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Old 12-24-2017, 03:58 PM   #1
brecks
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Member#: 435142
Join Date: Nov 2015
Chapter/Region: MWSOC
Location: Commerce Twp, MI
Vehicle:
2004 STi
Java Black Pearl

Default Bubbles in Coolant Overflow/Odd Temps

Hey guys, I have a 2004 STi with the following modifications:
-Bosal Twin Tip 3” CBE
-GrimmSpeed Limited Catted Divorced 3” Downpipe
-CNT ELH (ceramic coated)
-Grimmspeed Ceramic Coated EWG Up Pipe
-Tial MVS 38mm EWG
-BCP X500 8cm turbo (turbo blanket)
-IAG Performance Competition Series AOS
-NGK One Step Colder Spark Plugs
-IAG 8mm Phenolic Spacer
-KStech TGV Deletes
-KStech 73mm Intake
-Grimmspeed EBCS
-Perrin Turbo Inlet 2.4”
-ID1050X and Top Feed Rails/Lines
-DW300 340lph hardwired
-Modded Stock BPV
-Mishimoto FMIC
-Cobb Accessport V3
-Factory Oil Cooler Deleted

The block was stock, stock cooling system with the exception of the mishimoto coolant overflow that came with the FMIC kit. At 99k miles, I blew a piston ring land and the engine was pulled, rebuilt (OEM not built, dumb I know but I didn't have the funds) and everything was put back together. Car has been running fine and now has 100k miles, except for two things I noticed that have stumped me:

1. My accessport has been reading slightly higher coolant temps than normal, which I found strange. In the summer before the piston cracked, by average coolant temps cruising were about 184-186. Temps wouldn't really ever change unless I was sitting still, but temps would drop back down once I got moving. Now, with everything back together, (in the winter) cruising temps are 196 in the city, but get up to 201-203 in high gear lower rpm (highway driving). Under WOT the temps will drop quickly, lowest I've seen them go was 178 during a pull. This led me to believe there was an issue with the cooling system, though I didn't have one before the engine was rebuilt.

2. The other day, I noticed that there was some coolant that had vented out of my overflow, so I got the car up to temp, opened the overflow, and didn't see any bubbles. Revving the car up to 4K gave way to 5 or 6 pea-sized bubbles in the overflow. Clearly this would indicate that some coolant is being pushed under high load.

I have yet to change any of the cooling parts due to the fact that they all worked prior to the engine being rebuilt. Originally I was thinking the thermostat was stuck partially open, causing the temps to stay a bit high when the RPMs were low, and cooling too quickly when the RPMs were high. The bubbles made me start to consider if it is a head gasket issue, and that the new ones were not properly installed. However, I wouldn't think temps would drop under WOT with a leaky HG. The car runs completely fine, without the accesport to show me the temps and visually seeing the bubbles in the coolant overflow, you'd think there's nothing wrong with the car. I've tried bleeding the air out of the cooling system several times, and while it COULD still have air, I highly doubt it. I know that leaking head gaskets don't always lead to exhaust smell in the overflow, visual coolant in oil/vice versa or overheating, but my car has none of these symptoms other than the slightly higher temp. Could all of this be attributed to a small head gasket leak? Should I even bother replacing the thermostat? Test the coolant for exhaust gas? Any info would be greatly appreciated as this has really been testing my knowledge! Thanks
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Last edited by brecks; 12-24-2017 at 04:36 PM.
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Old 12-24-2017, 04:05 PM   #2
relative4
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2005 LGT 5MT Stg2

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Exhaust gas leak tester
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Old 12-24-2017, 10:51 PM   #3
europa
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The following could be tested: compression, leak down and coolant pressure (leak at cap seal and/or hose to the reservoir).
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Old 12-25-2017, 11:41 PM   #4
hondaeater69
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1998 RS

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hg issues can present in many different ways. sometimes under boost, sometimes only when the car is idled etc. replicate when you can push some bubbles out of the overflow and block test the overflow. pushing coolant out of the overflow is a telltale HG issue.
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Old 12-27-2017, 04:21 PM   #5
Max Capacity
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Join Date: May 2007
Chapter/Region: NESIC
Location: Tolland, CT
Vehicle:
05 LGT,09 SpecB
Black/silver

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One important thing I see missing for your build is "APR Head studs".
Don't forget to use then next time.

Those a great tune are the way to keep these engine together. You really don't need a built block for under 350whp or so.
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Old 01-03-2018, 06:11 PM   #6
brecks
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2004 STi
Java Black Pearl

Default

Thanks for the replies guys. The car does push some coolant out of the overflow so my bet is with the head gasket
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Old 01-03-2018, 06:15 PM   #7
brecks
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Java Black Pearl

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Quote:
Originally Posted by Max Capacity View Post
One important thing I see missing for your build is "APR Head studs".
Don't forget to use then next time.

Those a great tune are the way to keep these engine together. You really don't need a built block for under 350whp or so.
There are two schools of thought on this issue. Some people will reuse the stock head bolts with no issues, some use ARPs and HAVE issues (usually do to improper install). Now I can't say I know what the issue is and whether or not head studs will fix my issue, but I can say that as $200 insurance, it's probably a good idea. Btw, car made 410whp on 93 and 450whp on E85
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Old 09-07-2019, 12:13 PM   #8
brecks
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Java Black Pearl

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Update: for those who may be experiencing similar issues, the car just needed some fancy bleeding due to IAG AOS
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Old 09-09-2019, 10:33 AM   #9
BootsJunkie
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WRB

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Quote:
Originally Posted by brecks View Post
Update: for those who may be experiencing similar issues, the car just needed some fancy bleeding due to IAG AOS

Any deets on this "fancy" bleeding procedure?

I too think my problem is simply not bleeding correctly (even with a Lisle spill-free funnel) and I don't think it's HG's b/c they're brand new JE pro-seals with ARP's and an IAG AOS.
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Old 09-09-2019, 08:06 PM   #10
stu
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SL performance, 2.34 LR

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If you have HG issues you will overheat due to pushing coolant out the overflow. If you continue to get air in the system after a bleed then you have a HG issue. If your temps are acting weird check your thermostat. But 205 is not that high especially if you have the AC on and its hot out. Now if it stays 205 for awhile something is wrong with the thermostat not opening all the way. I've watched it happen with 3 stock thermostats, opening at different temps and one only half way. For a proper bleed I let the fans cycle twice.
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Old 09-09-2019, 08:09 PM   #11
Waddlz
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I recently had to replace my thermostat cause it wasn't opening all the way. I hit 237 coolant temps on the drive home and the needle started moving to the H.

this was in 100 degree heat with AC on full blast in stop and go traffic, with a FMIC.
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Old 10-15-2019, 09:08 PM   #12
brecks
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Location: Commerce Twp, MI
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2004 STi
Java Black Pearl

Default

Quote:
Originally Posted by BootsJunkie View Post
Any deets on this "fancy" bleeding procedure?

I too think my problem is simply not bleeding correctly (even with a Lisle spill-free funnel) and I don't think it's HG's b/c they're brand new JE pro-seals with ARP's and an IAG AOS.
Sorry to be getting back so late. But I also used one of those Lisle funnels, it just required me to lift the car up in the air. I think the way I had my AOS mounted made it the "highest point" in the cooling system. But simply bleeding it with the Lisle, lifting up the front of the car some, and letting the fans cycle a few times with the heater on did the trick for me
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Old 10-16-2019, 11:10 AM   #13
BootsJunkie
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WRB

Default

Quote:
Originally Posted by brecks View Post
Sorry to be getting back so late. But I also used one of those Lisle funnels, it just required me to lift the car up in the air. I think the way I had my AOS mounted made it the "highest point" in the cooling system. But simply bleeding it with the Lisle, lifting up the front of the car some, and letting the fans cycle a few times with the heater on did the trick for me

Gotcha. And is your AOS mounted on the passenger strut tower? Or in the center off the pitch stop?
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Old 10-31-2019, 01:28 PM   #14
brecks
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Join Date: Nov 2015
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Vehicle:
2004 STi
Java Black Pearl

Default

Quote:
Originally Posted by BootsJunkie View Post
Gotcha. And is your AOS mounted on the passenger strut tower? Or in the center off the pitch stop?
Passenger strut tower, but on the bracket there is some adjustment with the Allen bolts to make it sit higher or lower, and I have it sitting as high as possible, to encourage oil to drain out of it most efficiently. Consequently, that make it a bit difficult to fully bleed!
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