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View Poll Results: Which repair option
Replace gaskets 0 0%
Replace gaskets and use timeserts and/or o-ring 2 20.00%
Outfront closed deck 1/2 inch studs case halves 8 80.00%
Voters: 10. You may not vote on this poll

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Old 06-28-2019, 08:06 AM   #1
Atheba
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Default Advice needed - another pushing coolant at 700+ whp thread

Heya,

So I need some expert advice on what to do.

Car details:
2007 Subaru STi
BW 9180
Golden Eagle sleeved block & no o-ring
720 whp @ 7000rpm on e85 29psi boost 5750 ft above sea level
ARP 625+ studs

History:
From day one the car was pushing coolant into the overflow. There were a few areas that I have fixed that were leaking. Replaced the wg return line that had a slight tear in it. Replaced the radiator cap + drain plug.

The car also had some fueling issues that I sorted out. The oem fuel controller was initially used on the lift pump and after a short while fuses started to blow. I bypassed the controller so that the pump is hard wired. The two main pumps are running in a radium engineering surge tank with the second pump triggered to run above 0.8 bar boost. The second pump was hard wired but I decided to move this onto the secondary controller that is used by the first main pump. Fuel issues seem to be sorted at this point but I have ordered a fuel pressure sensor that will be monitored by the ecu going forward.

I also had some misfire issues and replaced the coil packs with the okada units. Misfires have been sorted.

Problem:
The car was initially pushing a slight amount of coolant and this has become a bit worse at this point. I suspect the head gasket has gone after the fuel related issues. Car still runs great and pulls strong but I havent had a chance to check power output on the dyno. Car doesn't overheat and stays below the half mark on the gauge. I am running without a thermostat so this might be keeping temps in check. Coolant doesnt bubble at idle or when car is revved but I can smell fuel in the radiator and the overflow has what looks like fuel residue.

I am most likely going to need to get the motor pulled and gaskets replaced at a minimum. I'm unsure if the initial pushing coolant was caused by water leaks or heads lifting. What is my best option? Id hate to replace a gasket and have the same issue a couple of months later.

Option 1:
Replace gaskets

Option 2:
Replace gaskets and use timeserts and/or o-ring for additional sealing strength

Option 3:
Order outfront closed deck 1/2 inch stud case halves and transfer my rotating assembly

I'm stuck between options 2 & 3 and would appreciate help from folks that have dealt with these issues.

Thanks.

P.s. I initially planned to turn the boost up another 5 psi but am probably going to leave the car at this level as I want to start with another build next year.
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Last edited by Atheba; 06-28-2019 at 08:11 AM.
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Old 06-28-2019, 07:26 PM   #2
user1029
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IAG closed deck with 1/2" Head studs and Firelock Headgasket. I love to see you push coolant after that
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Old 06-29-2019, 03:10 AM   #3
Atheba
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Quote:
Originally Posted by user1029 View Post
IAG closed deck with 1/2" Head studs and Firelock Headgasket. I love to see you push coolant after that
The Outfront block is the same? I have 99.5 pistons currently. The IAG only comes in a 99.75 bore?

EDIT: My mistake - I see they have their own firelock HG.

Whats your experience with this? Also, pinned mains? Are they worth the extra spend?

Last edited by Atheba; 06-29-2019 at 06:37 AM.
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Old 06-29-2019, 09:12 PM   #4
kp05sti
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You don't need to replace the case halves to do half inch studs. Last I checked outfront has a kit to install the studs yourself OR you can send them your case to be machined for the studs. If you do a new case you will need to reset your main bearing clearances. You will also need to machine your heads for the studs either way. If it were me Id go outfront CD and half inch studs since thats what I am running right now at 700+whp with no issues.
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Old 06-30-2019, 10:56 AM   #5
user1029
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Quote:
Originally Posted by Atheba View Post
The Outfront block is the same? I have 99.5 pistons currently. The IAG only comes in a 99.75 bore?

EDIT: My mistake - I see they have their own firelock HG.

Whats your experience with this? Also, pinned mains? Are they worth the extra spend?
I have pinned mains, 1/2 studies, oring gasket. I haven’t pushed a drop of coolant at 38psi for the past 40k miles
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Old 06-30-2019, 02:48 PM   #6
Atheba
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Quote:
Originally Posted by kp05sti View Post
You don't need to replace the case halves to do half inch studs. Last I checked outfront has a kit to install the studs yourself OR you can send them your case to be machined for the studs. If you do a new case you will need to reset your main bearing clearances. You will also need to machine your heads for the studs either way. If it were me Id go outfront CD and half inch studs since thats what I am running right now at 700+whp with no issues.
Logistics is a bit of a problem - Im in South Africa and getting new case halves might be more economical than sending mines for machining. I'm going to find out from the tuner about getting these installed locally. I want to be certain that the machine work will be up to scratch.

Would I be able to get away with o-rings only? How critical is pinning the mains at this power level? Do you have pinned mains & o-ringed block?

With heads lifting will there be a noticeable power loss? At the moment the car runs great and feels strong. Also there is no overheating - I need to get the coolant system pressure tested as a start.

Last edited by Atheba; 06-30-2019 at 02:56 PM.
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Old 06-30-2019, 02:53 PM   #7
Atheba
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Quote:
Originally Posted by user1029 View Post
I have pinned mains, 1/2 studies, oring gasket. I haven’t pushed a drop of coolant at 38psi for the past 40k miles
That is impressive! Speaks volumes for IAG's work.

What has me worried is that the oem cylinder liner is still used with the CD inserts and you can run into a problem like this.

Also not forgetting the 1/2 inch studs pulling threads issues that people have experienced.

As much fun as the car is at the moment - I'm considering replacing gaskets and torque limiting the motor to 500 ft/lbs. I want to start a build with a 6 cylinder and would like to move on to my next project.
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Old 06-30-2019, 02:56 PM   #8
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I see IAG recomends 99.75 bore on their case? Is this the same with the Outfront case? Or could I use my 99.5 with new rings and a hone + set main bearing clearances?
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Old 06-30-2019, 03:55 PM   #9
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I believe the 99.75 bore is because they have to account for boring and/or honing after the close deck process, with torque plates applied. You can't just close deck the block and leave the original 99.5 bore and expect it to be spot on. There will be dimensional changes to the inner bore, up top where the close deck inserts have been pressed in.

My guess at your power level is that stainless o-rings and new gaskets would do the trick. Not sure why all the expense of a completely new case would be needed...you already have a sleeved case. Just get the o-ring work done, and have your block honed with torque plates. Then you will have a proper seal and boost will never be an issue.


If you 1: lived in the USA, 2: didn't have a block at all, 3: yours was destroyed by a pissed off piston rod, or 4:just felt like throwing the money you've spent on your current case away...then buying an Outfront or IAG close deck converted block would be a great option.

Last edited by 2slofouru; 06-30-2019 at 04:01 PM.
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Old 06-30-2019, 04:02 PM   #10
Atheba
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Quote:
Originally Posted by 2slofouru View Post
I believe the 99.75 bore is because they have to account for boring and/or honing after the close deck process, with torque plates applied. You can't just close deck the block and leave the original 99.5 bore and expect it to be spot on. There will be dimensional changes to the inner bore, up top where the close deck inserts have been pressed in.

My guess at your power level is that stainless o-rings and new gaskets would do the trick. Not sure why all the expense of a completely new case would be needed...you already have a sleeved case. Just get the o-ring work done, and have your block honed with torque plates. Then you will have a proper seal and boost will never be an issue.
I agree with this - Any need for the 1/2 inch headstuds? The block will have to come apart and go for o-ring machine work.
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Old 06-30-2019, 04:13 PM   #11
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Quote:
Originally Posted by Atheba View Post
I agree with this - Any need for the 1/2 inch headstuds? The block will have to come apart and go for o-ring machine work.

I would get 13 or 14 done, if you're already doing the o ring work. The larger OD of the studs will spread the threads load out and be less likely to pull. Pinned mains would be a good idea as well, since it will all be bored and honed in one trip. Keeps you from wishing you'd done it later on if/when you decide to go bigger on the turbo and injector end. Just opinion based on what I've seen here over the years, but there are always blocks and turbos for sale...because people decide to go bigger. Already running sleeves, your block doesn't need much more to be at the top end.
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Old 06-30-2019, 04:29 PM   #12
Atheba
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Quote:
Originally Posted by 2slofouru View Post
I would get 13 or 14 done, if you're already doing the o ring work. The larger OD of the studs will spread the threads load out and be less likely to pull. Pinned mains would be a good idea as well, since it will all be bored and honed in one trip. Keeps you from wishing you'd done it later on if/when you decide to go bigger on the turbo and injector end. Just opinion based on what I've seen here over the years, but there are always blocks and turbos for sale...because people decide to go bigger. Already running sleeves, your block doesn't need much more to be at the top end.
Thanks. This is some good advice. I'm going to speak to engine builder and tuner and see what options I have.
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Old 07-01-2019, 11:25 PM   #13
user1029
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Quote:
Originally Posted by Atheba View Post
That is impressive! Speaks volumes for IAG's work.

What has me worried is that the oem cylinder liner is still used with the CD inserts and you can run into a problem like this.

Also not forgetting the 1/2 inch studs pulling threads issues that people have experienced.
I had the same concerns going big studs and closed deck but then I remembered that IAG defies physics with their engineering
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Old 07-02-2019, 05:34 AM   #14
Atheba
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Originally Posted by user1029 View Post
I had the same concerns going big studs and closed deck but then I remembered that IAG defies physics with their engineering
I'd swear that you are a sales rep for IAG. lol.
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Old 07-02-2019, 05:36 AM   #15
Atheba
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On a side note - HG or heads lifting would always have a loss of power when on boost resulting in overheating thereafter?

I have none of this but coolant is missing?

Last edited by Atheba; 07-02-2019 at 10:31 AM.
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Old 07-02-2019, 11:23 AM   #16
TDagen
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My engine never overheated with the heads lifting, but it would blow the coolant overflow cap right off and spray coolant out. Like you, I also never noticed any type of power loss.
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Old 07-02-2019, 04:23 PM   #17
Atheba
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Originally Posted by TDagen View Post
My engine never overheated with the heads lifting, but it would blow the coolant overflow cap right off and spray coolant out. Like you, I also never noticed any type of power loss.
Ok thanks. I'm going to trawl through my logs and check if I can spot anything. Boost/manifold pressure would probably go flat at a certain point in this scenario?

I think I need to also re-check my entire cooling system setup:

1. Overflow is deleted.
2. My turbo tank is deleted - hence no water is being drawn back into the system from the overflow.
3. My heater core is bypassed but it looks like the return line for this has been deleted i.e. the one that supposed to run to the water pump. It looks like the feed line is used to fill a vw coolant bottle.

Is there an online resource where I can check every coolant port on the block /head and where they supposed to route to? And the coolant manifold?
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Old 07-03-2019, 10:58 AM   #18
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I doubt you'll see anything boost wise in the logs that will show the HG issue. Coolant temp is probably the only sensor that might help. Might be worth looking into a coolant pressure sensor in the future which will show the HG failing.

coolant diagram
https://forums.nasioc.com/forums/sho....php?t=2794899
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Old 07-03-2019, 02:11 PM   #19
Atheba
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Quote:
Originally Posted by Paul View Post
I doubt you'll see anything boost wise in the logs that will show the HG issue. Coolant temp is probably the only sensor that might help. Might be worth looking into a coolant pressure sensor in the future which will show the HG failing.

coolant diagram
https://forums.nasioc.com/forums/sho....php?t=2794899
This is a useful idea - I've got a pressure sensor and an arduino laying around. Will put something together to view this on the laptop to confirm.

How much of a spike in pressure should I be looking at to indicate hg failure/heads lifting?

Last edited by Atheba; 07-03-2019 at 04:55 PM.
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Old 07-04-2019, 09:55 AM   #20
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You’ll have to do your own testing most likely since I assume everyone’s readings are different. I’d hook the sensor up, do some logging to see what’s “normal” then set a safety a little bit higher
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Old 07-04-2019, 03:04 PM   #21
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Quote:
Originally Posted by Atheba View Post
This is a useful idea - I've got a pressure sensor and an arduino laying around. Will put something together to view this on the laptop to confirm.

How much of a spike in pressure should I be looking at to indicate hg failure/heads lifting?

I'm guessing an abnormal fluctuation would be rapid spikes in the realm of milliseconds, whereas normal would be a slow rise/fall in spans of seconds.

Why are you not using a radiator cap and reservoir that would allow excessive pressure to vent and be reclaimed during cooling? This would also ensure air is eventually thoroughly purged (assuming no headgasket or external system leaks).
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Old 07-04-2019, 04:37 PM   #22
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Quote:
Originally Posted by 2slofouru View Post
I'm guessing an abnormal fluctuation would be rapid spikes in the realm of milliseconds, whereas normal would be a slow rise/fall in spans of seconds.

Why are you not using a radiator cap and reservoir that would allow excessive pressure to vent and be reclaimed during cooling? This would also ensure air is eventually thoroughly purged (assuming no headgasket or external system leaks).
Makes sense - I would expect a sharp rise above the radiator cap rating on boost.

This is unintentional. Im going to switch this to the oem setup. And I am going to run the 1.3 bar radiator cap as I have the aluminium radiator.
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Old 07-04-2019, 04:39 PM   #23
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Quote:
Originally Posted by Paul View Post
You’ll have to do your own testing most likely since I assume everyone’s readings are different. I’d hook the sensor up, do some logging to see what’s “normal” then set a safety a little bit higher
I'm going to run this on the ecu after my testing.
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Old 07-05-2019, 10:45 AM   #24
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What head studs are you currently running?
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Old 07-05-2019, 12:51 PM   #25
Atheba
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Originally Posted by 1qukSti07 View Post
What head studs are you currently running?
The ARP 625+ stock sized studs.
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