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Old 04-25-2018, 11:35 PM   #1
VinceS2
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2005 EVO 8 WRX + STi
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Question '03 STi losing water badly, but head gaskets look fine. Ideas?

I pulled the engine convinced I had a blown gasket. A compression test check I did just when it first started said back left cyl down about 8psi on previous test but rest identical. Back then I could drive about 10 miles before temp rose and needed to put about a gallon of water in it. When that was down to 3 miles I figured better pull the thing and change both. ~60,000 miles on engine which I have had for the last 20,000 and running fine, until this happened.

Now I have it to bits I can't see any sign of hg leaking. WTF? This is my first steel gasket 'pull' but there is no discontinuity either side, whereas fibre ones get blown away. Back tracking, there is no mess anywhere like a blown hose, and I have pumped about 10 gallons through 'this hole' before giving up, worried about consequential damage as well as the extreme inconvenience.

Before I pulled it I knew I had little pressure in the system when (carefully!) took caps of on a hot stop. When I filled it and revved with the cap off the characteristic 'blubbing' of a hg failure happened, with dollops of air and rising levels. This continued to happen even if I held a slow hose (ie 'fake header bottle') on it to cleanse any air. No 'funny' puddles on pulling up or on the garage floor overnight after a refill day/s before, just overflow pipe, if anything. No billowing steam ever seen. So it's a hg, blown between a cyl and water jacket, what more is there to know??? Hmmm....

I can see the bore externals in the water jacket area and no sign of a cracked sleeve. Bores look good, although I do intend to change the rings as the compression figures are in the 130 - 135psi region. I also suspect the AVCS is not operating correctly (I degree checked the cams before disassembly and exhaust good but inlet all over the shop) and will check that when assembling, as well as new timing belt and all brgs incl water pump.

It's gotta be something simple, and of course I will check ten more times as MUST find a clear fault, it's a bloody big hole after all - it's gotta be there! But I am just wondering if there is some known sleazy failure mode I should check for but haven't thought of? All tips appreciated! Thank you.

Note, re the engine, it was properly tuned before discovering the low compression issue, so only got 210HP on a hub dyno at 21psi boost from 3,800 RPM. The set-up is:

-Full 2003 STi (Aus spec) engine & drivetrain mechanicals c/w TMIC
-Kinugawa 5+5 Billet TD05H-18G 7cm Housing Turbocharger with red 24psi actuator spring.
-ViPEC V7-9 ecu (updated to the latest firmware)
-APS High Flow Cold Air Intake
-Walbro high flow fuel pump
-3" XForce turbo back exhaust
-Fidanza Aluminium flywheel LAF8006 (5kg)
-RPM2133SSCC Stage 2 Clutch, pressure plate, throwout brg & spigot brg.
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Last edited by VinceS2; 04-26-2018 at 12:05 AM.
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Old 04-26-2018, 05:41 AM   #2
VinceS2
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Have a Nice Day? Traps for old players; Gashket Smashkett

Well I cut three corners off the gaskets and each layer has a continuous black ring around the cylinder, nothing to see here. No evidence of cracked heads.

Went checking hoses and there it was - top radiator hose has been rubbing on radiator and worn through, made a bit of a stain on radiator core, now I looked at it.

Wow eh.

All this work to do a 10 minute hose swap. If that doesn't take the cake for total whoopsies!!!

Aah well, I wasn't going to get much more than 5,000 miles out of the timing belt bearings so that's a much easier job while it's out. Plus the ring change, would really like to get off 130psi and go to 160+psi. And will learn about AVCS valve timing adjusting gizmo when I get to it.

OK, let's see how hard it is to get the pistons out through the top ... pretty sure I saw in the manual you could do that as I so don't feel like pulling off the bottom end just at the moment - rather leave as is and go lick my wounds, by getting it running again. Oh, and get a new hose....
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Old 04-26-2018, 10:24 AM   #3
Charlie-III
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Glad you found it.
Sucks you found it after the engine was out.

Yes, you can pull pistons without splitting the cases, pretty common method for all EJ Subaru engines regardless of displacement.

Your leak is why I like a cooling system pressure tester. Allows checking things with the engine off and coolant cool. Pressurize the system, watch leakdown, bend hoses as required to check for leaks.
Engine off also allows hearing small leaks like front of radiator behind AC condensor.
Clean engine also makes coolant more noticeable.

BTW, quite a few times I was never really sure where the leak was on a full metal gasket. Be sure to clean the head and block HG surface and check for flatness.
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Old 04-27-2018, 08:12 PM   #4
VinceS2
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I am now quite happy that I made this 'mistake'. Stripped heads and see exhaust valve seats were just starting to get into the 'expensive zone' where valves burn and seats get replaced. Handed over to Pryce race engines (Newcastle NSW) for a proper grind and get back in a week. This explains the 8psi drop on one cyl, it was about to go belly up!

The Pryce guy pointed to a couple of areas where the black ring on the head gasket seal was 'swimming' so he thought not too far before had the gasket fail anyway. OK, I'll take that too. But, while I am now the proud owner of a new hose, I am glad I didn't spot it and just kick the impending problem down the road to an undoubtedly less convenient time with more expense & hassle...
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Old 04-27-2018, 08:24 PM   #5
VinceS2
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Oh, and the nice people on eBay are sending me a universal cooling system checker. Thanks for pointing out that critical omission in the tool cupboard arsenal!!!
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Old 04-28-2018, 04:33 AM   #6
CosmoTheCat
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Pistons out the bottom? Do people attempt that?

You can't. They have to come out the top.
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Old 04-28-2018, 05:34 PM   #7
VinceS2
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Default While I've got it out...

Should I change the rear main seal? As in is it worth the bother to take clutch & flywheel off to do this job or do these seals not fail?

Same q with sump gasket really, not intending to pull any of this stuff off, but have a full engine seal kit just sitting there, looking at me....

Would you do it / is there a history of "when not if" that will just roll around? Am at 60,000 miles now....

Bores are perfect. No steps and good hone marks. Stuck a new ring in, mid stroke, and the gap is so small I didn't bother measuring it. Under 15 thou, prob about 10.
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Old 04-28-2018, 11:03 PM   #8
Charlie-III
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Sorta easy to do the rear main seal now. While the clutch is off, check the oil separator plate. It's likely metal but may be starting to leak, so reseal it.
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Old 04-29-2018, 09:16 PM   #9
VinceS2
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Smile ok, that oil separator plate tipped me over the edge...

I guess i knew the answer to my own q. This is now a full refresh minus bearings so do the lot. In any other motor I have pulled the only other thing going on in the back of the block is welsh plugs, which are a definite 'security' change. Subaru adds an osp, which I have never heard of but now read the horror stories around. Thanks for the tip.
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Old 04-30-2018, 02:49 AM   #10
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Behind the flywheel you'll have the rear main seal - they don't tend to leak, but if you're there, it's silly not to put one in - there's the wrist pin access plate that has an o-ring you'll want to replace, and the oil separator plate. If you reuse your fasteners, the one with the arrow pointing at it needs thread sealant as it will be a potential leak source.


Oh, Charlie - I've got a plastic plate sitting on my bench right now if you want it.


The other thing you're going to want to do is pull the oil pump off and make sure all of the screws on the back side are tight. There's an o-ring between the pump and block. The two wrist pin access plugs on the front have aluminum gaskets - typically I'll just reuse those and put thread sealant on them.
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Old 04-30-2018, 07:59 AM   #11
Charlie-III
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Cosmo, I only use the plastic ones for covering the hole of an engine on my stand.
I have swapped them out with either the cast version or the stamped version on all engines I have worked on.
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Old 04-30-2018, 09:09 AM   #12
VinceS2
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Thanks Cosmo, will do pins as suggested. I have a 12mm oil pump to go in. It is very well made, now I have read the gazillion pages on this topic and see what the casting etc issues are. Figured it is an older engine, not changing brgs, so a bit of extra flow cspability is good .vs. the risk of aeration. I also asked the race engines shop guy I dropped the heads off at if he would use it and got a definite yes - decision made! (validated really).
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Old 04-30-2018, 11:54 PM   #13
VinceS2
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Talking Hey, dodged another bullet...!!!

I was quietly pulling the pistons out to do the ring replacements and the second piston I pulled out only had a top circlip. Carbonisation was stopping the pin going out the other side, so no bore scoring. Lucky me!!! I have ordered a full genuine set from Subaru, grand total $18.88 (wow eh) and will pull the one I already did out again to give it good ones too.

Edit: The standard clips are 1.40mm wire to suit a 23.00mm pin. I did contact www.specialpistonservices.com first to get a set sent up but they use 1.50mm wire, so went genuine and will get in 24hrs ex Melb to Newcastle, not bad!

What this validates for me is 'good practice' when it comes to circlip installation. They should always be oriented so the 'arms' are sideways - ie the opening is facing up / down the bore (doesn't matter which). If the arms are facing up/down then every time the piston changes direction they see an inertial load. Until I saw this circlip missing I had always wondered if it really mattered, but the three clips I removed all went the wrong way, so I think that is all the evidence you need!

I probably won't bother to pull the sump off, or maybe I will. There will be two half circlip bits floating around in there somewhere, for sure! Which the pickup strainer will keep dealing with, as it has for gawd knows how many miles now.

Say pulling those pins sure can be a bitch. Might put up a pic later of the slide hammer attachment I cooked up to make it a snack...
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Old 05-01-2018, 03:57 AM   #14
CosmoTheCat
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Ah. Dude. Pull the pan off. The oil pickup tubes are known to occasionally crack - usually if the car was in a wreck, but not always. It would be silly not to at least check it. There are aftermarket alternatives that seem a little more stout.
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Old 05-27-2018, 09:42 PM   #15
VinceS2
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Talking Aah the joys of being a Virgin

Subaru mechanic that is. Once you have been through the first 'refresh' of one of these engines you get to see how plain effing dumb some of the questions you have are. The boxer engine is quite different to anything life circumstances have put in my way before, but all totally doable, and fairly straightforward in the end.

So I'm changing the rings and have the donc sitting on the flywheel. Hmm, how many of my questions does that little piece of info turn into total boners? Those that know can just shut up and giggle to themselves, OK. As I'm sure many readers did. When maybe a little good-natured mocking was called for, thanks for that...

The only build mystery that remains is where that missing circlip / two halves went? Never found it. Could be caked under the baffle in the sump I guess as hard to get your hand in there and air didn't blow anything out. Interestingly this is the only pin (left front) that was really hard to get out and I made the slide hammer extension to pull through the bit of buildup. The others got ejected half across the garage once I got the bent coathanger hooked up and gave them a reef. Pickup tube was in excellent condition so back in it went.

New ring gaps all well within spec so not much block wear going on. Didn't think to check old ones... but who cares!

Live and learn, but all good. Not there yet as still waiting for bits, but much easier to do this second time around if the bug bites for more HP, and the capacity to fund it comes along!
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Old 06-10-2018, 01:22 AM   #16
VinceS2
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Cool Well that was worth doing!!!

Gotta love it when you pull an unknown-to-you motor into tiny little bits then reassemble it and broom, instant start. Goes better too! Which was the whole point, apart from fixing the water leak and, as it turned out, the whole stitch in time before the missing gudgeon circlip gouged the bore, or the uneven leaky exhaust valve seats started burning valves / seats. I suspect the 130psi cranking compression is over 170 now, where it should be, if the seat-of-the-pants dyno is anything to go by***8230;

I need to run the rings in before getting the tuning re-done for how it is now, and saw a fair bit of oil mist out the back on WOT so may have an issue there to sort first (only 25km so far, 3 heat cycles) but it does seem to be diminishing, plus want to check the compression to get hard numbers. Need to find an excuse to go for a decent drive and vary the load a bit and see where she settles at.

For now, I have added 5psi to fuel pressure (60psi / 50psi vac hose off / on at idle, on pink sTi injectors) and stuck on a PLX DM-6 gauge with Air-fuel ratio, exhaust gas temp (at 2-4 manifold joint) and Air Inlet temp (to throttle body) so I can check for obvious problems. If you don't know about this nifty gauge system, see http://www.plxdevices.com/PLX-MultiG...sors-s/108.htm.

The thing that tells me more than anything else that I MUST get a new tune is the way the turbo snaps up to 25psi now, around 3k, whereas it used to not get there until much later. I reckon I'm close to the desired 300HP, but not game to 'let it go' - as soon as it 'snaps on' to do a runner I ease off!!! And that is when a few swirls of smoke turn up behind. I definitely did space the ring gaps evenly around the pistons, but where exactly they were in relation to mother earth, not so sure. This I have read elsewhere here can be a bit of an issue. Personally I am hoping it is just burning off oil I put / spilled there... There was a fair bit coating the turbo / sTi TMI which can't be cleaned off (just wipe openings); hopefully the new catch can putting all vents to PCV direct should eliminate that happening again, once it is all gone...

Last edited by VinceS2; 06-10-2018 at 01:53 AM.
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Old 10-18-2020, 05:53 PM   #17
VinceS2
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Default Two years on, 4 wheel spinning bliss!

Just for posterity as I was looking for pics and noticed this one never got 'closed off'. The misting problem was a badly plumbed oil catch can, written up in great detail here: https://forums.nasioc.com/forums/sho....php?t=2879743. Two years on, the vehicle runs like a beauty. Recently I had to tow a heavy trailer up a steep driveway and it broke away, spinning all wheels for about 15 seconds while it got the job done and made a bunch of smoke along the way! It was quite a sensation of 'raw power' and I was pretty chuffed that I built this motor.

I never did get a retune, but added a fuel pressure regulator and a PLX gauge with inlet, AFR & exhaust sensors. Initially bumped the fuel pressure up 10 psi and all it did was burn more fuel. Backed it off to 5 then back to stock. The gauges tell me there is nothing wrong with the tune and if I have left anything on the table I don't care as it is way past 'good enough' as it is. I have since purchased a Golf R as the platform that will give me something to play with going into semi-retirement stage of life, whenever that happens but I can see it from here. So this car will come up for grabs on Gumtree in about a week when I finish with a couple of minor tidy-up issues. Oh, and I want to run it over a dyno first, just to see what the heck I have loved driving all these years!
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