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2007 2.5 STI Spec D - enforced rebuild!


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Thought I might as well post up a thread for my car seeing as events have forced me into spending on it!

Last December I bought a 2007 2.5 STI Spec D PPP with 50k miles from an independent dealer in Sheffield. It had a full service history and was in great condition throughout. The only thing I didn't like was the gigantic GB270 spoiler which was not my cup of tea.

I was fully aware of the potential head gasket and ringland problems that these suffer from, but I wanted the a hawkeye and I always liked the idea of the subtle Spec D so thought I'd just buy carefully.

When I found this car I checked the coolant level which was fine, checked under the oil cap, which was also fine. There was no smoke from the exhaust, no overheating etc so happy that I had found a good one, I bought it.

First thing I did, before even getting the car, was to order the original small spoiler. Everyone I know has said I should have kept the big one, but I want a standard looking Spec D, and that spoiler isn't discrete in any way.



Back to standard:


Over the next month I covered about 500 miles of mixed driving with no apparent problems. But I found myself constantly worrying about the head gasket and pistons, spoiling my fun a bit. I was checking the oil and coolant every few days when I noticed that the coolant level in the overflow tank had dropped very low. Nothing else seemed amiss so I topped up and carried on.

I checked again a few days later and once again, the coolant level had dropped. Getting very worried now, I ran the engine and watched the overflow tank and noticed some bubbles coming up in it. After a couple of minutes this stopped. I did some more reading up and managed to convince myself that it was just an airlock as there was still no over heating.

Then, a couple of days later after getting back from a drive, I left the car idling for a couple of minutes and the dash water temperature gauge suddenly shot up to the 3/4 and steam poured from under the bonnet. When I checked, I could see the coolant was right at the top of the bottle and had sprayed out over the radiator. Not good! Once it had cooled down, I could see a very light rainbow sheen on top of the coolant.

Seemed like a bad idea to drive the car again so I had it trailered to a Subaru specialist, which is where it still is 2 months later!

The car was diagnosed with early stage HGF, and on dismantling the engine, they reckon it's on cylinder two. Here are the photos, but I'll admit that I can't tell anything from that myself!








I was originally just going to get the gaskets replaced with uprated versions, but the garage said that its possible that the crank bearings could have been damaged and that it's not uncommon for people to just replace the gaskets only for the bearings to fail and ruin the engine completely a few hundred miles later. So I agreed to a bottom end rebuild with Cosworth gaskets and ACL race bearings.

This then got me thinking about the pistons and the potential ringland issues, which I didn't want to develop after shelling out for the rest of the work. My initial idea was to just get them replaced with standard pistons as I wasn't planning on going after more power. However it turns out they're not much cheaper than forged, so I've said I'll have Mahle pistons instead. And while it's all out I've decided I might as well have a new clutch and cam belt change.

So that's the sorry tale so far, which will hopefully get better over the next couple of weeks when I get the car back.

Once I've run it in, I intend to have it remapped to take advantage of the uprated parts. After all the expense of the rebuild, I'd rather not splash out on things like FMIC, exhausts etc, but if there is anything sensible that I should consider adding at this point, now is a good time to tell me! For now, I just want to get the most I can from the PPP bits along with the now hopefully safer internals. Does anyone know what sort of power would be possible with this in mind?

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  • 4 weeks later...

Happy to say that I've got my car back nearly three months after the head gasket failed.


I've done my first 100 miles on running in oil and have just had the first of three oil and filter changes.


Here are a few photos of the build...


The uprated bits:








Plus a new clutch, skimmed flywheel, inlet flaps deleted and full cambelt & pulleys change.


And some oily bits:








And a really scary bit:




So it turns out the car did my a favour by blowing a head gasket as it looks like the oil pick up pipe would have completely fractured, probably destroying the crank and block. I hadn't realised that this is yet another fairly common problem in these engines.


So hopefully I now have sorted out most of things that Subaru themselves should have done properly in the first place and can start thinking about some more power. After another 900 miles of boring running in.


Trying to decide between a sports cat or a new turbo before I get it mapped.












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WHo ever said do the crank bearings as well is absolutely bang on, Mate found out the hard way.


Was the block not skimmed before being built?


Receipt just states "heads skimmed and pressure tested & block sent away for honing".


I just let the guy get on with it to be honest. I'm assuming / hoping he knows his stuff!

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ah wondered if that was the case. Mate of mine uses him for general servicing.


I've used them before a few years back when I had a blob WRX and they were always spot on so I'm going to go with my gut feeling that it's all going to be okay. Not much else I can do really!

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Is your ppp upgrade a full exhaust to the cat. As not sure if they change it all and what size the pipe is.




Sent from my SM-J320FN using Tapatalk









I'm pretty sure it's just back box and maybe one other part. I had a feeling that one of the cats is removed as part of it, but the official blurb just says "silencers":






Not a great deal for the money when you look at it like that!

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On 13/04/2017 at 5:41 PM, coldcuppatea said:







I'm pretty sure it's just back box and maybe one other part. I had a feeling that one of the cats is removed as part of it, but the official blurb just says "silencers":









Not a great deal for the money when you look at it like that!

Benefit was is pumped up the performance a bit but kept the warrenty intact. Given its a 2.5 not a bad thing hahaha

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What size pipes does the exhaust have . Subaru and prodrive don't keep any records. Not 3inch as too quite. I wonder what air filter they used..


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