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2004 Subaru Impreza WRX STI
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Discussion Starter · #1 · (Edited)
Hello everyone so sadly I've had headgasket failure on my built 04 STI, so far I've almost got the heads off, I was just wondering since I've got the engine out of the car now

What do you guys reccomend I go ahead and change? The new engine only has 7500 miles on it.

Long story short the " conservative" dyno tune was causing as high as negative 8 knock feedback. When I called the shop they told me to expect some negative knock feedback as I have a loud exhaust, invidia high flow catted downpipe and gymkhana exhaust.... when you pay as much as you pay to have someone else build it and tune it, you tend to wanna take their word for it. I did and now the cars shooting smoke out of the exhaust like a jamesbond movie and the coolants bubbling as well as coolant Is literally leaking through my headers... ohh exhaust leak I could never find...

They also don't wanna take any responsibility and told me, it must be user error and I must pay 2500 to 5k to fix it cause I most likely cracked a head or just got the car too hot...

So since I've got the engine out what do you guys suggest I do maintenance wise, I was gonna do headgaskets, valvecover gaskets, and machine/ port the heads.

I know under regular circumstances say 50k miles or 100k miles you'd do Timing belt, water pump etc. But it's only 7500 miles which Is why I ask.

I also sadly didn't do a compression or leakdown test before pulling the engine out sadly. And when the headgaskets did go I had the car towed to the shop where it sat for a week cause they refused to do anything to it cause if it were they're fault the engine would have let go at 3500 miles on the dyno not at 7500 miles while I'm driving it home. So for a week and a half the car sat with the coolant mixed with oil in it and then I drained the oil.

Should I pull apart the WHOLE short block and do/ check bearings ?

I can post the receipt for those wondering the build.
 

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I see you're using je pro seal HG. I had a similar failure but my engine had 1500 miles on it.

I went with oem HG on the rebuild and it's held longer than the expensive JEs did.

I recommend OEM HG.

Also, I wouldn't pull the motor apart. Get yourself a factory service manual and go over it. There is no reason to tear the engine apart for a simple HG failure. Typically HG failures don't damage the motor assuming it didn't overheat.
 

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I see you're using je pro seal HG. I had a similar failure but my engine had 1500 miles on it.

I went with oem HG on the rebuild and it's held longer than the expensive JEs did.

I recommend OEM HG.

Also, I wouldn't pull the motor apart. Get yourself a factory service manual and go over it. There is no reason to tear the engine apart for a simple HG failure. Typically HG failures don't damage the motor assuming it didn't overheat.
Same thing with me. je pro seal didn't last very long for me either. I had signs of a head gasket failure within the first 2 hours of the build but some how managed to make due with it for about 6-7k miles. Went with a fire ring head gasket and will never use anything less
 

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Discussion Starter · #5 ·
Same thing with me. je pro seal didn't last very long for me either. I had signs of a head gasket failure within the first 2 hours of the build but some how managed to make due with it for about 6-7k miles. Went with a fire ring head gasket and will never use anything less
Damn that makes sense, however I do have another question though, so I finally did get both heads off and this is what my pistons look like

I think the tune they put on the car while it was on the dyno was @$$...
This engine only has 7500 miles on it and they said the tune was conservative. On 1440cc injectors blouch dom 2.5xtr is only pushing 24 psi

Below is cylinder 2 and 4
right after doing a pull I got a cylinder 1 misfire.
Automotive tire Wheel Bicycle part Motor vehicle Rim

Automotive tire Motor vehicle Automotive design Alloy wheel Rim


a closer look at cylinder 1 ( BELOW)
Automotive tire Motor vehicle Water Automotive design Liquid

Wheel Tire Automotive tire Tread Motor vehicle


Below is cylinder 1 and 3
Optometry Automotive tire Bicycle part Engineering Gear
 

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Damn that makes sense, however I do have another question though, so I finally did get both heads off and this is what my pistons look like

I think the tune they put on the car while it was on the dyno was @$$...
This engine only has 7500 miles on it and they said the tune was conservative. On 1440cc injectors blouch dom 2.5xtr is only pushing 24 psi

Below is cylinder 2 and 4
right after doing a pull I got a cylinder 1 misfire.



a closer look at cylinder 1 ( BELOW)



Below is cylinder 1 and 3
Could be the tune, but tbh, it looks like coolant entered that cylinder and cleaned out the piston with some serious steam 😂
 

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Discussion Starter · #7 ·
Same thing with me. je pro seal didn't last very long for me either. I had signs of a head gasket failure within the first 2 hours of the build but some how managed to make due with it for about 6-7k miles. Went with a fire ring head gasket and will never use anything less
Since I am replacing the headgaskets rather early, I shouldn't need to replace the waterpump, Timing belt/ tensioners etc?

Just valve cover gaskets, other gaskets( downpipe to turbo/ upipe gaskets) , head gaskets, I'm currently getting the heads machined at the machine shop, and any stripped bolts etc.

I should be fine re using the old waterpump, thermostat,, etc Since everything still only has 7500 miles on it?
 

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Since I am replacing the headgaskets rather early, I shouldn't need to replace the waterpump, Timing belt/ tensioners etc?

Just valve cover gaskets, other gaskets( downpipe to turbo/ upipe gaskets) , head gaskets, I'm currently getting the heads machined at the machine shop, and any stripped bolts etc.

I should be fine re using the old waterpump, thermostat,, etc Since everything still only has 7500 miles on it?
I would get new gaskets for every thing though.

I would just change the thermostat, it's cheap haha
 
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