Hello, I have a 1998 320 S, the temp is always below half, and most of the time, quarter,one of the houses blown up all of the sudden, went to change it, found out there is this thick creamy colour inside the rad. when I added water after changing the hose, that subastance flooding up,,is it the begining of a headgasket,? then drove the car for 3 mints some how lost all the oil in the engine from below the right side,the car shutdown by its self, try to started, for two seconds, the power is so low,even the battery new, then found it all the oil leak after try to started,, is engine gone with wind already?thanks for your time in replying.

How fast is 'very quickly'? is it 2 to 3 minutes?, 10 minutes?, 30 minutes?, More? Did you replace the thermostat while you had the housing removed? It is always worth changing it at the same time as then you know there is a working one fitted. Are there any wire connections to the housing? Check you have reconnected it the correct way around.
Another cause could be a faulty water pump. If it isn't pushing the coolant around properly the engine will heat up very quickly. Is there a whine noise coming from the belt end of the engine? Are you getting any coolant leaks from that end of the engine?

If the engine temp exceeds the limit the computer can kill the ac. If the cooling fan stops working the engine temp can go up and also stop the ac from being cold.
Do you know if the cooling fan is working when the problems happen ?

Testing the thermostat would be my first suggestion. If you can remove the thermostat (when cold), boil a kettle and fill a suitable vessel with boiling water. Carefully put the thermostat into the water and see if it opens (it may take a couple of minutes). It may be stuck open, or a previous vehicle owner may have even removed it (may not be possible on some vehicles). There is a small possibility that the actual temperature sensor is faulty but this is quite unlikely.

Hello jasonandc863,

1. remove the two screws and air inlet resonator see figure below.



2. Loosen 3 clamps holding air cleaner housing half together.

3. Remove left half of air cleaner housing.



4. Remove filter element from air cleaner housing.



Reverse order to install.

I hope this helps.

Regards,

netvan

That is a good temperature reading. If it ever gets up pas the three quarter mark, then you have a problem. Although most vehicles read at the half-way point on the temp. gauge. Hope this helps, James Booth PLEASE RATE THIS!!! :)

could be thermostat partially opening only quarter way,what happens is......your coolant sit's in radiator and stay's cool and the other half is warm in engine then it will transit when you accelerate (pushing that sudden change of temp in coolant to your Ect and then your knock and Ect send a derastic message to your brain saying advance and rich out ,I found out the hard way, IT LICK"S MAN!! put stat in boiling pot of water and watch it open and how far is the tricky part,it may open....****!!!!! with restrictive and tricky results to your ECT,the port in your thermostat was designed for a certain gph and in lamen terms set as timing for flow ratewhen you cruise it bucks or what the start kinda running over 2200rpm then bam! then back to chitty land! right???

Check the cooling system for leaks...when the heat goes cold like yours did it usually is caused by the coolant level being so far below normal that it won't flow through the heater core. A blown head gasket can also drive coolant out of the system but I's check for leaks first as that is most common. You also need to make sure the fans are operating correctly.
You should change the thermostat after any overheat, as once they are run hot they become unreliable. Since manufacturers have started playing a new game of "hide the stuff you need to work on" It might not be at the engine end of the upper hose where it always was. Take a peek at a chiltons or haynes manual and you can find out where yours is.

temp switch is bad

U have a problem with the air temp control blend door actuator motor, very common failure. In order to replace this part the dash must come out.

Speedometer or fuel gage?

If speedometer which is bouncing around, it is likely a bad ground near where the speed sensor wire harness (which connects the speed sensor to the rest of the "network") exits the transmission housing. It's at the very back of the transmission (you have a 4T60E trans) to the left of where the right side half-shaft leaves the trans housing. Just look for damaged wires. If none, replace the speed sensor for $50-60.

If it is the fuel gage, the sensor is probably not "zeroed"--it's reading wrong, too high, and if it were to start at true "empty", it would read right. Thus, the gage is always reading a little high (maybe a 1/8-1/10th of a tank too high?). This isn't a problem until to stop, start, or turn quickly and cause the fule to slosh around in the tank and starve the in-tank pickup which sends fuel to the engine.

If it is the fuel gage, you should simply put as much fuel in as you can and see if the needle goes far above "F". If it does, note how far it went and then practice filling the tank when the needle is that same distance above "E".

Hope this helps.