJ207 JDM's are the same as the TGV assemblies fitted to UK Hawkeye (G11) EJ255 / 257 engines (14011AB373 / 14011AB364).
The actual manifold bodies are different.....
JDM G12 EJ207 - 14001AC070
UK Hawk (G11) EJ255 / EJ257 - 14001AB832 / 14001AB861 respectively.

(** S206 and R205 have different motor assemblies, TGV bodies the same).

 

So, thought this problem ( hot air from 1 vent, cold from ALL others! ) was nearly sorted after extensive cooling system bleeding / burping, and radiator cap change. No water lost since, and seemed to be warmer and from more vents.
Until this weekend ... was warm ( albeit on full hot temp setting ), but on idling vents all went cold!

So finally removed oil/water separator / catch can to access hoses into heater matrix ... removed both and no dripping .. ( guess the engine bay end of these heater core hoses are above all the heater core? Or core was blocked / air locked??) . Flushed through, and got a lot of orange water ( rust? ) out, ran until it became clean water out. Boxed it all up again and checked water reservoir, was fine.

Ran engine on idle, once warmed up the heater seemed to be working normally again! Few miles run, no leaks and heater seemed to be working fine!!

Didn't change thermostat ( I had bought a new one ) nor drain / flush main cooling system / radiator, likely do that later, nor use new antifreeze etc. but seems like it was a silly problem of air lock or blockage in heater core.

Let's see how it goes for a few days.

Proper coolant change will be done shortly!!

V

 

interesting was an understatement...to give an idea of how much difference the housing made...

old housing 1bar at 4800rpm
new housing 1bar at 3700rpm

 

Result!