-----

Here's a few things (and they could be redundant, but) -
1. The instrument cluster may be faulty  (I have some spares!)
2. Are you SURE it's getting that hot?  (if there's air in the coolant
system, the gauge jumps when the air bubble hits the sensor)
3. If the radiator has a blockage (but then it wouldn't cool for days then
act up)
4. The coolant/water ratio needs adjustment
5. It's just too damn hot and humid (my sister in Biloxi says it is)
6. There's some added resistance somewhere creating an artificial reading
7. Pull the cluster and check the 3 rear connectors for fit

Let us know. And can you send me a pic or two of the engine bay?
Bill in Omaha
'86 535i

  Okay, it did fine, fine for days...then it did something similar,
though not as severe, I think. When it does it, the temp needle had
usually climbed...cloom...clum...whatever...but not into the overheat
range. EVERY other car I have ever owned didn't have a problem at this
point. Then it does this weird surging thing. It has an economy meter
from 0 to 40 mpg and that needle swings back and forth. Still it seems
like as long as the temp needle stays in the proper area it runs ok. I
don't mind replacing parts, the car was free, but I'd like to do
something that might work. I've done everything mentioned above.

  I have a new temp gauge sender(not installed yet)...only because
I'd like to know if it's actually overheating. But reading other
forums...fora...whatever, I saw a suggestion for a throttle position
sensor. Sometimes they get grumpy when the engine bay heats up. Coil?
Bad gas? Anything?

mike
88 528e...the tramp!

<Joe Pesci>
Okay, okay, okay, I think I got it!
</Joe Pesci>

I did replace several things...all of which needed a good replacing.

At first, on the advice of a mechanic I replaced the air flow meter.
Nothing

Coolant temp sensor: needed it!!!! Old one disintegrated.
Nothing

Thermostat, original!!!! Needed it!
Nothing

While I was there, several vacuum lines, one of which went to the fuel
pressure regulator...'cos it was all crumbly. I was thinking...low
fuel pressure?

I had already recently replaced fuel filter and plugs.

Cap and rotor...might have been original :-< pins nearly cut in half!
Pitted, horrible
Nothing

Rearranged various relays (fuel pump relay) if appropriate.
Nothing

It was still overheating from time to time... which corresponded to
its poor behavior.

At first glance it looked like the fan clutch was ok. But one time, I
looked at it, it didn't seem quite right. So in one of my southern
"Hey yall! Watch this!" moments, yet without any "y'all "to watch it
or apply a tourniquet if I was wrong...I stopped the fan blade with my
bare hand while it was overheating. Excellent, said I!. Well, only
after noting what a dumb a.s thing that just was. I put a new clutch
on it.

The temp needle is absolutely rock steady. It never goes above medium.
and it runs great! Better than before. I zipped around the
neighborhood, frightened the children, scared the pets, stunned the
farm animals. It wouldn't act up. I almost wouldn't have believed it.
I'm not disappointed. Everything I put on, it needed. Even the
previous air flow meter was the wrong part number. At least now it was
one from the same model!

Thanks to Bill for your input. I'll let you know if it continues to be
a lady or a b***h! LOL

(posted and emailed)

mike
a new regular?!
88 528e

Alright all ye who are strong in BMW-fu

98.4 percent of the time this car runs absolutely fantastic. The other
times it acts as though it is overheating then stumbles and runs quite
poorly. The temp needle climbs, it stumbles, won't accelerate, then a
few minutes later it clears up and again...runs great. I have replaced
the thermostat. I have, but have not yet replaced, the coolant temp
sensor. I have replaced the airflow meter, on the advice of a
mechanic. Fortunately, it was cheap...(EBAY) but it made no
difference. I love the car...It's in great shape...but HELP!