318ti engine overheating ?

[jimmymcmahon]

Hi guys,

Its been snowing a lot over the past few days and consequentally I have been stuck in traffic queues continually stop starting...

this has caused the indicator (Shown below) on the dash board to go into the red zone on a number of occasions......


This happened to me when i first bought the car off my relative ...there was no snow, but we were stuck in a traffic jam for a good 50 minutes...but as soon as we started moving again and picked up speed the temperature dropped to normal..

Is this normal behaviour in cold weather? I have just topped up the coolant this morning..however I still went into the red temporarily on my way to work..
.
Any help would be appreciated.

Cheers guys
Jimmy

[spidertri]

Correct behavior is for the needle to be right in the middle of the gauge. It should never go past center. These cars do not like having the temperature anywhere near the red, having the needle in the red for more than a minute can cause the headgasket to fail and the head to warp. Big bucks for that repair.

Was there any coolant in the radiator when you topped it up? Was there oil mixed in with it? Check your engine oil for coolant as well.

[cooljess76]

http://www.318ti.org/forum/showthread.php?t=27983

[jimmymcmahon]

Originally Posted by spidertri

Correct behavior is for the needle to be right in the middle of the gauge. It should never go past center. These cars do not like having the temperature anywhere near the red, having the needle in the red for more than a minute can cause the headgasket to fail and the head to warp. Big bucks for that repair.

Was there any coolant in the radiator when you topped it up? Was there oil mixed in with it? Check your engine oil for coolant as well.

Thanks for the reply mate.

Am i correct in thinking the correct level it should be at (when the engine has rested)..is at the thick marker about halfway up the coolant holder? or should i fill it past this?

It appeared to be well below this mark before I filled it

[spidertri]

Coolant level should be at the "COLD/KALT" line on the expansion tank, I'm pretty sure that is what you are talking about. If you follow the instructions in the link cooljess posted (and you should) the level will be at that line.

You should definitely pull the dipstick and check the oil to make sure it is the normal color.

[pnosker]

Since it has to do with movement, try turning the AC on when you're stopped to trigger the AC fan. That might help at least for the short term.

[Bills86e]

The cooling system will not operate with an air bubble in it.
COOLJESS pointed me in the right direction as Tilt NOSE Up,
Squeeze hose, up to middle temp, bleed, coolant to mid of
see-thu expansion tank. THANKS COOLJESS
Now with Air bubble gone, system works perfectly!

[mohaughn]

Just want to point out that if you have an air bubble in the system the car will always overheat, regardless if the car is moving or not. So if your problem is that the car only overheats when you are in traffic, I would guess that your radiator fan is not working.

When it starts to overheat, does the temp come down as soon as the car starts to move? If so, it is overheating due to lack of air movement through the radiator. Have to check the fan temp switch as well as the fan itself. Also, if you have an air bubble in the cooling system, you can hear the coolant bubbling in the system. It will actually overpressurize and blow coolant everywhere.

Just changed my hoses last week and had a bear of a time bleeding the system, and based on what the OP posted, doesn't sound like an air bleeding issue to me.

[cooljess76]

Does the heater blow hot air? Does the fan come on when you turn on the A/C?

[MPWR]

Bad bad bad bad bad....

It is not ever normal for a BMW to run hot, no matter the weather. Letting a ti overheat just once usually results in significant engine damage. The head gasket usually blows, and often the cylinder head is bent from the heat.

When you went to refill coolant, you cold see a little in the bottom of the plastic tank? I'm guessing you have a major coolant leak, and that is why the engine overheats. If so you can add coolant and bleed all day long, but you still have real troubles.

Do you change your own oil? The real question now is if you have coolant in your oil system (sure sign of a headgasket failure).

[6speed ti]

Quick things to check.

Coolant level when cold.
Fan turning on when temp rises in radiator.
You can see if the fan works by turning on the A/C. This only verifies that the fan motor is working not the radiator temp sensor.
Fan will run normal speed then will go to high speed if temp continues to rise.
Since the temp recovers when you move at higher speeds you can eliminate the thermostat.
Air trapped in the system will cause you to overheat.
Do this procedure to eliminate air pockets in the cooling system.
When the engine is cold drain the coolant out of the radiator ONLY into a clean container. You will reuse it again. Next open the black bleeder screw next to the
radiator cap. Then remove the radiator cap and fill the radiator until coolant comes out of the bleeder. This will ensure you have removed or bled out all air bubbles from the radiator. Do this step with the engine OFF!! Do not run the engine while filling up the radiator. This will induce air back in the system.
You can also try turning on the A/C when the coolant indicator starts to rise past the mid way mark. If the temp drops back to normal then you have an issue with the temp sensor on the radiator. If it does not, get out of the car and verify if the fan is running.
If the fan is running then you might have a blocked or clogged radiator. Another possibility is that you may have a water pump with the so called plastic type impeller. They have been known to loosen from the shaft and not spin at the same speed as the shaft. This makes sense at lower speeds the impeller is virtually not turning but at higher speeds it spins enough to circulate the coolant in addition to the ram air at higher speeds. One more thing I forgot to mention, on the sensor for the radiator which is mounted on the left side of the radiator check the circuit to eliminate wiring problems. You will see three wires on the connector. The BROWN wire is your common ground. Use a jumper wire from one of the other wires to the BROWN one. One wire is for normal speed and the other is for high speed. If the fan does not kick on or only in normal or high then you may have to look at the fan relay. I am not going into that for now. Way too much info here for now.

I know I gave you a big to do list, but check the easy stuff first.
Remember to keep it simple first. Good luck.

[jimmymcmahon]

Originally Posted by 6speed ti

Quick things to check.

Coolant level when cold.
Fan turning on when temp rises in radiator.
You can see if the fan works by turning on the A/C. This only verifies that the fan motor is working not the radiator temp sensor.
Fan will run normal speed then will go to high speed if temp continues to rise.
Since the temp recovers when you move at higher speeds you can eliminate the thermostat.
Air trapped in the system will cause you to overheat.
Do this procedure to eliminate air pockets in the cooling system.
When the engine is cold drain the coolant out of the radiator ONLY into a clean container. You will reuse it again. Next open the black bleeder screw next to the
radiator cap. Then remove the radiator cap and fill the radiator until coolant comes out of the bleeder. This will ensure you have removed or bled out all air bubbles from the radiator. Do this step with the engine OFF!! Do not run the engine while filling up the radiator. This will induce air back in the system.
You can also try turning on the A/C when the coolant indicator starts to rise past the mid way mark. If the temp drops back to normal then you have an issue with the temp sensor on the radiator. If it does not, get out of the car and verify if the fan is running.
If the fan is running then you might have a blocked or clogged radiator. Another possibility is that you may have a water pump with the so called plastic type impeller. They have been known to loosen from the shaft and not spin at the same speed as the shaft. This makes sense at lower speeds the impeller is virtually not turning but at higher speeds it spins enough to circulate the coolant in addition to the ram air at higher speeds. One more thing I forgot to mention, on the sensor for the radiator which is mounted on the left side of the radiator check the circuit to eliminate wiring problems. You will see three wires on the connector. The BROWN wire is your common ground. Use a jumper wire from one of the other wires to the BROWN one. One wire is for normal speed and the other is for high speed. If the fan does not kick on or only in normal or high then you may have to look at the fan relay. I am not going into that for now. Way too much info here for now.

I know I gave you a big to do list, but check the easy stuff first.
Remember to keep it simple first. Good luck.

really appreciate all your help guys,

I just picked it up from the garage yesterday...the problem was the thermostat housing / casing and pipe were leaking....so coolant was not getting to the engine...apparently? either way..they have replaced the thermostat housing and pipe and all is now well....im getting hot and cold air as expected!

[Bills86e]

Not really! We would all like to know how the relay turns on
each speed, ans how to ensure it works properly. More info!

[6speed ti]

Originally Posted by Bills86e

Not really! We would all like to know how the relay turns on
each speed, ans how to ensure it works properly. More info!

OK here is the short version to your question. There is a temp switch also known as a thermo switch. It is a dual temp switch. This switch is located on the right side of the radiator. The connector consists of three wires. A common ground and two feeds. When the temp reaches a predetermined level it closes the switch and turns on the fan. This will be the normal speed. If the temp continues to rise to the next trigger level then it will activate the fan to the High speed. It also gets a input from the A/C when turned on. This input puts the fan at the normal speed as well. You can check the circuit by jumping the ground wire (BROWN COLOR) to one of the other wires. This will turn on the fan at either speed depending which wire you jumped to ground. Remember to have the ignition switch at the run position. Engine does not have to be running. If this troubleshooting method passes you can assume that the temp switch is bad. You can simply check the fan motor by turning on the A/C and it should turn on.

That's the short version. Hope this answered your question. Remember to never drive your car when the engine is running HOT in the red zone. The M44/M43 engines are All Aluminum. Instant destruction!