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Topic Review (Newest First)

  • 10-31-2010, 02:11 PM
    stukreit

    Yay! Not a blown head gasket!

    This was a happy ending. No head gasket! Its the coolant pipe under
    the intake manifold.

    I built up a leakdown tester but instead of testing cylinders I used it to apply continuous pressure to the
    cooling system. Also, I filled, burped, and refilled the cooling
    system to absolutely the maximum amount of water it could take.

    The output is a 1/8" NPT thread. It screws into the coolant tank
    bleeder pretty well. Its not an exact match but doesn't disable
    the thread, the bleeder can be reinstalled and holds fine. A janky
    approach, but coolant tanks are crap anyway and should be replaced
    regularly.

    This was all to maximize the observability of a leak. With the ability
    to dial the pressure up and down I was able to verify that the coolant
    fill cap was working.

    With spark plugs removed and continuous 20psi supply, the sound persisted but clearly was not coming from the cylinders. After removing the intake (an incredibly difficult job until you identify
    both of the bottom support brackets), the leak finally showed itself.

    Now to identify all the seals and hoses under there is hard to do. Between Realoem.com, pelicanparts.com, and autohausaz.com, all pieces are not clearly identifiable. I'll have to resort to talking to a live person to complete the order.
  • 10-31-2010, 12:31 PM
    Nedmon

    Re: Spray with soapy water and look for bubbles

    My recent experience with slowly increasing temperature is relevant.

    A few months ago I replaced the connection pipe, the one with the bleeder screw since I had broken the original with a poorly directed hammer blow as I unscrewed the fan nut.

    Pleasantly surprised with the metal replacement, an improvement on the plastic original, I installed it and began living happily ever after.

    Back to my slowly increasing temperature, I traced the cause, a coolant leak to the bleed screw on the new metal pipe. Even though the thread size is correct, it requires much more effort to tighten down the bleed screw and though it felt tight it was not compressing the O ring.

    Related, I replaced the water pump with a metal impeller unit by Graf. At 130,000 miles I decided why not. The original pump also has a stainless impeller and was fine.

    Ned
  • 10-30-2010, 07:02 PM
    BigRickMc50

    Re: Fearing a blown head gasket

    While the system is pressurized, use a 2'-3' long piece of vacuum tubing (like a stethoscope) to locate the hissing.

    Good Luck
  • 10-30-2010, 02:07 AM
    stukreit

    Fearing a blown head gasket

    Have water pump pulley off, a minor amount of leaking past the
    top rad/thermostat hose was closed with some water resistant grease,
    but it's still hissing pretty loudly and still uncovered. I have
    a simple diy leakdown tester and will wield it in the morning.
    Have done head gaskets on older bmws and others. Main problem on
    this one is that I don't have the special tools, esp the crank position
    locking pin and cam timing blocks. This will need special care.
  • 10-29-2010, 10:40 AM
    Enrico Tobing

    Re: I question your method of saying the head gasket(m

    I think you are probably right, with this overheating on and off for almost a year--sometimes red light turned on when I realise it--there's a chance the head gasket is failing.

    Frankly I haven't done pressure test myself and I doubt I can get the right tool here. We do have Ace Hardware here in Jakarta but not sure if they sell it. Anyway thanks for your valuable advice. Cheers!

    ET
    528i/E39/1997
  • 10-29-2010, 06:25 AM
    jimlev

    Spray with soapy water and look for bubbles






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  • 10-29-2010, 02:15 AM
    stukreit

    I'm hearing the leak but cannot pinpoint it

    I'm using air pressure of 20 to 22 psi on the overflow bottle and
    can hear air hissing out from somewhere in the front, but cannot
    locate it. I have the fan&shroud, and air filter/maf boot off.

    Am yanking on the thermostat, front hoses, etc, nothing seems to
    affect the leakage sound.

    There's a chance this is a head gasket, but I have no proof and the
    car runs great down the highway. Am trying to put together a leakdown
    tester from parts, but its surprisingly hard to find 1/4" and 1/8"
    bushings and fittings these days.
  • 10-28-2010, 12:46 PM
    edjack

    A failed head gasket can also introduce >>

    combustion gases into the coolant. There are test kits to detect this, also.
    Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.
  • 10-28-2010, 12:41 PM
    JimCash

    Re: Some answers (m)

    2 comments

    - the cooling system is "the total system". Just because you do not have a problem when cold does not mean you do not have air in the system. In fact I suspect you do. The "cold" part of the bleeding procedure is not related to cold operation, but rather it is how you can get air out of the heater part of the system. And air in that section is still "part of the system".

    - you can not say you have a "perfectly sealed" system unless you do a pressure test. Even then it can be difficult to detect and locate a minor leak. I had one several years ago that was an "iffy" connection on one of the heater hoses at the rear of the engine. It would only fail when the system was "hot". It was not leaking fluid but only vapour - because the way the hose was positioned there was a slight air pocket at that location so it was only steam that was escaping. Then as it cooled it pulled air back in at the same point - so it was a self perpetuation air pocket.

    The system passed a pressure test when cold, but not when hot.

    Another item about hoses and clamps - make sure you do not over tighten any of the clamps. It is more important to be sure that the hose and pipe (or connector) are clean and in good condition (inside of hose is most important) and then a clamp with normal tightness should hold it.

    JimLev is correct in that you should also be considering an internal engine issue - again a pressure test will help.

    Cheers
    Jim Cash
  • 10-28-2010, 08:35 AM
    jimlev

    I question your method of saying the head gasket(m

    is OK. Oil in the coolant is one way the head gasket is at fault, but you could also have a leak between the cylinder to a water jacket port.
    If you don't want to bring the car to the dealer to get a pressure check done why don't you purchase a pressure tester kit? It will probably cost less than what the dealer will charge for 2 hour of work, you can then sell it on eBay when you are done with it. (Eurodavid might need one)
    I think unless you do the pressure test you are not going to find your problem.
  • 10-28-2010, 06:20 AM
    ETobing

    Re: Some answers (m)

    Thank you Jimlev and Jimcash. I have checked it all and I believe there are no more leaks in the system. So far I have replaced radiator, thermostat and its housing, fan clutch, and the hose that goes from under the throttle body to engine block which was found leaking couple of months ago. The thermostat housing in particular have been replaced two times because the first change--using a non-OEM part--still leaking.

    The only thing you suggested that has not been done yet was to do pressure testing because such can only be performed at authorized dealer and I am a bit hesitate to go there.

    Failing head gasket in my opinion can be inspected by looking at the coolant in the radiator whether or not it is mixed with engine oil. In my case it is nothing like that I can safely put aside the possibility.

    I skipped Jimcash cold engine procedure since I don't have issue there; problem lies on hot procedure which I must admit hard to follow. Every time I open the bleed valve--while engine is still running--I could not get bubble-free coolant come out. If I must wait a little more I am sure I will empty the radiator. It become more confusing to see the upper and lower radiator hose shrinks few minutes AFTER shutting off engine.

    Even more frustrating to me is the fact that after driving the car at "S" or "M" mode coolant level mysteriously dropped. Now, considering that I have a perfectly sealed system why this happening? Why the system is able to maintain normal temp only with normal driving? Again I can only say never have this before with my late 520i 6-cylinders and definitely with 318i 4-cyl!

    ET
    528i/e39/1997

    Rgds,
    Enrico Tobing

    528i E39 1997
    Automatic ZF 5HP18
  • 10-27-2010, 01:32 PM
    JimCash

    Re: Bleeding the Radiator

    I agree with the answers JimLev gives.

    You must still have air in the system - and probably a leak somewhere. You really should do a pressure test - especially if the leak is internal to the engine.

    Those hoses are shrinking because of the air. When cooling air will contract more than liquid and that is why you are getting enough contraction to cause those hosed to partially collapse. That will not normally happen if the coolant system is mostly liquid.

    And yes - cold is cold - it can take more than 12 hours for these engines to cool and bring the coolant down to the normal ambient temp and pressure. Your 6 cyl may take less time - my 8 cylinder can stay warm for almost a full day in warmer weather.

    You mention "my write up" - this is a short version of what I usually post and it is very important that you include the process of bleeding the heater part.

    See a repeat of my process below - and remember that with the 6 cyl cars it is almost necessary to raise the front end as much as possible while running the engine for a period so as to get all the air to go to the front and up into the bleed area.

    Cheers
    Jim Cash
    --------------
    Cooling system bleed procedure – M62 engine (E39 – 97 version)


    - with cold car
    - top up coolant to proper level.
    - leave rad cap loose

    This stage bleeds air trapped in the heater system.
    - turn on ignition switch to position 2 (no start)
    - set temperature selectors on the climate control to max temp.
    - manually set the fan speed to low (lower end of speed range)
    - start engine (check that climate settings have not changed)
    - after 5-10 seconds of running rev the engine 3-4 times to about 2500 RPM - hold
    there for about 5 seconds each time.
    - shut off engine (should not run for much longer than about 30 seconds - you just want
    to shut if off before it starts to generate any heat and expand the coolant).
    - inspect the coolant level and top up again if necessary.
    - tighten the coolant fill cap.

    This stage bleeds air from the engine, rad and fill tank.
    - now warm up the engine (drive a bit if you wish)
    - with engine running CAREFULLY / SLOWLY open the bleed screw. Hold a rag around the area to prevent any excess splashing. Keep the screwdriver in the slot of the bleed screw so you can close it quickly.
    - you should have some air/steam escape - progressing to some bubbles of coolant.
    - as soon as it progresses to the stage where you are seeing liquid coolant come out then close the bleed screw. Do not over tighten - it is all plastic threads and you can easily turn too far at which point the screw jumps back a thread and you have to re-tighten. Just make it snug with all coolant stopped.
    - when the car is cold again re-check the coolant level and top up again if necessary.

    You may have to repeat the bleed procedure 1 or 2 more times over the next week. Can "probably" skip the stage for the cold start bleeding of the heater system.

    If the level continues to fall below the correct level then have the system fully pressure tested - explaining to your service manager what you have already done.

    It is very important that all leaks be sealed so that the system can operate at full pressure. The engine computer is programmed to keep the coolant temp at about 108C at "most" times (there are exceptions) and the only way it can maintain that temp is if the pressure can be maintained - system fully sealed.
  • 10-27-2010, 12:15 PM
    jimlev

    Some answers (m)

    1. When open the bleed valve I assume the radiator cap is closed and engine still running(?) Yes, closed and engine running.

    2. As in my case steam and bubbles came out intermittently with coolant stream: there was no liquid coolant ONLY. Why?
    You still have air in the system.

    3. After engine cools... --> how cold? overnight? one third of the temp meter? In my case after engine cools (about one or two hours after engine turned off) the upper and lower radiator hose shrinks which will be back to normal only by opening the bleed valve. What and where things have gone wrong? Never have this before with my late 520i/E34/M20/1990.
    Cold as in overnight.
    After a few hours the engine is still hot and so is the air/coolant in it. When you open the bleeded pressurized air is released and the hoses shrink.

    4. After doing so, coolant level keeps dropping despite several top up. Maybe you have a leak somewhere and this is the reason for repeaded fills? Have you done a pressure test on the cooling system?
    Go back and check ALL of the hose clamps, the heater hoses too.

    5. Check coolant level every few days for a few weeks... --> Normally how long will it take to completely empty air from the system?
    For an I6, 3-4 days but it really depends on how much you drive it in those 3-4 days.

    6. Specific question: under normal driving i.e. shift lever at "D" position cooling system appears to work fine and is able to maintain normal temp for several days until it eventually needs top up (average 2 weeks interval) however when shifted to "S" or "M" mode coolant level would be drastically drop (or drained) the following day. I realized this when driving the car and saw the temp needle rise up. This is my long outstanding issue until now. Please help.

    Really? The only thing I can quickly think of it in these modes you are pushing the engine a bit harder so it will develop more heat with will get the coolant hotter. The pressure in the cooling system rises which will make it leak more.
    It's possible your head gasket is bad, but that's just a guess.
  • 10-27-2010, 10:55 AM
    Enrico Tobing

    Bleeding the Radiator

    Here is the bleeding write-up by Jim cash:

    Hot engine
    - take car for a run to get up to operating temp
    - using caution - slowly open the bleed valve (steam and bubbles may come out)
    - close as soon as you see liquid coolant without excessive bubbles.
    - do not overtighten this as they are plastic threads. Just snug till it seals fully.
    - after engine cools check the coolant level again and top up if necessary.

    Check coolant level every few days for a few weeks and top up again if required
    - repeat the Hot engine bleed process again.

    The following are my questions/comments:

    1. When open the bleed valve I assume the radiator cap is closed and engine still running(?)

    2. As in my case steam and bubbles came out intermittently with coolant stream: there was no liquid coolant ONLY. Why?

    3. After engine cools... --> how cold? overnight? one third of the temp meter? In my case after engine cools (about one or two hours after engine turned off) the upper and lower radiator hose shrinks which will be back to normal only by opening the bleed valve. What and where things have gone wrong? Never have this before with my late 520i/E34/M20/1990.

    4. After doing so, coolant level keeps dropping despite several top up.

    5. Check coolant level every few days for a few weeks... --> Normally how long will it take to completely empty air from the system?

    6. Specific question: under normal driving i.e. shift lever at "D" position cooling system appears to work fine and is able to maintain normal temp for several days until it eventually needs top up (average 2 weeks interval) however when shifted to "S" or "M" mode coolant level would be drastically drop (or drained) the following day. I realized this when driving the car and saw the temp needle rise up. This is my long outstanding issue until now. Please help.

    Thanks.

    Enrico Tobing
    528i/E39/1997

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