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Thread: Radiator Hose pops off

  1. #1
    Join Date
    Aug 2013
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    Radiator Hose pops off

    This may have a simple answer, but if so; i haven't found it yet, so here goes.
    While driving my 2000 z3 recently the top radiator hose popped off the radiator. The clamp was still on the hose but the hose was not connected to the radiator. Obviously all of the coolant gushed out, luckily i was able to make it to a gas-station before it overheated.
    I was able to re-attach the hose; tighten the clamp down, refill and bleed the reservoir. It ran fine again for several days; then did the same thing; upper hose popped off.
    This has happened three times now, I am uncertain as to where to start. The hose seems intact and fits on snugly, the clamp seems to be tightening down; although i don't know the spec for this.
    Any suggestions?

  2. #2
    Join Date
    Jul 2004
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    Is the radiator spout intact?
    -Abel

    - E36 328is ~210-220whp: Lots of Mods. RomRaider self-tune work in progress.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg: Many Mods ~300ft/lbs tq, diesel, daily beater. Love/Hate relationship.
    - S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 250hp/400ft-lbs

  3. #3
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    Aug 2013
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    Yes, as best as i can tell it doesn't appear to have any damage. Logically, im guessing either the hose/clamp won't hold under normal pressure, or I'm generating more pressure than normal. Not sure how to go about figuring that one out.

  4. #4
    Join Date
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    Check inside the hose and see if part of the neck broke off. I once had issue and neck looked ok, until I realized that a perfect 1/2" of the neck broke off and was in the hose.
    Current Cars
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  5. #5
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    Quote Originally Posted by bagekko View Post
    Check inside the hose and see if part of the neck broke off. I once had issue and neck looked ok, until I realized that a perfect 1/2" of the neck broke off and was in the hose.
    Aaand that's the word that wasn't coming to mind.

    Most likely the neck is broken ---> new radiator. They make full aluminum ones that last for life.
    -Abel

    - E36 328is ~210-220whp: Lots of Mods. RomRaider self-tune work in progress.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg: Many Mods ~300ft/lbs tq, diesel, daily beater. Love/Hate relationship.
    - S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 250hp/400ft-lbs

  6. #6
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    Feb 2002
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    Quote Originally Posted by 328 Power 04 View Post
    Aaand that's the word that wasn't coming to mind.

    Most likely the neck is broken ---> new radiator. They make full aluminum ones that last for life.
    This.
    Even if it isn't fully "broken" yet, the neck may have cracked to the point that it won't hold a hose clamp.

  7. #7
    Join Date
    Jun 2011
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    Springfield, Ohio, USA
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    1998 Z3 Roadster
    A couple of things come to mind. A blown head gasket can cause this by allowing combustion pressure into the coolant system. Let's hope that's not your problem.

    I'm also worried about this: "...luckily I was able to make it to a gas-station before it overheated." Aluminum engines tolerate almost no additional operation once coolant is lost. Many of these engines have been destroyed by attempting this. Let's hope yours is not one of them.

  8. #8
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    Quote Originally Posted by Blacklane View Post
    A couple of things come to mind. A blown head gasket can cause this by allowing combustion pressure into the coolant system. Let's hope that's not your problem.

    I'm also worried about this: "...luckily I was able to make it to a gas-station before it overheated." Aluminum engines tolerate almost no additional operation once coolant is lost. Many of these engines have been destroyed by attempting this. Let's hope yours is not one of them.
    That is a good point too. I've seen a blown headgasket X3 2.5 shoot water 5+ feet in the air from the expansion tank as I was *trying* to bleed it after a new thermostat/wp (which didn't fix the overheating). Exhaust gases making it into the coolant system while revving it a little, to get the coolant moving.
    -Abel

    - E36 328is ~210-220whp: Lots of Mods. RomRaider self-tune work in progress.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg: Many Mods ~300ft/lbs tq, diesel, daily beater. Love/Hate relationship.
    - S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 250hp/400ft-lbs

  9. #9
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    Thank you all for the advice. I'll check the radiator neck for damage and go from there. Last two times is popped off the engine was revving about 3000 rpm. The blown head gasket theory certainly sounds plausible. Assuming i have to tear into her to replace the head gasket, and assuming the block isnt warped from the initial pop-off, what else should i plan to do while i'm at it?

  10. #10
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    Quote Originally Posted by MGilsinger View Post
    Thank you all for the advice. I'll check the radiator neck for damage and go from there. Last two times is popped off the engine was revving about 3000 rpm. The blown head gasket theory certainly sounds plausible. Assuming i have to tear into her to replace the head gasket, and assuming the block isnt warped from the initial pop-off, what else should i plan to do while i'm at it?
    The broken neck prognosis is valid, the ridge that keeps the hose on would be on the broken section, combustion pressure in the cooling system should pop the expansion tank cap valve first, at 15 psi.Good luck on a broken rad. outlet, very likely.

  11. #11
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    I'd check the "neck" as well. I had it happen to me and I didn't see it at first. It's what made me overhaul my cooling system. The same thing happened to me while I was pulling out of a parking lot. I ended up clamping the hose all the way at the tip in order to hold and not put any pressure on the neck itself.

  12. #12
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    Broken neck would be preferable to head gasket.

  13. #13
    Join Date
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    As mentioned earlier, check that your hose neck on the radiator has the ridge intact at the end which gives the hose/clamp something to grip on.
    If thats ridge is intact, are you running (stock type) black rubber hoses? I have seen aftermarket silicone hoses (usually blue in color) that simply won't stay connected to the neck, no matter how tight the clamp is.
    -Donny

  14. #14
    Join Date
    Aug 2013
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    29
    Update
    I pulled the upper hose off the radiator and inspected the neck. At first glance it is fully intact.
    Feeling the radiator hose I noticed something 'hard' inside it. I dumped it out and removed to semi-circular pieces of plastic.
    Needless to say it looks like the last 1/8 inch of the neck split off the radiator in a perfect circle.
    This portion is wider in diameter than the remaining neck and I'm assuming was what kept the hose in place when clamped on.
    I've temporarily relocated the clamp closer to the radiator; until I can buy a new one.
    Thanks all for the advice.
    Next question, where is a good replacement available from?

  15. #15
    Join Date
    May 2012
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    2000 BMW Z3 2.3 Auto
    I had the same issue. Hose popped off two times. Bought a replacement radiator from a local guy with life time warranty (not a wise decision, but had to do it - ~$160). Months passed and no issue at all. I have exact same car, 2000 2.3 with 119K on it.

    Good luck.

  16. #16
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    Quote Originally Posted by MGilsinger View Post
    Update
    I pulled the upper hose off the radiator and inspected the neck. At first glance it is fully intact.
    Feeling the radiator hose I noticed something 'hard' inside it. I dumped it out and removed to semi-circular pieces of plastic.
    Needless to say it looks like the last 1/8 inch of the neck split off the radiator in a perfect circle.
    This portion is wider in diameter than the remaining neck and I'm assuming was what kept the hose in place when clamped on.
    I've temporarily relocated the clamp closer to the radiator; until I can buy a new one.
    Thanks all for the advice.
    Next question, where is a good replacement available from?
    If you're looking for basic value (but you do get what you pay for) look at www.Rockauto.com (more specific https://www.rockauto.com/catalog/x,c...oling%2BSystem ) , they have some options, including a radiator for $132 +~$10 shipping.
    -Abel

    - E36 328is ~210-220whp: Lots of Mods. RomRaider self-tune work in progress.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg: Many Mods ~300ft/lbs tq, diesel, daily beater. Love/Hate relationship.
    - S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 250hp/400ft-lbs

  17. #17
    Join Date
    Aug 2013
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    29
    Thank you for the validation; glad to hear i am not the only one who has experienced this. When you say 'local guy' any suggestions where i might start my search. I live in Arkansas, so not a lot here locally that i am aware of.

  18. #18
    Join Date
    Mar 2011
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    '01 F-250 Diesel
    This is what mine looked like when the hose popped off... if this is what happened... radiator should be replaced.



    1993 E36 325i (RIP)
    1995 E36 325i (SOLD)
    1987 E30 325i (SOLD)
    1990 E34 535i (SOLD)
    2001 Z3 2.5i Roady (SOLD)
    2001 Z3 3.0i Coupe (SOLD)
    1997 E36 328IC (SOLD)

  19. #19
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    Definitely the neck. Happened to me as well.
    1999 528i - Titanium Silver over Silverstone/Black Leather, Sport
    2000 Z3 2.3 -Topaz Blue over Sand Beige, Sport
    2003 M5 - Imola Red over Imola Red/Black, Sport
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