'98 E39 strange overheating

My 528 runs great but the temp guage will suddenly start rising and
light up the red zone in the guage - it stays that way for about a
minute at the most and then returns to normal. It may do this once or
two time I drive the car out. I have noticed that this tends to happen
on an undulating road surface (steeper ups and downs). Sometimes, the
needle rises but does not make it to the red (lighted) zone on the
guage and returns to normal.

I recently flushed & filled the antifreeze with BMW original
antifreeze (diluted 50% with water). Any suggestions will be much
appreciated..Thanks in advance!

"SunK" > wrote in message
...
> My 528 runs great but the temp guage will suddenly start rising and
> light up the red zone in the guage - it stays that way for about a
> minute at the most and then returns to normal. It may do this once or
> two time I drive the car out. I have noticed that this tends to happen
> on an undulating road surface (steeper ups and downs). Sometimes, the
> needle rises but does not make it to the red (lighted) zone on the
> guage and returns to normal.
>
> I recently flushed & filled the antifreeze with BMW original
> antifreeze (diluted 50% with water). Any suggestions will be much
> appreciated..Thanks in advance!


The guage runs to red and you keep going? That's a bad thing.

I would want to be sure the thermostat was not sticking closed.

SunK > wrote:
>My 528 runs great but the temp guage will suddenly start rising and
>light up the red zone in the guage - it stays that way for about a
>minute at the most and then returns to normal. It may do this once or
>two time I drive the car out. I have noticed that this tends to happen
>on an undulating road surface (steeper ups and downs). Sometimes, the
>needle rises but does not make it to the red (lighted) zone on the
>guage and returns to normal.
>
>I recently flushed & filled the antifreeze with BMW original
>antifreeze (diluted 50% with water). Any suggestions will be much
>appreciated..Thanks in advance!

Could be a wiring issue with the sensor... or it could be something a whole
lot worse like an actual cooling system problem.

Have someone watch the gauge while you go tug on the wire to the sensor.
Wiggle it around.... then follow it up the wiring harness and keep poking
and moving it. Unplug the sensor, plug it back in, shake everything and
see if you can find a bad connection somewhere in the system. Then take
the steering wheel off, pull out the gauge package and start fiddling with
the wiring behind it too until you find a bad connection. You may want to
just open all the connectors, clean them with DeOxit, and pack them with
dielectric grease to prevent future problems.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Jan 2, 2:33*pm, (Scott Dorsey) wrote:
> SunK > wrote:
> >My 528 runs great but the temp guage will suddenly start rising and
> >light up the red zone in the guage - it stays that way for about a
> >minute at the most and then returns to normal. It may do this once or
> >two time I drive the car out. I have noticed that this tends to happen
> >on an undulating road surface (steeper ups and downs). Sometimes, the
> >needle rises but does not make it to the red (lighted) zone on the
> >guage and returns to normal.
>
> >I recently flushed & filled the antifreeze with BMW original
> >antifreeze (diluted 50% with water). Any suggestions will be much
> >appreciated..Thanks in advance!
>
> Could be a wiring issue with the sensor... or it could be something a whole
> lot worse like an actual cooling system problem.
>
> Have someone watch the gauge while you go tug on the wire to the sensor.
> Wiggle it around.... then follow it up the wiring harness and keep poking
> and moving it. *Unplug the sensor, plug it back in, shake everything and
> see if you can find a bad connection somewhere in the system. *Then take
> the steering wheel off, pull out the gauge package and start fiddling with
> the wiring behind it too until you find a bad connection. *You may want to
> just open all the connectors, clean them with DeOxit, and pack them with
> dielectric grease to prevent future problems.
> --scott
> --
> "C'est un Nagra. *C'est suisse, et tres, tres precis."

If it was a whole lot worse would not the "Check Engine" light up?
This has been going on for weeks now..I do suspect it could be limited
to a sensor issue..what other symptoms should I look for if this was a
whole lot worse than a sensor issue..?

"SunK" > wrote:
> .......
> I recently flushed & filled the antifreeze with BMW original
> antifreeze (diluted 50% with water). Any suggestions will be much
> appreciated..Thanks in advance!

Are you sure you bled the cooling system properly after the
refill? It is hard to get all the air out, and if you haven't done
it before, odds are it isn't completely bled.

SunK > wrote:
>
>If it was a whole lot worse would not the "Check Engine" light up?

Eventually, once the engine has been melted into slag.

>This has been going on for weeks now..I do suspect it could be limited
>to a sensor issue..what other symptoms should I look for if this was a
>whole lot worse than a sensor issue..?

None. The reason you have the gauge is to indicate to you that something
is wrong. If there were other easy symptoms of overheating, you wouldn't
need the gauge.

It _is_ possible you have a failing thermostat, bad water pump, or an
intermittent blockage. I'd change the thermostat anyway just in case,
and I would also make VERY sure the system is completely bled. But I
would look for a sensor problem, especially if the problem happens on
the highway as easily as at idle.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article
>,
SunK > wrote:
> My 528 runs great but the temp guage will suddenly start rising and
> light up the red zone in the guage - it stays that way for about a
> minute at the most and then returns to normal. It may do this once or
> two time I drive the car out. I have noticed that this tends to happen
> on an undulating road surface (steeper ups and downs). Sometimes, the
> needle rises but does not make it to the red (lighted) zone on the
> guage and returns to normal.

The temperature gauge in these doesn't react exactly to true temperature.
It will stay exactly midway within a big range of actual temperature - ie
those to be expected in normal use.
There is a way of making the dash display (obc) read true temp in
degrees. You'll need to Google for this. If that is showing overheating
too I'd guess you have a 'mechanical' fault - if not it's a software etc
thing.

--
*Virtual reality is its own reward *

Dave Plowman London SW
To e-mail, change noise into sound.

in article
, SunK at
wrote on 1/2/09 11:12 AM:

> I recently flushed & filled the antifreeze with BMW original
> antifreeze (diluted 50% with water). Any suggestions will be much
> appreciated..Thanks in advance!


Water pump is failing as the bearings wear out ... usually there is a water
leak down the bearing hole when that happens ... of course that is when it
fails not on the way to failing.

Other plan is that your fan belt is slipping (on hills under load) and just
needs to be tighten.

Of course you have heard about sensor problems, but that seems a long shot,
usually electric stuff works or it don't ... I don't think you have a hot
short here making for higher readings.

With your back yard mechanic thingy going on with the radiator flush ...
seems that you did not do a spot on correct job of bleeding the air out of
the system as some have said ... maybe you did and there is no air to bleed
out like it was a Ford ... as otherwise they would have to put in a bleeder
value like on brake systems if that were the case I would think.

Either way ... you need to get your car into a certified BMW mechanic and
have it sorted our correctly or watch your engine melt on the highway one
fine day. That Red Light goes on for over a minute you are a slag heap on
the road ... get it fixed ASAP if you want to keep your engine.

Burn that out ... toss the car away.

The engine is worth more then the car.

sumbuddie wear blind sea

On Jan 3, 9:18*am, "Alan B. Mac Farlane" > wrote:
> in article
> , SunK at
> wrote on 1/2/09 11:12 AM:
>
> > I recently flushed & filled the antifreeze with BMW original
> > antifreeze (diluted 50% with water). Any suggestions will be much
> > appreciated..Thanks in advance!
>
> Water pump is failing as the bearings wear out ... usually there is a water
> leak down the bearing hole when that happens ... of course that is when it
> fails not on the way to failing.
>
> Other plan is that your fan belt is slipping (on hills under load) and just
> needs to be tighten.
>
> Of course you have heard about sensor problems, but that seems a long shot,
> usually electric stuff works or it don't ... I don't think you have a hot
> short here making for higher readings.
>
> With your back yard mechanic thingy going on with the radiator flush ...
> seems that you did not do a spot on correct job of bleeding the air out of
> the system as some have said ... maybe you did and there is no air to bleed
> out like it was a Ford ... as otherwise they would have to put in a bleeder
> value like on brake systems if that were the case I would think.
>
> Either way ... you need to get your car into a certified BMW mechanic and
> have it sorted our correctly or watch your engine melt on the highway one
> fine day. *That Red Light goes on for over a minute you are a slag heap on
> the road ... get it fixed ASAP if you want to keep your engine.
>
> Burn that out ... toss the car away.
>
> The engine is worth more then the car.
>
> sumbuddie wear blind sea
>
>

Thanks all - appreciate the responses. There is while powdery residue
on the neck of the coolant tank, on the hose and the underside of the
hood. Clear indication of coolant leak given that the coolant level
had reduced significantly since I had last filled it. The service shop
says they need to replace the water pump and thermostat - total cost
of about $600 !! Does that sound right..?

"SunK" > wrote in message
...

Thanks all - appreciate the responses. There is while powdery residue
on the neck of the coolant tank, on the hose and the underside of the
hood. Clear indication of coolant leak given that the coolant level
had reduced significantly since I had last filled it. The service shop
says they need to replace the water pump and thermostat - total cost
of about $600 !! Does that sound right..?
-----------------------------------------------------------------------------

The price doesn't seem out of line as I recently paid around $510 for a
thermostat and coolant replacement (with a BMWCCA discount) on my E46.

Tom