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Engine Rebuild


Stevieb08
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Head gasket issues have started happening on my 2006 Impreza STI Spec D so going to rebuild it.

Planning to do it at home taking the engine out and replacing the gaskets and studs with ARP ones. Thinking of using the cosworth gaskets but dont know the OEM thickness as there's three options, 0.78mm, 1.1mm and 1.5mm.

Also any other recommendations to change out parts while the engine is out? Already have the clutch on the list.

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21 hours ago, Stevieb08 said:

Head gasket issues have started happening on my 2006 Impreza STI Spec D so going to rebuild it.

Planning to do it at home taking the engine out and replacing the gaskets and studs with ARP ones. Thinking of using the cosworth gaskets but dont know the OEM thickness as there's three options, 0.78mm, 1.1mm and 1.5mm.

Also any other recommendations to change out parts while the engine is out? Already have the clutch on the list.

There's a general consensus on this forum that if you have a knackered head gasket you also need to renew all the bearings in the bottom end as they would have sustained some sort of beasting due to water ingression in the combustion chamber and maybe some sort of hydraulic locking/extra cylinder pressure, first I heard of it tbh was on this forum but they seem to be adamant about it, no idea where the info originated, can only assume was from tried and tested engine builders relaying the info to members having head work done 

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As above, if the headgasket on a 2.5 goes you want to be doing the bottom end 100%. Friend of mine went to a well known tuner who disagreed with that and less than 1000 miles after it dropped the bottom end.

Personally i'd look at getting it closed decked while its out (i had the 2.5 in mine closed decked), its around £500 (speak to Alyn at AS Performance) so not bank breaking in the grand scheme of an engine but well worth doing. Also means 500bhp is a realistic reliable target if you ever want to got hat far.

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1 hour ago, coldcuppatea said:

 

I'd first read that on here and was going to ignore it until the garage that were doing my head gasket said pretty much the same thing.

 

Might as well put forged pistons in at the same time.

 

Purely out of noseyness what garage is it at?

 

As far as forged piston i would say its a must, headgaskets and ringlands are a big failure point on a 2.5 so you don't want to have it rebuilt and find it breaks again and your back to square 1 needing another build.

 

Subaru changed the pistons from proper forged to heat treated cast and there pretty crap by comparison.

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Just now, coldcuppatea said:

 

 

2500 miles since the rebuild now. The big test was a trackday last Sunday, which it survived!

 

Got to say Martin has been spot on with it all.

 

 

 

Sent from my iPhone using Tapatalk

Cool glad its sorted. such ashame subaru made such a monkeys job of the engine in the first place

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On 29/06/2017 at 1:11 PM, Tidgy said:

As above, if the headgasket on a 2.5 goes you want to be doing the bottom end 100%. Friend of mine went to a well known tuner who disagreed with that and less than 1000 miles after it dropped the bottom end.

Personally i'd look at getting it closed decked while its out (i had the 2.5 in mine closed decked), its around £500 (speak to Alyn at AS Performance) so not bank breaking in the grand scheme of an engine but well worth doing. Also means 500bhp is a realistic reliable target if you ever want to got hat far.

Can vouch for Alyn, met up with him the other week, knows his stuff really well. Good guy and not in it to rip people off either. Said it was well worth doing the closed deck for reilability as well.

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  • 1 month later...
Just now, Stevieb08 said:

 

So I have this list together, the A/C pump and CV joint aren't for the actual engine obviously.

Anything I've missed? Not doing the forged pistons unless they have visible issues.

 

Capture.JPG

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1 hour ago, Stevieb08 said:

 

So I have this list together, the A/C pump and CV joint aren't for the actual engine obviously.

Anything I've missed? Not doing the forged pistons unless they have visible issues.

My advice, do the pistons. There well known to be a failure point (ring lands) and you don't want to rebuild it to then have to rebuild it again replacing everything again.

 

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I would do the pistons as well personally. May as well while you're doing everything else...

I priced mine up the other night...£8.5k 😬 Haha @Tidgy or @savage bulldogs may be able to help consolidate my list though as I probably have ridiculously unnecessary components for the target is aiming for...(looking around 500hp...priced 14mm studs, new cams etc. Of course everything new and from RCM which is pricier than some other brands like ARP which I'd probably use)

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Price depends on what spec you go for. Best advice if your aiming for a target find a tuner your happy with, speak to them about options and targets and go with that. Wrong spec and mismatching parts could mean a total dog of a car.

 

I would stay clear of rcm parts, expensive for what they are and not always as good as you think.

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I'd eco tidgy when it comes to forged pistons for the sake of £450.

 

You'll need a few more gaskets like headers,up pipe, turbo outlet ,water crossover and dipstick o rings , front and rear crank seals ect .

 

Filter, fluids and timing pulley/tensioner water pump ect ?

 

Consider replacing the clutch and spigot bearing , if it's due soon or your turning the wick up .

 

As it's a lot eaiser while the engines out . [emoji6]

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6 hours ago, Tidgy said:

Price depends on what spec you go for. Best advice if your aiming for a target find a tuner your happy with, speak to them about options and targets and go with that. Wrong spec and mismatching parts could mean a total dog of a car.

 

I would stay clear of rcm parts, expensive for what they are and not always as good as you think.

Yep, exactly. I was just getting rough prices for parts as RCM had everything on a page. I think they're mega expensive personally, and I don't know much about them. Would rather stick to tried and true parts (Weisco Pistons, ARP studs, Carrillo rods etc.). I'm sure I did total overkill in my build estimations as well, but rather over estimate than under...of course I forgot about a new clutch as well 🙄 I'll be using Alyn at ASP as he's literally around the corner from me (2mi haha)

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8 hours ago, Seminole81 said:

Yep, exactly. I was just getting rough prices for parts as RCM had everything on a page. I think they're mega expensive personally, and I don't know much about them. Would rather stick to tried and true parts (Weisco Pistons, ARP studs, Carrillo rods etc.). I'm sure I did total overkill in my build estimations as well, but rather over estimate than under...of course I forgot about a new clutch as well 🙄 I'll be using Alyn at ASP as he's literally around the corner from me (2mi haha)

good choice, sound chap is alyn

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