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Thread: Overheating, need help with diagnosis.

  1. #1
    Join Date
    Jul 2018
    Location
    Columbus, OH USA
    Posts
    3
    My Cars
    2004 325ci, 2015 528ix

    Overheating, need help with diagnosis.

    I love my e46 and have done myself or had done all regular maintenance and the car has run great. Well this summer a weird issue has begun. the history goes back to the winter actually.

    1st thing that happened was my expansion tank next to the radiator sprang a leak. I watched from under the cAR AS IT WARMED UP THE TANK WOULD SWELL and a crack formed along a seam and began spraying coolant out. I replaced the tank with an aftermarket one from Amazon. Seemed to be ok but periodically I would smell coolant or see small drops here and there. Also I would have to add 8oz of coolant every few weeks so I knew it was going somewhere but couldn't pin it down. looking & looking I couldnt find the leak.

    months go by.

    Now it's summer, the temps began to swing up sometimes then back down. Tracked it to a bad fan clutch. i Replaced the fan clutch and since i was in there and the car is at 188Kmi. the water pump as well. All autozone stuff. Temps returned to normal. Had system leak tested, shop said no leaks. I'm thinking I'm golden.

    1 week later out of the blue the temps began to climb again, slowly. A pattern emerged. Upon cold start, the car runs and warms up to normal temp perfectly within 8 minutes. It will maintain the correct temperature perfectly dead center for about 30 minutes. Then it starts climbing. At first slowly then more & more. After about an hour only freeway speeds and no AC on will keep it cool. If you have to slow down or get stuck in traffic you have to turn on the heat to help cool it. That immediately, and i mean in about 20 seconds, drops it back to dead center normal again but only as long as you run the heat full blast. It gets even hotter eventually though, after 1.5 - 2 hours in traffic, even with the heat on, temps wont stay at normal and swings to the hot side but stays out of the red usually. It feels like its progressive too. slightly shorter times till overheat over time. It was 40 mins then 30 now its actually probably closer to 20 minutes before the first signs show up. Also it has begun to occasionally throw a check engine light. Snap-on scanner reports cylinder misfires. After a couple restarts and drives the light goes away.

    I replaced the thermostat back around 90K mi and cant remember if i've done it again since, so I was hoping that was all that is going on here. Reading the tea leaves of how it acts however, I'm beginning to fear it's a head gasket issue. Especially with the chk eng light coming on now. Has anyone had similar experiences and can advise what they did if anything to correct it?
    Last edited by Wallywhol; 07-11-2018 at 04:46 PM.

  2. #2
    Join Date
    Jul 2004
    Location
    Houston, TX
    Posts
    12,462
    My Cars
    36 Cylinders
    Tell us about how you bled the system each time it was opened.
    -Abel

    - E36 328is ~210-220whp: Lots of Mods.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg
    - 1999 S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 270hp/430ft-lbs
    - 2019 M2 Competition, self-tuned, 504whp
    - 2016 Mini Cooper S

  3. #3
    Join Date
    Jul 2018
    Location
    Columbus, OH USA
    Posts
    3
    My Cars
    2004 325ci, 2015 528ix
    I filled at the bottle and let coolant flow to the radiator until the bottle was full to the stop mark. started the car with the bottle open. as the level went down I added until it wasn't dropping anymore. Still with bottle open, I opened the little plastic bleeder valve just right of the bottle on the hose joint. Just 2-3 turns, not all the way out. A small amount of air then just coolant came out. Closed bleeder. I put a little more coolant in the bottle till it began to flow thru the recirculator and a thin stream of coolant began to squirt from the holes near the top of the bottles neck back down into the bottle. Any air bubbles left could be seen as the stream would occasionally sputter and spit bubbles. Once the stream looked smooth and clear of bubbles and the car was up to temp I screwed back on the cap of the reservoir bottle and called it a day.
    Last edited by Wallywhol; 07-11-2018 at 04:20 PM.

  4. #4
    Join Date
    Dec 2013
    Location
    Chicagoland area
    Posts
    4,372
    My Cars
    EXOTICS
    Don't call it a day, it's not over yet!
    Every morning-cold engine-remove reservoir cap,
    then top off coolant to proper level-replace cap.
    Do this until top off not required.

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