Re: 533i Over heating

["Scott Buchanan" <87535is@xxxxxxxxxxxxx>]

I had very similar problems with my '87 535is.  I took the "replace it all"
approach (except for the radiator) and ended up with a temp needle that
never exceeds halfway even with the AC on sitting in traffic on a 90+ day.
I replaced the water pump, all water hoses, thermostat (went from stock temp
to 71 degree version), and both radiator temp switches.  In the case of the
temp switches, I bought a lower than stock temp switch for the low speed
position and put a new stock low speed switch in the normal high speed
position.  All this did was cause the fan to kick on at a lower temp and go
into high-speed mode at a lower than stock temp.  The new lower temp switch
and the non-standard thermostat were sourced at BMP.  In addition to all the
parts, I also flushed, re-filled, and bled the cooling system.  Normal
needle position is around 11 o'clock, but I haven't seen it above 12noon
since doing the above.

You indicated that your fan doesn't kick on until the needle is near the red
zone...  The ballast resistor mounted to the fan housing may have failed
which would prevent the fan from kicking into low-speed mode even if the
temp switch in the radiator is working properly.  Bentley can help with
diagnosis, but essentially you jumper the two wires going to each temp
switch to see if the fan will work at both speeds.  If it does, then your
temp switches are likely shot.  There's just tons more info on this subject
out there.  Good luck with the search on the problem.

Regards,

Scott Buchanan
Charlotte, NC
'87 535is

Damian Horner wrote:
>
> I have a 1983 533i which tends to get very hot when sitting traffic on a
> warm day.  The backup fan does kick in, but not normally until the
> temperature guage is almost at the red.  I suspect the fan switch, which
> is temperature controlled has 'moved' over the years and is kicking in
> too high.
>
> Does anyone agree, where is the switch on the engine, and lastly, are
> there any Bentley manuals out there wanting a new home - I'd like to buy
> one and if I can't get one here I'll have to order it from Bavarian
> Auto.
>
> Thanks - Damian Horner.

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