2.5 STi Spec D....strange fault...FOUND!!
 

Hi all,


I'll keep this as short as I can.
Forged / mapped 2 years / 20k miles ago, so I think all is ok there.


My turbo (standard) is now making quite a loud spooling sound, and is dumping quite heavily - this is new to me and falls in time with :


Sitting in traffic (I have a PSi3 data monitor) the coolant temp rises fairly quickly to approx 97/98 then the fan comes in as it should.


I know this is what happens, but it's the rate it climbs that bothers me, and 2 / 3 minutes later the fan needs to kick in again.


I've cleaned out the boost control solenoid, made no difference. All hoses etc are tight, no splits. When I shake the boost control solenoid, should I hear a rattle? I can't hear anything moving in there, but not sure if I should.




Any suggestions to the rising temps? Coolant is behaving in the tank by the rad, and no bubbles....


No fault codes, nothing. Just doesn't run as well as it used to.
Heats up going uphill too. I can't help but think it's turbo related as I now hear the spooling and dump valve (standard BOV) I never used to. Plus using more fuel, wonder if my ECU is compensating for something?

If you can hear the bov, could a pipe be split somewhere?

Lift the bonnet and get someone to rev it.
should be able to hear if something is sucking in somewhere.

I've looked really closely at all the pipes, but no splits....the joys of fly by wire!


Might spray some soapy water around. Hmm, I wonder if hot air is being sucked in somewhere. Had the cold feed and airbox off earlier, that's all ok.

Were the head gaskets and head bolts uprated when it was "forged"?

Yep. Cosworth HG's and ARP studs.

I know it's an obvious one to check but oil and coolant levels ok?

Yes all good.

Its fairly unusual, especially on newage, but the re-circulation valves can fail (higher boost levels may not help).

Ps. Any smoke?

No smoke, I've never heard my BOV valve before, nor spooling.

Cracked block around the top of the liner perhaps

Could be, but then I'd be getting gasses in the coolant causing bubbles surely?

sounds like a split intake pipe to me, hence hearing the turbo and recirc valve more. Stock pipe split where it meets the turbo on my blob and I had the same symptoms

Quite possibly, I did find a small tear at that point, but covered it with the smooth part of the jubilee clip....one to keep an eye on thank you.

Well after a simple smoke test using a latex glove and a cigarette...I hope I have found the issue, which also explains the car seemingly taking in hot air whilst stationary. Up-pipe heat being sucked straight into the cold side of the turbo....yeah fab! Not.


Took off the bend section just after the airbox, put a latex glove on the open end of the inlet, and a drinking straw through one of the fingers and taped it up.


Got my fags out, blew smoke through the straw into the cold air intake....and hey presto, smoke bellowing out where the rubber end meets the turbo with the jubilee clip.


Tried to tighten etc, but the inlet pipe is pretty much toast, I can see a split.


So, do I go for standard (which has lasted 10 years to be fair) which would need the inlet manifold off I reckon, or Mishimoto or Perrin equivalent which would just need a ton of wiggling and stress? Standard air box / pipework etc.


Any suggestions?

Great stuff and improvisation.

Samco or similar mate

It's looking like I'll be going for either a black or red Samco inlet hose. I have a Bob Rawle map on the car, do these hoses need mapping in? Will my map need a tweak?


Black or red peeps???? :wonder:

No mapping in needed mate and do the colour that goes with you colour scheme

Cool.
That's the thing, I don't really have a colour scheme as such, black standard hoses everywhere, but red inlet manifold....
Maybe black to go with the stealth of a fully forged / mapped Spec D lol

Glad you found it, I was just about to suggest this and read to the bottom of your thread to see you'd found it! Well done!


As said, won't need mapping for just changing this pipe. I've used Samco hoses for years, they are very good.

Where are you buying them from and pics of when its done lol

Len at Subaru 4You has been given the task, he will supply and fit.
Will put pics up yes once done.


Not quite sure when yet, as he's busy at the moment, and I'm in no rush as have a 50 mpg Passat TDI to use anyway.
Looking forward to getting it done though and have it running properly again.


I can imagine there are many standard inlet hoses out there that are letting owners down.


I just hope this is the cause of fairly rapidly rising coolant temps whilst stationary. My theory is hot un-metered air getting sucked in from up-pipe and ambient engine bay causing lean conditions too perhaps. Not a nice recipe to have on the menu.


The coolant temp needle doesn't move up from just over the 1/4 mark, it's my PSi 3 where I'm taking my readings from, and I do trust it.


I suspect there are loads out there causing this where the owner doesn't have gauges or a PSi 3 to give them accurate live readings etc.


Fingers crossed it solves it, if not, well...one to tick off the list!
Pics to follow.

Thank you BrownPants, I just hope this is the cause. It's one of those awkward running problems that doesn't kick off a CEL....well not yet anyway.

Might be worth getting a monitor to watch things for a while. For a minimal outlay of a simple KKL cable, USB OTG adaptor and BTSSM android app you can read all the ECU parameters while running and do some data logging.

Just did the same smoke test again, but to be honest I realise now that the leak is very small. No P codes or anything, no CEL.


I'm wondering if the leak I found is far too small to cause lean conditions, un-metered air etc. This could be something internal going on I think now.


Reason being, in the lower gears, the coolant temps go down sometimes on higher RPM, or the temps can go up being RPM related.


Coolant and thermostat changed a few weeks ago. I doubt an air lock as this problem was going on before that.


I wonder if something is cracked somewhere, somewhere where it's not causing bubbles in the coolant. Any ideas?

Water pump?
not moving water as it should.

A small leak will still pull in a lot of air when you drive the car.

Possibility of water pump, but do they ever fail?
I realise that if smoke is coming out, then air will be getting in....but no lean code?


I kinda feel like getting rid of the car now, but there is no way I would sell it with any issues, I couldn't do that to anyone.


I do have a small air intake leak yes, but I think that is "A" problem, not "The" problem....time will tell.


I had it idling (drive by wire) and nobody to rev it for me, but on idle I put smoke around the jubilee clip area and it didn't appear to get sucked in.


Maybe under load it does, the hose could be half collapsing for all I know...