Coolant temperature sensor

[TestMate]

Right...

F@cki'n hook nooses
R7500
AND the whole Fan assembly
no wonder I don't drive a BM

Anyway...You havent done anything wrong! huh
A multimeter will not hurt your ECU or the damn regulator.

Try harder at the scrapyards.

In the meanwhile:

Connect the b/g wire (THE ONE that is coming from the Fan Regulator. NOT the rest of it that goes to the ECU harness!!!) to earth (battery -)
Note the result.
Then connect it to the bat +. note the result.
If no change the thing is cooked.

I'm not sure what signal the ECU sends to it...it looks like a series of pulses (in leimns terms) because your multimeter only reads 5-6v.
You need an Osciloscope to see what's happening. Basicaly the shorter the 'pulses' the faster the speed (something to this extend).
Let me know.

 

[spacemanwayne]

Yeah man, i didn't expect that price for a fan, and another R1000 in labor to remove 4 clips, unplug a connector, pull the fan out, and put the new one in, literally a 10 minute job, CRAZY!!! I am planning on selling the car, spending that much on something like a fan makes no sense to me, and this leaves me wondering what i would pay to change major things.

I guess thats how they make their money Ah well!

Cant wait for the Joule to get released, thats going to be a nice run around car.

I will keep looking for a fan though, there is a few places that have em.

I will do the connection of the b/g wire as you said I should on Thursday and will post the results.

Thanks TestMate

 

[Palimino]

Yeah that can't be the thermostat because the engine wouldn't lose heat at all but it's strange that the fan turns on when the car is off, modern cars don't do that (since there is no point)...

This happens (not when the engine is cold). When you halt and switch-off the engine, it still has latent heat. The temperature can still rise when the engine is off. The fan switches on when the ignition is off to control this.

Incidentally, if the fan runs permanently, the engine will run cool. Thus it will run (fuel) rich. You may be consuming more fuel (not hugely significant, however).

 

[Claymore]

Incidentally, if the fan runs permanently, the engine will run cool. Thus it will run (fuel) rich. You may be consuming more fuel (not hugely significant, however).

It shouldn't run cool. The thermostat controls coolant temp, not the fan. The fan may cool the radiator, but if the thermostat reduces circulation through the radiator, the correct temp will be maintained.

 

[spacemanwayne]

Interesting point Palimino and Claymore. I did notice that the car is now running extra extra cool with the fan on all the time, but interesting enough, if i drive a bit hard, it almost makes it to the half way mark. But once i take it easy, it cools down to just passed the first white line after the blue marking. If i use the aircon, it will sit at the half way mark.

Looks like i may need a thermostat replacement as well?

 

[Palimino]

Should i measure in ohms?

Don’t ever measure voltage in ‘ohms’. Ohms is a unit of resistance. You may blow-up your meter.

 

[Palimino]

It shouldn't run cool. The thermostat controls coolant temp, not the fan. The fan may cool the radiator, but if the thermostat reduces circulation through the radiator, the correct temp will be maintained.

Uh-uh. The thermostat controls water flow. When the engine is cold, the thermostat is closed. Until the engine warms-up, the thermo. stays closed. Under normal driving conditions the engine runs too hot for the thermo. to stay closed. It opens but the fan is running continuously so it perpetually cools the water in the radiator. The engine runs cool. QED.

 

[spacemanwayne]

I think i understand what you are saying. I thought that whether the fan is running or not, even at high speed all the time, the temperature of the engine will always be maintained by the thermostat, theres alot more to this isnt there.

 

[Palimino]

I think i understand what you are saying. I thought that whether the fan is running or not, even at high speed all the time, the temperature of the engine will always be maintained by the thermostat, theres alot more to this isnt there.

The thermostat (on a car) controls coolant flow. When the engine is cold, flow is restricted to the engine block. When the engine warms-up the thermostat opens and coolant circulates through the radiator. When the engine becomes too hot for airflow through the grill to cool the coolant in the radiator, the fan switches-on to assist (via another thermostat). The fan shroud channels the airflow and makes the fan more efficient. Unless it is an extremely hot day and you are stuck in traffic, cooling should be adequate.

What may be confusing you is that there are two thermostats. One controls the water flow and one switches-on the fan when required.

 

[Stokstert]

The thermostat (on a car) controls coolant flow. When the engine is cold, flow is restricted to the engine block. When the engine warms-up the thermostat opens and coolant circulates through the radiator. When the engine becomes too hot for airflow through the grill to cool the coolant in the radiator, the fan switches-on to assist (via another thermostat). The fan shroud channels the airflow and makes the fan more efficient. Unless it is an extremely hot day and you are stuck in traffic, cooling should be adequate.

What may be confusing you is that there are two thermostats. One controls the water flow and one switches-on the fan when required.

I can't agree with your statement that there are two thermostats. There is one thermostat, which controls water flow and a thermo-switch which controls the switching of the fan. Some thermo-switches are multi mode for different fan speeds.

 

[mic_y]

hhhm, since there seem to be some pretty knowlegable people here, let me also ask a question. I have a BMW 328i (E36) '98 model, and i have noticed that in winter the water temperature varies a lot depending on speed and temerature. in summer, the temerature sits roughly in the middle all the time, but in winter at night, if driving at high (100km/h+) speeds, it barely gets over the first white line. Is that normal?

 

[spacemanwayne]

Connect the b/g wire (THE ONE that is coming from the Fan Regulator. NOT the rest of it that goes to the ECU harness!!!) to earth (battery -)
Note the result.
Then connect it to the bat +. note the result.
If no change the thing is cooked.
.

Hey there Testmate. I just did this test.
I created 3 new wires, positive, negative and b/g. First I connected the negative together with the b/g to the batteries negative terminal from the fan and the positive to the batteries positive terminal from the fan and the fan still runs at high speed all the time. Then i removed the b/g wire from the negative and connected it to the positive terminal of the battery and absolutely no difference at all.
That damn stubborn fan continues to run fast all the time
Guess I got to replace the fan shroud, eeeek:erm:
Well atleast we know exactly where the problem is and how to trouble shoot it.
I am going to get another fan, hopefully this weekend, i will post the outcome once i get it and have it installed.
Thanks a mil Testmate!!!!

 

[Stokstert]

I would say your thermostat is stuck in the fully open position.
In summer the fan swithing on controls the upper limit, i.e. in the middle/normal position where it should be. In winter you don't reach fan switch-on-temp and the surrounding temperature and driving speed varies, so your temp reading varies (to under normal) accordingly as you have no thermostat control for the lower limit.

 

[mic_y]

I would say your thermostat is stuck in the fully open position.
In summer the fan swithing on controls the upper limit, i.e. in the middle/normal position where it should be. In winter you don't reach fan switch-on-temp and the surrounding temperature and driving speed varies, so your temp reading varies (to under normal) accordingly as you have no thermostat control for the lower limit.

ok sounds quite plausible, now, should I try and do something about it, or is it not a major trainsmash and I can keep driving around as is (This is from a student perspective, where cash is definitly a limit).

BTW, is there any way to test the thermostat and possibly fix it, without going to BMW?

 

[Stokstert]

It's not a trainsmash but I would attend to the problem, as it's always better to have the engine running at controlled and optimum temperature. If costs are a concern, maybe go to a reputable workshop or mechanic other than the agents,.
I would not suggest to try to fix it yourself without a knowledgeable person to hold your hand, as it can become quite expensive if you make a mistake in identifying and fixing the problem.

 

[TestMate]

It's not a trainsmash but I would attend to the problem, as it's always better to have the engine running at controlled and optimum temperature. If costs are a concern, maybe go to a reputable workshop or mechanic other than the agents,.
I would not suggest to try to fix it yourself without a knowledgeable person to hold your hand, as it can become quite expensive if you make a mistake in identifying and fixing the problem.

To MIC_Y

Stokstert is spot on!
The car either don't have a Thermo or it's stuck open or sluggish.
Should be replaced by a man who knows what is doing.
If you plan to keep the car...change it as it will save you petrol in the long run.

 

[TestMate]

Hey there Testmate.
Well atleast we know exactly where the problem is and how to trouble shoot it.
I am going to get another fan, hopefully this weekend, i will post the outcome once i get it and have it installed.
Thanks a mil Testmate!!!!

Well...sort of...this type of diagnosing is best done with a scope.
Anyway...give yourself a favour and connect the new fan immediately after you buy it to the car plug.
What I'm trying to say is...you want to know if there is any difference.
If not...return it straight away and get your money back.
For this to work the car has to be cooler...so wait some time before you buy and try the new fan.
Or better yet get BMW to try one for you...just to make sure that's the problem.....after that you know what to do