Very very strange cooling system issue .. Help please!!
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This is a discussion on Very very strange cooling system issue .. Help please!! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Hi ... I own a classic GC8 Impreza WRX and since around 1 month I have noticed the following: - ...

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    Exclamation Very very strange cooling system issue .. Help please!!

    Hi ...

    I own a classic GC8 Impreza WRX and since around 1 month I have noticed the following:
    - radiator fan is always on when the engine is at normal operating temperature
    - the radiator it self is hot on the left side but ice cold on the right side
    - the car does NOT overheat!!! (which is very strange)
    - the coolant level does NOT drop at all
    - the engine power and turbo boost are fine and unchanged
    - there is no trace of oil in the coolant (or coolant in the oil)
    - and very recently I started to hear a funny running water noise when i go around corners!

    I have been to several workshops to try and fix this but no luck so far, what I have done so far is:
    - replaced the thermostat twice (original parts from the Subaru dealer)
    - completely drained the coolant from the radiator and the engine, this was done twice
    - bleeded the cooling system 3 or 4 times

    The really weird thing is that is that after each time I replace the thermostat or drain the coolant the car works perfectly (water circulates normally in the radiator) for 1 or 2 days then it goes crazy again (same symptoms described above)

    My mechanic insists that it is a problem with engine head saying that it is leaking water out and he wants to take the engine apart to inspect it!!!

    I really appreciate your help guys, I really don't want to take my engine apart when I'm sure there is nothing wrong with it

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    Registered User teflon_jones's Avatar
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    Sounds like your cooling system has junk in it. I'd guess maybe the radiator is clogged.
    Scott
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    Registered User oguitar's Avatar
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    ^^ I agree.

    Might have to take the radiator itself off and see if water flows through it.
    Life is like riding a bicycle in order to keep your balance you must keep moving.

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    He simply abides. SD_GR's Avatar
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    What is the problem?

    The car doesn't overheat. You can't make it not overheat less.

    Is the fan the problem? Is there a CEL on?

    I'm not clear what you're trying to address here.
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    Moderator T0rque's Avatar
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    Sounds like it's acting normal to me, besides the radiator being that extreme difference... One side of the radiator will be cooler than the other because the longer the water stays in the radiator the colder it gets from the air.. But that extreme sounds like you either are beginning to loose your water pump or your radiator has some clogged cores


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    Basically the problem is that the water doesn't seem to circulate fully in the radiator and the engine, Once the engine hits normal operating temperature the fan comes on and never goes off, the other thing is that the radiator is hot on the left side but ice cold on the right side, ideally both sides of the radiator should heat up (the left being hotter) as the water circulates through the radiator.

    Whats driving me crazy is that after I replaced the thermostat and drained the radiator a few days ago everything was fine, the fan came on and off as needed and the whole radiator heated up, but this only lasted for 2 days before it went crazy again!

    I just finished bleeding the cooling system and managed to get some air bubbles out but the problem is still there... however I noticed there is some junk and traces of a "radiator stop leak product" in the coolant, I used the stop-leak thing around 2 years ago to stop a leak in my old radiator but since then I have replaced that radiator and flushed the coolant several times.

    By the way I checked again and thankfully there is no oil in the coolant.

    What do you think guys, any ideas? is it a clog somewhere?

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    Exclamation

    I'm following up on my earlier post in the hope that someone will benefit from this ...

    I'm still struggling with the problem reported earlier, and I have tried everything from bleeding the air out of the cooling system to replacing the thermostat several times, the end conclusion that I have reached is what my mechanic has been saying all along, it seems there is a small leak in the head gasket and somehow this leak is stopping the water from circulating in the cooling system!

    Now to fix the problem permanently I have to take the engine apart and replace the head gaskets which is a rather expensive job and I don't really wanna go down that path, as a work around my mechanic has taken out the thermostat and removed the spring and valve from it and then reinstalled the thermostat, basically the thermostat is now always open and water circulates freely now in the system, my mechanic claims that he has done this on so many STi's and its the best thing that you can do if you don't want to replace the gasket.

    I've been driving the car with the above mentioned workaround for 2 weeks now, and the only issue I have noticed is that it takes longer for the engine to warm up and if you drive down long hills without loading the engine (selecting a lower gear) the engine temp tends to drop a little bit, other than that everything seems to be working perfectly.

    Good luck to everyone thats been suffering with this issue! ... if you have ideas or bad experiences related to this topic please feel free to share them.

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    He simply abides. SD_GR's Avatar
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    I'm still trying to understand this.

    If you are not losing coolant (you emphasized NOT) in your post above, what is the nature of the head gasket leak? Are gases entering the coolant instead?
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    Registered User jd92677's Avatar
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    It doesn't make sense to me that a head gasket leak is preventing coolant from flowing and removing the thermostat is temporarily solving the problem. A blown head gasket usually does 1 of 2 things... mixes oil and water or injects exhaust gases into the cooling system. You've already stated that there is no oil in the coolant so have you checked for hydrocarbons in the cooling system? Could it be a faulty thermostat (just because it's new doesn't mean its good)? But after reading the thread through I'm not really sure what your concern is. The car doesn't overheat, no oil in coolant, what makes you think that the coolant isn't flowing?

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    This Hydrocarbons in the coolant theory seems interesting, can you guys tell me how to check for that?.. by the way each time I bleed the system I noticed some air bubbles coming out and then the cooling system would work perfectly, the next day though it goes crazy again! could these be exhaust gases coming out!!??

    I've also been checking the coolant level each morning over the past two weeks (after the thermostat was removed) in both the head tank and the overflow tank and there doesn't seem to be any drop in the water level!

    By the way, yesterday I tested the last thermostat I had on the car by putting it in boiling water and it did open up, so I guess that means its working

    jd92677 .. I really wish the car would overheat then I would know for fact that gasket is the issue but it never did, if I hadn't noticed that the fan is always on and the right hand side of the radiator is always cold then I would never have known I had a problem!

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    Registered User jd92677's Avatar
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    Quote Originally Posted by x_miles View Post
    This Hydrocarbons in the coolant theory seems interesting, can you guys tell me how to check for that?.. by the way each time I bleed the system I noticed some air bubbles coming out and then the cooling system would work perfectly, the next day though it goes crazy again! could these be exhaust gases coming out!!??

    I've also been checking the coolant level each morning over the past two weeks (after the thermostat was removed) in both the head tank and the overflow tank and there doesn't seem to be any drop in the water level!

    By the way, yesterday I tested the last thermostat I had on the car by putting it in boiling water and it did open up, so I guess that means its working

    jd92677 .. I really wish the car would overheat then I would know for fact that gasket is the issue but it never did, if I hadn't noticed that the fan is always on and the right hand side of the radiator is always cold then I would never have known I had a problem!
    The easiest way to test for HC in the cooling system is to get (or borrow) a block tester. It's basically a 2 chamber syringe that you put fluid into, place it over the open radiator cap, and suck gases from the radiator. If there ar HCs in the system, the fluid changes color. I'm not understanding why you think there is a problem though. Are you only worried that the fans stay on? If the car runs fine and there are no leaks, no overheating, why are you looking for a problem. If there was no flow, you would overheat within a few minutes. Do the fans always run from the time you start the car cold? Maybe you don't have a cooling system problem, maybe its a coolant temp sensor causing the fans to stay running.

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    Registered User teflon_jones's Avatar
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    Quote Originally Posted by x_miles View Post
    I just finished bleeding the cooling system and managed to get some air bubbles out but the problem is still there... however I noticed there is some junk and traces of a "radiator stop leak product" in the coolant, I used the stop-leak thing around 2 years ago to stop a leak in my old radiator but since then I have replaced that radiator and flushed the coolant several times.
    I stand by my original post. Your radiator is clogged.

    You flush the system and it goes away because the junk is moving around when you drain it and probably settling. After a couple of days of running the car, the junk is moved around by the coolant flow and clogs things back up.
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
    '13 Wrangler Rubicon - custom front bumper w/12k lb winch & off-road lights, skid plates, diff guards, etc.
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    Moderator T0rque's Avatar
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    Quote Originally Posted by teflon_jones View Post
    I stand by my original post. Your radiator is clogged.

    You flush the system and it goes away because the junk is moving around when you drain it and probably settling. After a couple of days of running the car, the junk is moved around by the coolant flow and clogs things back up.
    Same thing I said..


    Lead Wrench @ WTF Tuning, LLC

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    Registered User teflon_jones's Avatar
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    Quote Originally Posted by T0rque View Post
    Same thing I said..
    Uh huh I saw that and was going to quote it but I got lazy.

    I think the OP should just listen to you and me and ignore all other opinions since we're right.
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
    '13 Wrangler Rubicon - custom front bumper w/12k lb winch & off-road lights, skid plates, diff guards, etc.
    '04 Porsche 911 Turbo GT2 clone 600 HP/TQ
    '77 F-150 heavily modded for off-roading

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    Thank you all for your help ...

    I finally managed to find a block tester and tested for Hydrocarbon traces in the cooling system... thank God there were none LOL .. Ok now I'm glad but totally lost!

    My plan now is to re-install the last thermostat I had but after I remove the small air valve thats on it to try and keep a bit of flow going all the time ... in the meanwhile I will order a new thermostat from a different country to try and avoid the whole batch from which this one came.

    Another idea is to try and pressurize the whole cooling system and test for leaks...

    Any better ideas guys?

    Note to jd92677: I'm sure the temp sensor is fine since the fans now come on and off normally (that is on warm days), could a failing water pump cause issues like what I'm having?

    Note1: running the car with no thermostat turned out to be a very bad idea especially when the weather got colder, now its almost impossible to get the engine to maintain its heat while driving and also the car is consuming gas like crazy!

    Note2: regarding the clogged radiator theory, I don't think its valid simply because the coolant circulates perfectly now in the whole system (without the thermostat)

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