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Old 07-08-2008, 11:34 PM   #1
SubieFan98
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Question wtf car overheating after header install...help plz

Hey everyone, I have a 98 2.5RS and just installed Cobb equal length headers and Cobb cat back system. Right away the car starting overheating and spewing coolant tru the overflow tank if driven hard. Now i thought it was the head gasket but there isnt any white smoke from the tailpipe, coolant in the oil or any bubbles in the rad. I had the rad flushed and replaced the thermostat to no avail. Had the block leak down tested at the local subie dealership and they said the headgaskets are fine. So now im out of ideas, anyone kno what this could be or how to fix it? Would i need a higher temp rating thermostat cause the headers would cause it to run hottter? And would a intercooler poossibly fix my problem and if so could anyone suggest where i could get one? Would really appreciate some feedback cause im really frustrated seeing as ive had the car 3 weeks!!!
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Old 07-09-2008, 12:06 AM   #2
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did you heat wrap anything before you put it on?? i would try that as the factory headers had a heat sheild on them.... also are you fans kicking on..have you let the car idle to see if they do???
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Old 07-09-2008, 01:08 AM   #3
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Not sure how the Cobb exhaust is, but i would assume it's made from stainless steel. As a result, they get hotter release more heat than the OEM cast ones, simply cause they are thinner. This does influence the temp. in the engine bay, but by no means to the point of overheating.

It might just be a coincidental cooling issue. Water pump failure? thermostat? One way to check the latter is to start the car when COLD and unscrew the rad cap. Nothing should be flowing for a little while as the thermostat limits the circulation out of the radiator. Might also be a water bubble. Happends on imprezas, and it results in overheating. Draining the coolant and refilling it helps.

Take it one step at a time, but I'd focus on diagnosing the the cooling system first..
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Old 07-09-2008, 01:13 AM   #4
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most likely a heating issues. but check your coolant for flakes, worse case is it is a head gasket.
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Old 07-09-2008, 07:24 AM   #5
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I'd call it coincidental. The header isn't going to cause the car to overheat unless you disturbed something in the cooling system while putting the header on. That would be somewhat rare since you aren't anywhere near anything cooling related. That said....it's a 98RS, EJ25D.....you can almost bet it's headgaskets until you prove it not to be.

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Old 07-09-2008, 10:10 AM   #6
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alright well the fans are working and i re-bled the cooling system to get any air bubbles out and its still doing it. So its gotta be the headgasket right? but i was told by the dealership that the block held pressure in a leak down test fine
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Old 07-09-2008, 10:17 AM   #7
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If you have the old headers, put them back on and see if it does it still. If it does, I'm thinking you may have cut/melted/forgot/bludgeoned something liek the thermostat, some temp sensor, etc.
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Old 07-09-2008, 05:15 PM   #8
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Quote:
Originally Posted by SubieFan98 View Post
alright well the fans are working and i re-bled the cooling system to get any air bubbles out and its still doing it. So its gotta be the headgasket right? but i was told by the dealership that the block held pressure in a leak down test fine
Ask them to do a carbon test on the coolant. You may not see it, they may not see it....but the gaskets may very well be failing on one side.

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Old 07-10-2008, 11:41 AM   #9
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Quote:
The header isn't going to cause the car to overheat unless you disturbed something in the cooling system while putting the header on.
true, but my mechanic did something to my cooling system when i wanted a simple oil change.
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Old 07-10-2008, 12:15 PM   #10
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+1 on the carbon test on the coolant. Sounds like internally blown headgaskets.

How that happened after doing headers... no idea. coincidence?
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Old 07-10-2008, 12:22 PM   #11
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I'd go back to the mechanic and ask what he did to the cooling system, citing your new problem. It may or may not be related...but if he was the last one to touch it, it makes sense to pick his brain about it.
Quote:
Originally Posted by 2.5wagonkid View Post
true, but my mechanic did something to my cooling system when i wanted a simple oil change.

Jay
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Old 07-10-2008, 02:03 PM   #12
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Did you drive the car harder than normal after getting the headers installed?

Head gaskets on the verge of failing would probably kick the bucket with a short period of hard usage. If you were blasting around after installing your new exhaust (like I would be too!) then maybe the higher load on the cooling system and higher combustion temps would have done them in.

I hope that's not what it is, but I've dealt with head gaskets twice on my motor and that is what it sounds like on yours.

Good luck!
Aaron
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Old 07-10-2008, 02:43 PM   #13
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I agree that it's probably a bad H20 pump or your H.G.'s have an internal leak.
I've been runnin' my Cobb Jet Hot Coated E.L. Headers with hi-flow cat. for thousands and thousands of miles for years with no problems. FWIW
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Old 07-10-2008, 03:28 PM   #14
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A bad waterpump will be known instantly. They squeal like a sleeping cat, until the timing belt breaks and introduces valves to pistons.
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Old 07-10-2008, 03:49 PM   #15
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well turns out to be the headgaskets after all lol. Turns out thats the 98 RS motor, a EJ25D was notorious for headgaskets. Subaru now has a replacement gasket that is thicker because the old 3ply ones were prone to failure. And yes prob with the headers is added more stress to them cause they were the orig's which just cause it to go after the modifications. And apprently they only leak tru the waterjacket which is why there is no coolant in the oil, a sweet smelling exhaust or bubbles in the rad.
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Old 07-10-2008, 05:11 PM   #16
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I just finished doing my head gaskets on my 97 Legacy GT. It had the same symptoms as yours. This was my first time working on a Subaru. I have been an American hot rodder for decades and have done everything possible to them.

Some things were easier than expected some things harder. There are some good threads on doing them yourself.

I had to figured out a couple of things to make it easier.

One thing I had to do to get the bolts holding the drive plate to the flywheel. I unbolted the intake manifold bolts and then lifted it enough so i could get a long extension straight from the front. I couldn't get the bolts off the the access port.
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Old 07-10-2008, 05:19 PM   #17
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Quote:
Originally Posted by SubieFan98 View Post
And apprently they only leak tru the waterjacket which is why there is no coolant in the oil, a sweet smelling exhaust or bubbles in the rad.
I don't understand what you meant at all. If they leaked from waterjacket to waterjacket (meaning between the coolant passages) you wouldn't be overheating. This isn't very feasible since the coolant is only pressurized to 14-17 psi.

If they leaked from the cylinder to the waterjacket, you would be putting air into the cooling system (supposed to be a closed system) which will obviously create air pockets. This motor, as you mentioned, is known for blowing original head gaskets. However, if you got the coolant sniffed for hydrocarbons you'd probably find some (should have NONE). Also, just because you can't see any oil in the coolant doesn't mean there aren't trace amounts in it.

Most people go with head gasket problems for a while before the car ever overheats, from my knowledge at least.

Maybe I just misread it, or you can explain what you meant.

Thanks
Aaron
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Old 07-10-2008, 05:22 PM   #18
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Quote:
Originally Posted by chevynut View Post
One thing I had to do to get the bolts holding the drive plate to the flywheel. I unbolted the intake manifold bolts and then lifted it enough so i could get a long extension straight from the front. I couldn't get the bolts off the the access port.
With mine, I just used a flare-end wrench to break the bolts loose. After they were loose I used my fingers to get them out. They should be VERY easy to pull out. Just my 2 cents.
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Old 07-10-2008, 09:55 PM   #19
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Quote:
Originally Posted by fastenova View Post
I don't understand what you meant at all. If they leaked from waterjacket to waterjacket (meaning between the coolant passages) you wouldn't be overheating. This isn't very feasible since the coolant is only pressurized to 14-17 psi.

If they leaked from the cylinder to the waterjacket, you would be putting air into the cooling system (supposed to be a closed system) which will obviously create air pockets. This motor, as you mentioned, is known for blowing original head gaskets. However, if you got the coolant sniffed for hydrocarbons you'd probably find some (should have NONE). Also, just because you can't see any oil in the coolant doesn't mean there aren't trace amounts in it.

Most people go with head gasket problems for a while before the car ever overheats, from my knowledge at least.

Maybe I just misread it, or you can explain what you meant.

Thanks
Aaron

To be toally honest i wasnt quite sure what this "leaking tru the waterjacket" meant. I was told this from the local subie dealership.

My understanding was that you would see coolant in the oil and that was a heakgasket failure cause i had that happen on my 97 1.8 Impreza brighton.


My bad....
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Old 07-11-2008, 06:52 AM   #20
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Quote:
Originally Posted by SubieFan98 View Post
To be toally honest i wasnt quite sure what this "leaking tru the waterjacket" meant. I was told this from the local subie dealership.

My understanding was that you would see coolant in the oil and that was a heakgasket failure cause i had that happen on my 97 1.8 Impreza brighton.


My bad....
In my Subaru experience coolant in the oil was from intake manifold gaskets... coolant being sucked into the intake! Yeah, head gaskets CAN fail on any car. They're just extremely likely to fail on the DOHC 2.5L motors with the first rev. of the gaskets. More likely with this problem you see oil in the coolant and weird heating issues.

I remember the first time mine did it... Oh so long ago... I was driving with the heat cranked up and all of a sudden, the heat went away. It was like 30 degrees outside, but the air wasn't that cold. And it wasn't hot. I was so confused. Now I know that after a cooling system purge, it's likely to be head gaskets on a 2.5.

Good luck with the head gasket job. If you're going to do it yourself it's not too bad, and can be done for about $600 if you do all the right seals including the few "special" tools you need. Look around here or feel free to ask me if you need any information.

Aaron
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Old 07-11-2008, 09:34 AM   #21
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Quote:
Originally Posted by fastenova View Post
In my Subaru experience coolant in the oil was from intake manifold gaskets... coolant being sucked into the intake! Yeah, head gaskets CAN fail on any car. They're just extremely likely to fail on the DOHC 2.5L motors with the first rev. of the gaskets. More likely with this problem you see oil in the coolant and weird heating issues.

I remember the first time mine did it... Oh so long ago... I was driving with the heat cranked up and all of a sudden, the heat went away. It was like 30 degrees outside, but the air wasn't that cold. And it wasn't hot. I was so confused. Now I know that after a cooling system purge, it's likely to be head gaskets on a 2.5.

Good luck with the head gasket job. If you're going to do it yourself it's not too bad, and can be done for about $600 if you do all the right seals including the few "special" tools you need. Look around here or feel free to ask me if you need any information.

Aaron

man $600 bucks? Holy S**T the local subie dealership wanted just 1200 in labour plus another 300 for the gasket kit.

However the guy i bought it off of is the sales mang. at another subaru dealer and we are splitting on the labour costs and I am getting the gaskets at shop price.

Think its gonna be somewhere close to a grand....ouch
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Old 07-16-2008, 04:26 PM   #22
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you can do your own head gasket job for $300 or less....
rs25.com has a decent set of DIY directions and lots of links to that end....
did mine just a few weeks ago. probably ended up costing about $200 and about 3 days of work
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Old 07-16-2008, 05:59 PM   #23
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Quote:
Originally Posted by SubieFan98 View Post
man $600 bucks? Holy S**T the local subie dealership wanted just 1200 in labour plus another 300 for the gasket kit.
Sorry, when I said $600 I meant if you do the timing belt, water pump, rear main seal, and have to buy some tools. That's why I said, "about $600 if you do all the right seals including the few "special" tools you need".

Yes, head gaskets, by themselves, are about $100. Head bolts are $80. Water pump (non-OE) is ~$60. Timing belt is $60. If you don't have the proper torque wrenches and socket for the head bolts there's some additional expense there.

I also did all the VC and cam/crank seals, oil separator plate, rear main seal, intake and exhaust gaskets, plugs, air filter, etc.

And then I paid for two sets of oil (one initially and again after ~500 miles) which is about $30 a pop for full synthetic, plus one filter, coolant, etc.

That doesn't include the machine shop labor (Usually around $100 to have the heads hot-tanked, pressure tested, and resurfaced) or a valve job/adjustment.

I'm pretty anal retentive about doing things "right" and it cost more, but I'll be damned if that motor leaked any oil when I was done with it!
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Old 07-17-2008, 02:28 AM   #24
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Quote:
Originally Posted by fastenova View Post
I don't understand what you meant at all. If they leaked from waterjacket to waterjacket (meaning between the coolant passages) you wouldn't be overheating. This isn't very feasible since the coolant is only pressurized to 14-17 psi.

If they leaked from the cylinder to the waterjacket, you would be putting air into the cooling system (supposed to be a closed system) which will obviously create air pockets. This motor, as you mentioned, is known for blowing original head gaskets. However, if you got the coolant sniffed for hydrocarbons you'd probably find some (should have NONE). Also, just because you can't see any oil in the coolant doesn't mean there aren't trace amounts in it.
from what im gathering, it means the headgasket was causing coolant to leak externally. depending on which jacket it was leaking from, it might only leak coolant until it drains below that point, or if it was situated low enough, it might be able to drain the block.
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Old 07-17-2008, 05:17 PM   #25
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i drove 2 years with a blown head gasket. Had to pull over every 20mins and poor the overflow tank back into the radiater.
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