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Thread: FU on “HowTo -> Engine Cooling system: Replacing coolant vent hose on V12”

  1. #1
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    FU on “HowTo -> Engine Cooling system: Replacing coolant vent hose on V12”

    Tried to do this on the HowTo thread but the thread has been locked by the Moderator... after 11 years, why not? Maybe if this info is good enough it could get added there?


    So I too had the Y-pipe failure and needed to replace it. Great write-up in the following thread on how to do it without removing the intake and everything else. Many thanks to OP. My notes below.

    https://www.bimmerforums.com/forum/s...nt-hose-on-V12

    1. I only replaced the Y-pipe. Daily driver so needed it for tomorrow.
    2. I did not remove anything other than the fan clutch, thermostat electrical connection, and the electrical connection to the injector. This might have cost more time but overall successful.
    3. Total time for me
    Start: 1300
    End: 2200
    But that includes 60 mins figuring out what is actually meant in the thread (sorry, original pics kinda suck), 65 mins at kids TKD practice, 75 mins dinner and kids bedtimes, 30 mins continuously chasing dogs away from coolant, 30 mins walking said dogs, and 45 mins explaining to wife/neighbors/etc what I was doing. So total actual time was probably 4 hrs from first action to end action (system bleeding).
    4. My pictures to add:
    This is the hex-driven screw you are going for as visible from injector 1

    This is what it looks like from the top and between the heater pipes when you have the hex seated


    5. I used magicfingers (and didn’t need a replacement screw) but if you don’t at least have the magnetic tool don’t even think about this.
    6. OP wasn’t kidding when saying patience to take it out is trying; patience going in... I had to take at least five frustration breaks putting that damn screw in and almost said f-it, it probably doesn’t need the screw twice. If you are impatient, stop and do not proceed.

    Again, thanks to the OP for the thread!


    2001 750iL DD74441
    Stock

    RIP: 2003 540iA Sport GS56111
    H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

  2. #2
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    Damn you actually did it with success. I look at it, I stared at it, look at it again, and I decided I do not have the patience, or even remote possible even with patience. To put it into proapective, literally 1 bolt and took 4 hours, that's alot of patience! Kudos more power to you!

    Sent from my VS995 using Tapatalk

  3. #3
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    Quote Originally Posted by asianvenom View Post
    Damn you actually did it with success. I look at it, I stared at it, look at it again, and I decided I do not have the patience, or even remote possible even with patience. To put it into proapective, literally 1 bolt and took 4 hours, that's alot of patience! Kudos more power to you!

    Sent from my VS995 using Tapatalk
    Thank you and lol! Yes, when putting it that way... is it patience or “I’d do anything not to have to pay someone” or better yet: “Dear god, let me finish so my wife won’t belittle me as I have to tow and pay someone else to finish”.


    2001 750iL DD74441
    Stock

    RIP: 2003 540iA Sport GS56111
    H&R front springs, Ultimate Cup Holder, Euro Dash & Armrest, Grom, BavSound Stage1

  4. #4
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    Thanks for describing your journey! I have a bit different situation on hand. I did a lot of maintenance work on the car, engine bay, suspension and currently experiencing an overheating of some sort while idle. I took a decision to review the whole thing thoroughly including changing the water pump (thermostat was replaced before). And yes - that crank bolt was a tough one. I don't think I have found anything crimical-like after I have removed the pump, except while it rotates it has somewhat squeaky note to it. But a more interesting find was that cooling vent hose instead of being a Y type, is short, straight and leads directly to radiator hose extension. In your writeup and photos the focus is on the barely reachable nut, but it's not entirely clear if the actual hose is supposed to be plugged somewhere, or all it is supposed to do is provide the means to vent? What kind of direct negative impact such hack (as described above) would have? Impossible to vent the system, overheating?

  5. #5
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    Not sure - but it should split and go to the radiator end tank on the left side of the car as well. What you have seems like a ‘fix’ done later. I would get the right hose - or make a hose with a T fitting. The left end tank should have an elbow fitting. Do you see one?

  6. #6
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    This is also for the TU, so pre-99(?) wouldn’t/shouldn’t have this.

    As for purpose, it may serve to
    1) heat everything up faster
    2) allow venting for bleeding
    3) serve as additional trigger to the thermostat

    Maybe these will help decipher?

    https://ia801005.us.archive.org/11/i...%20Systems.pdf

    https://bimmercat.com/bmw/en/search/...3N/USA/11_2301


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  7. #7
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    Quote Originally Posted by TheAngryBear View Post
    This is also for the TU, so pre-99(?) wouldn’t/shouldn’t have this.

    As for purpose, it may serve to
    1) heat everything up faster
    2) allow venting for bleeding
    3) serve as additional trigger to the thermostat

    Maybe these will help decipher?

    https://ia801005.us.archive.org/11/i...%20Systems.pdf

    https://bimmercat.com/bmw/en/search/...3N/USA/11_2301


    Sent from my iPhone using Tapatalk
    Neat links! Thanks!

  8. #8
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    Thank you for all the links and explanations. Currently, I'm mostly concerned that something was done to the valley pan in order to plug the hole and I'm aware I might be asking the most obvious question here, but I made a sketch of how I understand that part of the hose plugs into the whole thing. Have in mind I'm having a hard time navigating since my hose was completely stripped, I was convinced this was the correct hose, but because of the maintenance routine and somewhat worn look I have decided to replace it and to my surprise discovered it's not what it's supposed to be. I will not be able to work on a car for several weeks, for the time being I have just ordered all the parts including the correct hose, but would like to prepare myself mentally for the challenge

    https://ibb.co/W6pq5NB

  9. #9
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    So I finally got to work on the car. To my surprise, I have a pre-TU version of a valley pan - meaning no holes, neither for a hose nor for a nut. So I rolled my sleeves and went on to disassemble the whole thing, even though previously I swore I'm not taking intake manifolds ever again. Thankfully I didn't break any nuts and the whole thing looks like it was like this from the factory - all factory bolts, original gasket. Mine is the end of 99, the US version. Why would anyone change the valley pan in the first place and why would they use an incorrect part while they are at it? This leaves me very confused. I have asked the local dealer to clarify the situation, or at least offer a decent price on the correct valley pan. To make things worse, the older new part from the dealer is almost 5 times cheaper than the newer one, although they are practically identical

  10. #10
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    Interesting…

    So maybe a different thermostat/waterpump that didn’t have the connection point? You don’t happen to be a special market or individual?

    As for the price increase… it costs a lot to drill the hole???


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  11. #11
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    What is the VIN - if you don’t mind ( at least the last 7 digits )

  12. #12
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    It's not individual, the newly ordered water pump (by VIN) looks exactly the same as the one I removed. As for the hole drilling, in my mind, that's continuing on the hacking path besides the cover where the hole is supposed to be is rather thin, I don't think it will provide enough depth to properly seal (even if I nail the the width of it presicely) and also there won't be a enough material to drill the hole for the nut to hold that hose in place. The last 7 digits of my VIN - DD73942

  13. #13
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    Ha, I meant the additional cost for the part was because of the hole; not for you to drill it.


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  14. #14
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    I see it now BMW dealer couldn't explain it either when I challenged pricing logic, it was basically a shoulder shrug with "BMW sets the price the way they want and there's nothing we can do"

  15. #15
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    Haha - I have DD73956 - just down the line. Same day, or likely within a day. You have a M73TU for sure. You have a watercooled alternator, right?

  16. #16
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    Correct, water-cooled alternator. And yes, our cars likely stood close together at some point

  17. #17
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    So your car came to the US, but at some point made it back to Europe?

  18. #18
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    Yup, I bought it from US auction and went on the quest to restore it to its former glory. E38s are usually rather rusty here in Europe, so it's not a great start compared to some examples from warmer States.

  19. #19
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    Quick update on my endeavor. So the new valley pan finally arrived, thankfully none of the bolts were too stubborn and I replaced the entire assembly: most of the hoses, pump, and radiator (the thermostat was brand new already). Hooked everything up and since the last time bleeding the system was a source of huge pain and misunderstanding, decided to use a vacuum filling valve, worked well, although I can't reliably say that the vacuum would stay on the level for hours, at this point in time I decided that the valve itself is a bit leaky, including the cap adjustment, etc. So the system is filled to the right level and I haven't noticed any leaks on my garage floor. Obviously, the real test will be once it's running. But for now, I'm stuck with the intake manifold gaskets. Once I have assembled them, decided to use a smoke machine and verify it doesn't have leaks. Oh boy, I was naive, those old rather solid gaskets have developed some imperfections and cracks and a massive amount of smoke came from the back of the manifold. Assembling and disassembling intake manifold on this engine is not a fun activity, I got much better at it, but that is still far from pleasure

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