Heater valve

[batsbats]

Did you end up fixing this?  I have a similar issue.  Sometimes when Im sitting in traffic like today (60-65 ambient), I can make the temp gauge move from 2 mm RIGHT of the Middle, to directly in the middle.  

Essentially I can change the temp gauge reading by changing the hvac control from blue to red and turning the fan to 1-4 speeds.

The 88C thermostat should put the normal operating temperature evenly in the middle correct?

[pifane]

This afternoon Ive changed my water pump...flushed 3 time my system with special product....

So, new fan clutch, new water pump, clean system, new hose and still overheat  ....This week I will put an original bmw 88 degree I got from the bmw official dealer....

If after that it will not work, I will check at all the f*cking stupid dumb bmw sensor all around the engine and in the car.....

And if my engine is still overheat after that.....ILL BURN IT!!!!!!!!!!!!!!

[pifane]

As usual, im replying to all my messages to help people all around the internet with m42 engine trouble...

I got a question right now about my overheating prob:

This afternoon, when I was opening the drain plug, I noticed that the fan in the front of the engine was not alive....So, I dont think its normal...And Im not sure about this, but on january, when Ive repair my profile gasket, Ive removed the AC compressor.......AND...its since this moment my engine is overheating....

Someone have an idea?

[EN318isPDX]

Go buy one of those laser temp gauges and check your coolant hoses and engines temp? Maybe your gauge or temp sensor is fried

[nicknikolovski]

maybe your gauge is just reading wrong - replace the coolant temp sensor. Actually replace both as there are two. One for the gauge and one for the fuel injection system.

[pifane]

This is the part of the discussion where Im very poor. Ive looked all around the engine and I only find the sensor at upper right side of the radiator....(me and sensor = 2)

If someone can tell me where is the possible faulty sensor and the name of it for know what to replace...

Also, I dont think my gauge is wrong because my engine is very hot when touching it after running a moment.

[colin86325]

Is anything blocking the ventilation to the radiator?

Are the hoses routed correctly?

Are you sure the gauge sender is ok?  The sender wire could be touching a ground somewhere and sending an "overheat" signal to the gauge.

[nicknikolovski]

Ok, both the temperature sensors are on the right hand side of the cylinder head just under the intake manifold. There are two sensors, one for the temp gauge and the other is for fuel injection and engine management. Check out realoem.com for a specific part no. and diagram for your vehicle. I would replace both. They are not expensive but can be a bit of pain to get to.

The other sensor you are talking about on the left hand side of the radiator (opposite side to the expansion tank) is the auxillary fan thermoswitch. I would also replace this.

Also before replacing anything, did you pressure test the cooling system?

[pifane]

I have cleaned my system with prestone superflush 2 time, and cleaned 2 time with water. My water pump is working fine and my system have a good circulation.

This is what I dont understand........If circulation is okay, why my engine is overheating? If I change the sensor, what will change? What's sensor is controling?

[pifane]

It's very weird. When im on idle, the temp is okay......What the f*ck is happening here....I will check with laser temp gun

[nicknikolovski]

The two sensors on the cylinder head control the following: one gives the temp gauge signal and the other one gives the coolant temp signal to the engine ecu.

The third sensor which is located on the side of the radiator controls the electrical fan behind the front bumper.

This is a strange one because the viscous fan will cause overheating at idle and in stop- start traffic. The electrical fan will cause overheating at just over operating temp because it is not cutting in too help out for additional cooling. Check the aux switch on the radiator and replace it, see if that fixes the problem.

The radiator, hoses and water pump will usually cause overheating problems because they are leaking or damaged. If you've replaced these and bled the system properly there should not be a problem.

Have you installed the correct thermostat? If so is it in the correct way?

Also I would check your cooling system using a pressure tester. Leave it connected overnight and see if the system holds pressure.

[pifane]

Thank for the reply, this will be helpfull. I will replace the thermostat tomorrow if I have time.

Do you have an idea where I can buy these sensor? On BMAPARTS i only find "Water Temperature Sensor/Fuel Injection" and the O2 sensor. the "Water Temperature Sensor/Fuel Injection" is the one I need?

[nicknikolovski]

What year is your 318is?

[nicknikolovski]

I would replace thermostat first, then the water temp sensor/fuel injection second, then if after replacing these if it is still overheating, replace the auxillary temp switch on the side of the radiator.

I can find some part no's for you if you give me the month and year your 318is was made?

[pifane]

I will check for the month in 2 hours