635 Running Hot

[Pearson-Franks Family <pearsonf@xxxxxxxxxxx>]

Hi, Ray.

Most of the suggestions I have require that you violate an
assumption you have made in your note!  Sorry about that,
but here they come:

1)  Blowing the coolant makes me think of pressurization
    problems.  Have you done a pressure test?  Does it hang
    onto the 1 bar for 20+ minutes?  Can you put on the
    pressure tester and let the engine get hot to see if
    it tries to go over 1 bar?  These tests are looking
    for either lack of pressurization (coolant boils at
    a lower temp, system is less efficient) or a leaky
    head gasket (I know, I know . . . 30 years, etc.)
    that would pressurize the coolant.
2)  Are _both_ speeds of the pancake fan working?  You can
    short one, then the other sensor on the side of the
    radiator to trigger the relays and fan.
3)  When the car is hot, does flipping the fan (not running,
    of course) give you significant resistance - it does not
    coast at all?  (Clutch could still be bad).
4)  Don't know of a high-pitch fan, but Metric Mechanic sells
    higher volume water pumps, as well as higher ratio
    pulleys to pump more coolant.
5)  When you are not overheating, where does the temp guage
    hang out, and what thermostat do you have installed?  The
    stock 75C thermostat will run at about 10:30, given normal
    guage and sensor specs.
6)  And yes, they _do_ run hot in those circumstances.  The
    BMW shop manual for the era suggests setting up large fans
    to move air into the radiator if you have to idle the
    engine for a long time.  But you should be able to stay
    out of the red!

Just some heretical thoughts, Larry F.

>Date: Sat, 31 Jul 1999 22:09:19 EDT
>From: Dogkip@domain.elided
>Subject: 635 Running Hot
>
>Bought a 88 635CSI in Feb. to replace an 85 that met an unfortunate demise on
>a Dallas freeway.  I had the head gasket on the 88 replaced by a mechanic
>with 30 years BMW experience, and at the time he didn't think I needed a new
>radiator.  When the weather started getting warm in Dallas, (over 90F) the
>car started blowing antifreeze from the overflow tank on a consistant basis.
>I put a new Behr radiator in wihich stopped the dumping of antifreeze, but
>with the weather hot (100F+) the temperature gauge needle gets right up to
>the red zone, when the car is stopped in traffic.  I did not have that
>problem with the 85.  Any suggestions on how I can get that temp. down?  It's
>no fun having to constantly monitor the temp gauge when in traffic.  The
>auxillary fan works OK and the car has a new fan clutch.  Driving with the AC
>off is out of the question.  Are there aftermarket items that can help such
>as a fan with a greater pitch?   Do most 6335's run hot when in traffic (stop
>and go) in hot weather?
>
>Looking for suggestions.
>
>Ray
>
>

Larry Franks
Issaquah, Washington
'95 540i/6
'86 535i
'83 245 GLT  (Swedish iron)

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