318 overheating in traffic

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...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nedavno snipped-for-privacy@h-gee.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?
--
___ ____
/__/ / \ ** Registrovani korisnik Linuksa #291606 **
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
napisa:

DING DING DING We have a winner. The Fan Clutch is broken.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mar 19, 3:29 pm, snipped-for-privacy@h-gee.co.uk wrote:

In an unfortunately overly obfuscatory manner ... =;^D -- C.R. Krieger (Been there; done that)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

On my E39 you can clearly hear when the fan clutch locks up at low speeds - the fan noise increases.
--
*Speak softly and carry a cellular phone *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
----- Original Message -----
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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.

Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Modern ones vary the amount of 'slip' allowed - you can tell if you have this type by the clock spring on the back which sort of measures the air temperature being drawn through the rad and varies the drive. And when they get hot they do near as dammit lock up. I've had one fail locked solid and the noise was no greater than when it locked when hot.
If you have one on the bench you can check this operation with a hot air gun (paint stripper).
--
*Stable Relationships Are For Horses. *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Last 7 digits of VIN AV70871
Thanks in advance
MW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nedavno MW de Jager napisa:

You should have one: http://www.realoem.com/bmw/showparts.do?model 98&mospidG492&btnr_1244&hg&fg5
--
___ ____
/__/ / \ ** Registrovani korisnik Linuksa #291606 **
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I already sent him a picture with part numbers..........
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 snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@h-gee.co.uk wrote:

So it seems we were all right. It is a *faulty* fan clutch. And the good news is that he won't have to worry about removing the old one. ;-)
To the OP, an alternative would be to rig up a thermostatic switch of some sort to sample the coolant temp in the radiator and wire that to the aux fan. That fan is certainly powerful enough to take care of your cooling needs and then when at speed and the rad temp falls it will switch off and save power. Worth considering...
--
-Fred W

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Funny you mention that Fred. once upon a time - long long ago.....
I designed an electronic fan control for auxillary fans - works very well even now and I give the circuit to my school kids in the electronics classes to build and test.
If you want the pictorial I can email it but if you guys want it email me off list and I'll sen it all at once to save me time. It'll came as a jpg.
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 snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mar 21, 6:21 pm, snipped-for-privacy@h-gee.co.uk wrote:

Hi All
Problem is solved in the meantime by an auto-electrician. The car in question does not have an engine driven fan, but the large electric fan is a 2 speed model which runs faster when the AC is on and switches on as the car's coolant temperature requires.
According to the autoelec, the main problem was air in the cooling system, which caused the temp sensor not to work properly. Apparently 2 to 3 liters low on coolant due to air. Bled system properly and now is 100%, no more overheating.
But now none of the controls for the airflow inside the car works. The LEDs come on but airflow stays the same. Is this due to that stupid capacitor on the control circuit that needs to be replaced?
Later MW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.