My wife complained recently of het E36 318 overheating on her way home in
traffic. I checked the coolant and checked to see that the big electric fan
came on when she used the AC. Both were fine but problem persists.

I did find this weekend, that the temp came down a bit if I switched on the
AC. On the open road at 120+ Km/h the temp is rock solid in the middle, but
as soon as I hit traffic the temp goes up. It even went into the red once
and came back out of there quite quickly after switching on the AC. I
limped home freezing behind the wheel ;-)

Where do I start looking?

I suspect that some fan should be working which is not...

On Mon, 19 Mar 2007 12:13:17 +0200, "MW de Jager" <mwdejager (AT) privatemail (DOT) me.uk>
wrote:

The big fan at the front is ONLY for the A/C and is not operational without the
A/C being ON.

You should have an engine fan with a fluid coupling that restricts the speed of
the fan. This can seize causing noise (roar) and / or rip out the radiator fins
as the tips bend at high speed or not work at all causing OVERHEATING.

Then again the previous owner might have removed it for extra speed - all 2mph
of it!


Sir Hugh of Bognor

The difference between men and boys is the price of their toys.

Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen
hsg (AT) h-gee (DOT) co.uk
Bognor Regis, W.Sussex, England, UK

Nedavno hsg (AT) h-gee (DOT) co.uk napisa:


Are you sure? On E30 that fan is ON on low when A/C is on. But there
are also two thermo-switches in the radiator that turn on the fan on
low / high - depending on temperature.

And this is auxiliary fan. Since temperature is OK on highway driving
I suspect that the main (mechanically driven in E30) fan does not
operate as it should. Perhaps the fan clutch is broken?


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----- Original Message -----
From: "MW de Jager" <mwdejager (AT) privatemail (DOT) me.uk>
Newsgroups: alt.autos.bmw
Sent: Monday, March 19, 2007 5:13 AM
Subject: 318 overheating in traffic



JoshIII suggests:
Since you dont have a cooling problem at highway speeds, this indicates your
water pump is still good.

An inexpensive test would be to install low temp thermostat
to see what difference it makes with the idling & in traffic temp.

If the in traffic temperature still pushes towards the maximum, this would
indicate some other restriction in the coolant or air flow through the
radiator, or else a radiator that is too small to handle the load.

If car/radiator is relatively new, then you might consider looking for a
slightly oversized aluminum radiator for the car.

This is what I did for my old E21 1980 320i (4-cyl 1.8L), and it cured my
overheat problem for good.

With air conditioning condensers in front of the
radiator, this restricts air flow to the radiator.
On hot days with A/C running, this even preheats the
air going to the radiator, a double whammy.

You might be able to find an oversized aluminum radiator
for the E36 (Google search: E36, custom radiator) that will interchange with
the OEM with little or no modification to the mounting saddles. If you
find a custom radiator already designed for the E36 from a reputable
custom/racing radiator manufacturer (i.e., Ron Davis Racing Products,
others), the prices will be lots better and lots less trouble than designing
one from scratch.

Pictures of the oversized radiator I designed for my old E21 have been
posted at www.bmwboard.com Look for posts from ID: Z4madehere

Good luck!

JoshIII
upstate south carolina
josh3i at hotmail . com

I think your fan clutch is failing.

You have a fan tht is driven by the fan belts on the front of the engine.
There is a clutch (viscous coupling) that is supposed to lock up as the temp
rises. When the clutch locks up, the fan is physically driven by the belts,
the rest of the time, the fan can easily be stopped from rotating, and slow
speeds (idle speeds, not traffic speeds), the fan might not even spin at
all. Should the fan spin slowly, or not at all -- even worse -- the engine
will over heat. This condition will right itself when traffic speeds go back
up. What happens then is that the air flow over the radiator take splace
because the car is moving, but in stop-n-go traffic, the air flow is caused
by the fan that has stopped working.

The AC turns on an auxiliary fan, this can be what is bringing the temps
down for you.

In my 325i, the fan clutch costed about $175. I was having other work done,
and I had my mechanic take this job too; which explains to me why the cost
was high. I think that if you have the skills to do this job, you should be
able to get the clutch for under $100.













"MW de Jager" <mwdejager (AT) privatemail (DOT) me.uk> wrote

"Yvan" <me (AT) privacy (DOT) net> wrote


DING DING DING
We have a winner. The Fan Clutch is broken.

On Mon, 19 Mar 2007 17:09:34 GMT, "Jeff Strickland" <crwlr (AT) verizon (DOT) net> wrote:




Sir Hugh of Bognor

The difference between men and boys is the price of their toys.

Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen
hsg (AT) h-gee (DOT) co.uk
Bognor Regis, W.Sussex, England, UK

On Mon, 19 Mar 2007 17:05:33 GMT, "Jeff Strickland" <crwlr (AT) verizon (DOT) net> wrote:

Not quite true Jeff. The viscous coupling is there to prevent the fan running
at engine speed - It is designed to limit the speed of the fan. It will
actually draw far more air at idle - mid range than pro-rata at high revs. If
it ever were to run at top belt speed it would actually rip out the radiator
fins.

I had this happen on a Nissan and an earlier E3 3.3Lia BMW

TIP: When working with a viscous fan coupling DO NOT EVER lay them down but
make every endeavor to keep them standing UPRIGHT.

The fluid is a silicone mix and when laid flat the fluid seeps past the seals
(silicone is very slippery) and will DESTROY the bearings that allow the speed
differential.

The couplings are always transported stacked like LP records VERTICALLY and
should always be stored as such. I always used to hand then with welding rod
from a hook on the wall when removed from a vehicle and NEVER had a failure
after I found this trick from, believe it or not, the BMW dealer that I got my
E3 radiator and fan clutch/viscous coupling from in 1980.


Sir Hugh of Bognor

The difference between men and boys is the price of their toys.

Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen
hsg (AT) h-gee (DOT) co.uk
Bognor Regis, W.Sussex, England, UK

Thanks for everyone's replies, but I'm still no wiser.

My E36 328 has the mechanical fan with clutch that runs off the engine belt.

The E36 318i South African built with Single OHC, does not have an engine
driven fan, at least my wife's does not. It only has an electric fan which
I supect is called the auxilliary fan. In the fuse box, it states that the
1996 4 cylinder models have fuse no 48 for the aux fan. This fuse however
is supposed to be underneath the steering wheel and apart from one gazillion
wires and wire connections I cannot find a fuse there. :-(

There a 3 wires coming from a device sitting on the side of the radiator,
which I presume is a temp sensor of some kind. These wires have been
stripped by someone before, I don't know why. The red LED on the temp guage
comes on fine, so why would the aux fan not start running soon enough? The
fan runs fine when the AC is on though.

Any suggestions

Kind regards
MW

"MW de Jager" <mwdejager (AT) privatemail (DOT) me.uk> wrote

On Tue, 20 Mar 2007 09:40:01 +0200, "MW de Jager" <mwdejager (AT) privatemail (DOT) me.uk>
wrote:

IFRC all the BMWs have mechanical (viscous or even thermo-clutch pre 1978) fans
fitted. It is very likely that some previous owner did away with it considering
the fact he lived in the middle of nowhere so town driving didn't;come into his
repertoire!

Lets have the last 7 digits of the chassis number (OFF LIST if you prefer) and I
see if the vehicle ever had a mechanical/viscous fan fitted.



Sir Hugh of Bognor

The difference between men and boys is the price of their toys.

Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen
hsg (AT) h-gee (DOT) co.uk
Bognor Regis, W.Sussex, England, UK