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  1. #1
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    Bekasi, , Indonesia
    Member No: 167585 ETobing is an unknown quantity at this point ETobing's Avatar
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    Bleeding Screw-No coolant

    Hi guys, if it's not too late I would like to wish you all Merry Christmas and Happy New Year 2011!

    So on the way home from church last Christmas I shifted to Sport Mode and went at 140 km/h for about 2 minutes to recheck if the car's cooling system is perfectly fine. When reached home, with engine still running & temp needle was at the middle, I slowly turned the bleed screw and there was no coolant or bubbles came out. Nothing. Next morning I drive the car for a short trip everything looks fine. Is it normal no bubbles/coolant/pressure released after driving with S mode? Or does the thermostat fail to open? Appreciate your comment on this.

    Enrico Tobing

    528i E39 1997
    Automatic ZF 5HP18

  2. #2
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    Ooltewah, TN, United States
    Member No: 119706 Bmw540san is on a distinguished road Bmw540san's Avatar
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    Have you turned screw enough to release the

    pressure/coolant. Actually, you really shouldn't be doing that like that as it can spray hot coolant all over. You only do it a inital fill to purge the air.

    1998 BMW 540i 6 speed
    Arctic silver, M sport suspension (euro delivery), prod. date 05/98, non VANOS
    Staggered 18" style 32 OEM wheels
    3.15 open differential
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    AFE CAI with improved heat shield
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    AEA DRL module (aftermarket daytime running lights)

    1997 BMW 528iA
    Alpine white, premium package, prod. date 04/97, single VANOS
    Staggered 17" style 32 OEM wheels
    AEA DRL module
    Custom made sun blinds for rear seating area

    2000 Nissan Frontier Desert Runner, AKA "The Work Horse"

    Garage aids:
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  3. #3
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    Member No: jimcash's Avatar

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    Re: Bleeding Screw-No coolant

    Under those conditions you "should" be getting coolant come out the bleed screw - assuming the system is full and has been properly bled.

    With regard to the other message - it is very important to be careful when doing this. I always put a rag/towel around the screw area and open slowly with a long screwdriver so that any steam or coolant is somewhat held in check by the rag.

    Did you check that the coolant level was correct when the engine was cold? If so then you should try the bleed process again and keep the screw open until you do get some coolant. Then top up again and repeat (may have to do several times) until you get liquid as soon as you open the screw.

    Make sure you follow the full bleed process - posted on this forum many times.

    Be careful with the screw when tightening. Do not over tighten or it can crack the thread area - just make it snug so the coolant stops to flow.
    Actually a good idea to have a spare bleed screw.

    Jim Cash

  4. #4
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    Member No: Eurodavid's Avatar

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    Re: Bleeding Screw-No coolant

    Hi Enrico,

    Happy Holidays to you too!

    Along with the others said, know these things:

    There has to be coolant in some form coming out of the bleed screws. The bleed screw on our cars (mine is the exact same engine, year and make--automatic--of your car) will exhibit two slightly different characteristics:

    a) the bleed screw on the thermostat housing itself will, when the engine is very warm and/or especially hot, the fluid will not be a pretty (green or blue, depending on what you use) constant, gentle flow of coolant coming out. It will sometimes come out in what appears for a microsecond as a gel-foam (and you will hear no air hissing), but will appear as a water-foam that is weird in that it lacks bubbles but in reality is only pressurized rad fluid flying through the system. All this is is the coolant under a bit of pressure, but when you actually check it close, it is pure coolant, it just looks a little different when the engine is raging hot. But, that said, if there is air coming out, and/or if there is a void, you've got a big air pocket in the system, and you need to do Jim Cash's bleed procedures religiously. Also do what JimLev talks about (when the car is cold, take that bleed screw on the thermostat housing completely out, along with the rad cap off & the other bleed screw loose, get a funnel that fits into that housing bleed screw hole, and fill the system that way while watching the fill line on the expansion tank. Then put the rad cap back on, tighten the other bleed screw, and then bleed the system with this screw on the thermostat housing). I'll say it again: do Jim Cash's procedure a few times. It truly helps our I6s (especially if you have the radiator with the combined expansion tank) if you put the front of the car up on car ramps, then put a hydraulic jack under the center engine jack pad, designed specifically for lifting the car, and raise that jack until it's at its limit (the car will come off the car ramps).

    b) then, only "after" doing this with the first bleed screw, do you ever fool with the second bleed screw. The difference with the second bleed screw is that no matter if the engine is dead cold and/or screaming hot, when you loosen that second bleed screw, a beautiful, pure stream of your rad fluid will flow out and it will look nothing like the stuff that comes out of the first bleed screw if you are doing the second part of Jim Cash's bleed procedure and the engine is hot (best do it only when it is warm, though).

    Also, here is a hint about when using that bleed screw on thermostat housing to start the bleeding process. I've personally found that rags and papertowels or whatever are messy, are tough to place & hold when the engine fan is whirring 2 cms away from your fingers. They simply do not stop all the fluid that will come out of that screw from reaching the pulleys and/or belt below. There is a trick for "zero" amounts of fluid reaching there, though. How? Get your typical wet/dry shop vacuum you have around the house and/or in the garage, put it on it's "wet" setting, put the slim opening nozzle on the vacuum hose, then turn the vacuum on, put the nozzle right beside the bleed screw (almost creating a full suction grip), and then beginning slowly bleeding that screw. That vacuum will suck up any and everything that comes out of the bleed screw, as the circular vortex is too powerful around the circular bleed screw for any fluid to go anywhere except straight into the vacuum nozzle. It works excellent (just have to rinse your vacuum out, which is no trouble). You can bleed to your heart's desire, with full control of a large blade screwdriver in one hand, and the vacuum nozzle in the other.

    Just as an opinion, I've got a bad feeling, Enrico, that from reading your posts over the past months about this "air in the rad system" problem and other cooling problems you seem to have had and/or are having, that somehow, on one of the repairs that was made to the rad system, it was not repaired properly (bad hose, bad hose fit, loose clamp(s), thermostat housing slightly loose, a stripped bleed screw, a radiator that is slowly leaking, even if it is new, a bad head gasket, or something) that is allowing air to get into the cooling system when the engine gets hot and components expand. Then when they contract overnight, the system seals, and that little bit of air is stuck in there, waiting to be joined by another bit of air when you go for your next drive. . Eventually, after some days of this, you've got a problem again.

    Hope I am wrong about this. I would have hoped you already had removed the thermostat, tested it in a pan of boiling water to see if opens correctly, and at the least replaced the gaskets and seals involved with the housing and thermostat, to rule these simple things out.


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