A snippet from the manufacturer

http://www.honestjohn.co.uk/news/leg...litre-engines/

"From a statistical viewpoint, to date 1,044 Subaru Impreza WRX STI 08/09 model year vehicles have been supplied into the UK market through our distribution network and only a small percentage of those have suffered any kind of engine failure. It was recognised very early that a modification to the fuel cut off parameters at maximum engine revolutions was required to reduce impact stresses to the piston land area, therefore an ECU map re-write was introduced on all production vehicles. Also vehicles held in UK stock were modified and a Service Campaign was issued to the UK Subaru network for vehicles already placed in the market.

From the information gathered through Fuji Heavy Industries' Engineering Teams, our Regional Service Managers and warranty information, it has been determined that engine failures have occurred due to one, or a combination of the following points:

Engine rev limits being constantly exceeded due to over speeding
Vehicles being un-officially modified outside the design brief of the engine (unit is designed for around 300 BHP or 330 BHP in the case of the STI 330S, not more)
Track use (racing, time trials, rallying etc)
Incorrect maintenance procedures, causing engines to be run with insufficient or contaminated lubricating oils
Use of incorrect fuel grade (RON)
Unofficial "grey" Imports of undetermined specification, ie. not supplied by Subaru (UK)

As previously stated, our engines are designed to be operated within the design brief. Where owners have decided to unilaterally modify their vehicles, it can be expected that failures will almost certainly occur.

The view taken by our warranty staff has been to investigate thoroughly each case presented, and where evidence is in any way inconclusive, we have always covered those units under the terms of the new vehicle warranty. As customers should rightly expect, the engine will rev freely throughout its complete range, without fault, as long as the points above are observed.

You may be aware of a recent joint venture between Subaru (UK) and Cosworth in the development of the Impreza CS400 producing 400 BHP and 375 ft/lbs of torque. This engine has been entirely re-configured from the bottom up to ensure reliability at these power and torque outputs. The high degree of testing and engineering expertise employed by both Subaru (UK) and Cosworth on this project serves to highlight our belief that simply adding performance componentry without an exhaustive development programme will undoubtedly compromise reliability - as other performance tuners have found to their cost.

To benchmark the project, a standard WRX STI engine unit was run on a Dynamometer for 50 hours non-stop at varying power and speed settings to replicate the most extreme usage and to highlight any areas of concern; needless to say, no problems became evident despite being operated under these intense conditions. Cosworth Technical Director, Bruce Wood, confirmed the WRX STI OE specification unit passed Coworth's test regime.

"We were encouraged that the standard STI engine passed our 50 hour continuous test, which we consider to be rigorous, as this indicated that the starting point for the CS400 programme was suitably robust."

Our views are shared by the international motor service community and to present an independent engineering statement from an internationally recognised motor service organisation, MSI Motor Service International GmbH (www.ms-motor-service.com) which clearly states the following regarding piston failure:

"Material faults are not the reason for ring land fractures, even though they are often the suspected cause. This type of fracture always results from overstressing the material." (Piston Damages - Recognising and Rectifying, section 3.4.4)

Our stance is clear and consistent on these issues; where customers are prepared to modify and/or operate their vehicles outside the design parameters, this will invalidate our warranty agreement because it can be expected that failures will occur through no fault of Fuji Heavy Industries or Subaru (UK) in regard to faulty manufacture or improper design, always remembering that the 08/09 STI is designed to be completely reliable at around 300 BHP (and 330 BHP for the STI 330S) but not at 350, 380 or even 400 BHP - power levels at which some owners claim to be running their vehicles. Where any doubt exists, the warranty available through Subaru (UK) is there to support any engine and vehicle defect reported.

Should any customer/owner require assistance with engine or indeed any vehicle related issue, the initial approach would be to discuss the problem with your selling/servicing dealer who will involve the services of Subaru (UK) if required. Customer satisfaction is at the heart of everything we do and it is absolutely not in Subaru (UK)'s interest, either financially or reputationally, to decline fair and proper warranty claims. We will not do it.

Delivery of excellent customer support is our goal, and our award-winning performance in this area over a period of more than 30 years is no coincidence.

We would like to thank you for choosing Subaru and ensure you of our endeavour to make your ownership experience a good one.

Subaru (UK)

8 October 2010"

Seems pretty ok to me...Found it funny that this statement from Subaru was a response to comments started on social networking...trust Facebook...giving idiots a voice since 2004

 

I think your missing the point regards the 2.5.. It's not the block.. Or the pistons.. Or the HG.. It's when all these parts are fitted together.. The engine as a whole has a lot of problems.. And it would appear to be ALL 2.5s not just the STI.. As a STANDARD OEM engine it's pretty bad.. As a modified engine it's pretty good.

 

Like Subaru are going to put their hands up and say" Yep, you got us......the 2.5 has issues with headgaskets and pistons so anyone affected by the those issues contact your nearest dealer first thing Monday morning and they will sort you out "

You need to dig a little further and you will see how deep it runs, including lawsuits against them instead spouting off on a subject its obvious you know nothing about apart from a google search.

 

I know plenty ********* want to blame someone for the result of bouncing off rev limiter at Southend on a Friday night.

 

I don't see that they need to hold up their hands...Joe Public gives it Johnny Big *****...bouncing off the rev limiter and spanking his motor and it breaks so it must be Subarus fault LOL

 

Being the expert you are can you spot the line in the copy'n'paste article you posted that proves the person who wrote doesn't know what he's talking about?

 

Well unlike a few people who mullered their motors...I'm no expert in anything mate and never claim to be. Just know what I know...Joe Public obviously knows more than the people who build the car....and isn't going to admit to driving like a bellend. Mechanics love people who know little and spend much and a lot of people on here who want to argue, cherry pick bits from a post that suits their position and then ignore everything else. I'm over it...laters peeps. Sorry if some people blew their cars up...mine are fine

 

So you are claiming that the only reason the 2.5 engine has had so many failures is because the owners have all driven them too hard ????

 

STI Pro Drive Edition. You are very much looking as if you have just arrived on planet Subaru and have yet to grasp some of the issues that have been around for many a year. Bit more homework needed me thinks.

 

The comment from the manufacturer about using Imprezas for "Track use (racing, time trials, rallying etc)" surprised me. Surely a lot of people chose a 300 bhp cooking version of a family car for the performance it can offer and the option of putting it through its paces in a safe track environment.

I can't imagine BMW advising against tracking an M3 or Porsche warning you not to take your 911 GT3 on track. Of course they wouldn't pay to repair cars damaged from known track use, but they wouldn't advise against doing it.

 

This could be the resurrection of aRSe_Matt!
Can't wait until we get on to the fuel efficient ARBs

 

I take it you have read the 56 page sticky thread about the 2.5 engine failures.?

 

I think what people simply don't get about the EJ25 is that its a 2.0 sized engine black bored-out to its limits. There's a little more to it, but in essence that's what it is. Put simple the block and heads doesn't have enough metal between each combustion chamber and the adjacent coolant passages. This engine started life out as a non-turbo engine. It was OK under than kind of load and use. But as soon as they started turbocharging it, its physical limits of this design become apparent.

Its not a manufacturing defect, or fault. Its simply because the block and bore spacing means this design is much more intolerable to faults. They have changed the casting methods a few times, used different mix of alloys, deck and webbing to improve rigidity, but its not enough. They could still do more...better composite gasket materials, head studs instead of bolts etc.

And the other factor....age. Obviously the lumps have all been endurance tested during the prototype stages, but now these engines are getting older and older, so there is more scope for them to go wrong from the way the car is used and treated: Like people negating various service items. For example coolant changes or bodged coolant changes or using the wrong coolant. So we have airlock, corroded cooling systems, in an aging, worn engine that usually is expected to see fairly hard use in comparison to its non-turbo counterpart.

The coolant issue is something of a ticking bomb in the motor industry...most motor-factors sell universal coolants, usually of two types. Very few manufacturers plainly state what their coolants contain, even fewer set their own standards. And herein lies the problem...nobody will guarantee the mix-ability of these coolants long-term. Its long term compatibility with various alloys and metals, types of rubber, neoprene, nitrile, viton, plastics. Over a few years its probably fine, but mixed with some other brand, and left in a bit longer than it should have and then doing it over a ten year period...whats going to happen? We don't know. All I can go on is experience: My Honda-engined Rover shed blew its gasket from corrosion on the gasket and head/deck faces - the antifreeze degraded and turned corrosive, I put that down to neglect. Or was it due to using non-Honda coolant which contained borates?

But another situation I personally experienced is weirder: I used to own two M54 engined BMWs, same age, I'm still in contact with both cars as they were sold within the family and both have had coolant changes over the years with non-BMW coolant. One has pretty much its original cooling system bar the thermostat and water pump, which was my fault as I damaged the pump bearing when removing the fan. The other BMW was all original, bar coolant changes and the usual thermostat (its common for them to stick open).

The problem here is our gaffer went through a phase of changing brands of coolants. The timing during this resulted in the one BMW having various brands of coolant being used, more than the other. Now it could be coincidence, but the radiator cracked...s**t happens I initially guessed - it didn't overheat, I just was greeted with a puddle and low coolant level warning on the dash. Upon replacing it the hose fittings on the old radiator just fell apart, I then broke the header tank too. It appears the all of the plastic in the cooling system had gone brittle, applying any force to anything plastic and it just fell apart! I can't explain why one BMW M54 is fine and the other had its cooling system crumble into pieces! Other than concluding that at some point it was used with a coolant that attacked the plastic.

Also the Jag went through a phase where all of the hoses went soft and swollen, along with a sludgy goop forming on the header tank caps. Why after 20 odd years it decided to do this now I don't know....other than its had all sorts of brands of antifreeze used in it and its a recent thing, so whatever I used in it at some recent point, it didn't like. I've always used 2yr or 3yr coolant in it.

I never gave antifreeze much thought until it happened. Except for OAT and non-OAT, it appears there's more to it than that. Colour means f**k all, that I do know, and there is no off-the-shelf coolant that is Subaru approved other than Subaru's own (much like BMW's, or Honda's own coolants).

I wonder if EJ25 and indeed EJ20 HG failures are attributed to this, either via corrosion or premature degradation of a component that causes a leak or air to be drawn in? Certainly could be the case on the older cars that are 10+years old. The hatches are too new to suffer from this IMO, but the hawks are at the right age for it.

The only way I guess is a poll to see if any owners out there use Subaru branded coolant changed at the correct intervals and if they suffered any cooling system or head gasket problems.......

 

Very well put. When a point is put in an articulate manner it's far easier to digest than the blunt "all 2.5 engines are c#ap cos my mate had one and it blew up so they are all c#ap" kind of statements. I get where your coming from...and I've always thought that the semi closed deck is quite a lot less than half of the closure that one sees on the old fully closed deck blocks...I mean as far as I have ever seen it amounts to little more than a little 1 inch bit of ally anchoring each cylinder wall to the outside of the block compared to the solid block of ally with very small waterways of the cdb. Bore size is a significant increase too from around 90mm to 100...so I take on board your views regarding the limits of the physical size of that casting.

I totally concur about how lax we can all be regarding our servicing consumables...I'm guilty of that myself but hadn't considered the potential detrimental effects of using non approved coolant etc...food for thought definitely and along the same lines I was thinking of how many of the problems can be attributed to human input or lack thereof.

 

Mate all due respect...I couldn't give a flying one about a 56 page piece of forum ranting to be honest unless it proves that out of 1044 cars registered in 2009...something like 6 or 700 have suffered engine failure. Let's say there was 10% of the 1044 that had engine failure...out of them 104...how many were caused to vehicles that had been kept standard, serviced regularly within manufacturers guidelines and as mentioned above using specified consumables...and then out of what's left how many were being driven with a modicum of mechanical sympathy. I appreciate there has been problems but I'm always going to struggle to believe that all these problems happened on a sedate drive to the park one morning to feed the effing ducks...Just like the haters want to believe it's all Subaru's fault and they're not owning up to it...I'm always going to be aware that for every genuine case there will be one or 2 disingenuous claims.

My old 5 Gt Turbs Renault used to run wicked when I drove it as a nippy 125 brake hot hatch...but like a t#at I took it to Van Aaken who put it up to 155 horse...after that it blew the head gasket twice...2nd time definitely my fault. Now I'm not saying everyone should keep their car standard or that I don't believe there are many credible examples. I'm merely saying I don't believe that all of it is down to the engine every single time.