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.
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.
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.
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.
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.
Spray with soapy water and look for bubbles
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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!
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.
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.
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.
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
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.