What can it be? Please help, urgent now.

[genphreak]

No, the 525i's don't have that line going to the Rad tank. Wish it was that simple. Thanks for the help anyway. Appericated!

Yes the overflow tank is on the side on a 525. Some people use a pencil with the fan, its not a terribly reliable test and risky so I think the paper sounds the best approach to get a rough idea. The clutches do need to be changed, I renewed mine as it had never been done, but the old one was just fine anyway. Make sure you bled the car properly, ie by doing it first when cold and not running; just by letting the fluid through the bleeder until it spits only clear coolant. That's how it is on the M30 with the overflow tank above the motor- so check the reccommended procedure for your motor is- a lot of peeps on here are confused about bleeding, best to go by the Bently Rob.

[Rob]

Hi there,

Okay, will do the test later tonight. I'm not sure I am 100% up to bleeding the car. You see, my consern is the engine running while I'm bleeding it. She will just overheat while I'm doing it. I am far too worried about the headgasket going and stopped using the car until problem is fixed. I've read many bleeding guides. And the say turn heating controls up and fan on. However that fan doesn't really make a difference. What do you suggest I do?

[Rob]

Okay, decided. Here's my plan of attack on this lovely car this weekend.

1. Test fan and clutch
2. Drain whole cooling system.
3. Go buy new coolant. At the moment it's just water in the system, no Coolant at all.
4. Re fill cooling system with 50 water 50 coolant.
5. Bleeed system,
6. Clean Coolant Sensor.
7. Hope and pray that the Head Gasket is still in tacked.

Does this sound like a good plan of attack on this problem?

If the H.G is blowen, I might as well look at a new car.

[632 Regal]

test the auxillary fans in front of the radiator by turning the AC on, the fans should come right on. you can see them through the front grill. If not track the problem, if they do then the thermo switch or relay could be bad, one step at a time.

REPLACE your clutch right away, if it was good it shouldnt heat up, since it cools down at speed im guessing the radiator isnt clogged. Im not one for sticking my arm into spinning things myself but whatever floats your boat. Much easier than replacing a headgasket.

[Rob]

Jeff, my A/C needs refilling. So that fan doesn't come on.

[632 Regal]

it should run when it gets hot though.

Jeff, my A/C needs refilling. So that fan doesn't come on.

use distilled water when you change the coolant.

[Rob]

Oh okay. Now if that fan isn't working....would this definitely cause the problem, or only make the car run a little hot when engine compartment gets hot? Or will it overheat?

I'm pretty sure it isn't working. Anyway I can jumper it so thus testing fan and switch?

Thanks a lot for the help, Jeff. Apperceiate it!

[Alexlind123]

The main fan should provide "viscous resistance" when turning it with the engine off.

[Javier]

the sensor connector in the radiator. It's a three pole connector, jump the pins in pairs, one pair selection does nothing and will do no harm to jump them, the other two jumping possibilities turn on low speed and high speed.

You need the water inside the radiator to be hot to turn on the auxiliary fan (I mean, if pump is not pumping, or tstat is not opening, water in radiator is cool no mater the engine is overheated, and fan will not turn on). You can also test the temperature sensor with a boiling water pan and a cooking thermometer, below is a picture of the sensor internals. you can hook a continuity tester to the pins and wait for water to reach 91 and 99 degrees C to close the contacts (you will not reach 99 if above sea level so will have to switch to boiling oil instead). If failed, replace the sensor.

Fan clutch need to work to have things running normal. It will avoid over stressing the auxiliary fan and engine temperature. (as you see, fan engages only when things are turning hot (91-99).

Javier

[joshua43214]

The engine fan has a viscouse clutch in it, this allows the fan to rotate with the engine at all times, but not run at engine speed unless it becomes hot enough to engage. This is mostly done so you wont waste energy running a fan that is not needed.

When the fan engages, it will turn with the engine with no slipage. When you rev the engine, it will instantly speed up, and instantly slow down on decel. when you stop the engine, it will instantly stop. The fan should engage at just about the 1/2 gauge point and will cycle on and off with the thermostat. T-stat opens,blast of hot air heats the fan clutch and it engages. T-stat closes, clutch cools off and disengages.

Any of the above methods will work for testing the clutch, but if you rev the engine with the fan clutch engaged, you will have no doubt it working since you get a loud roaring blast of hot air that will make you feel faint on a very hot day.

The aux fan should also come on at higher temp, I think about 2/3 gauge. It will come on and will remain on until the engine as back to normal temperature.

If the coolant level is good and you still get the low coolant warning, the sensor is most likely bad, they fail very commonly, and are cheap. just replace it if it is suspect.

Another sign of a bad fan clutch is it being dirty. The oil will leak out of the clutch and coat the fins and then collect dust. The clutch should be the color of a normal dusty old part. if it has the black color that parts get when they have old oil combined with dirt, it is bad.