Okay, now cooling prob is back, what do I do!

[Rob]

Sorry to bother you guys.

My car has some across a new problem. The cooling. Okay it has had it's cooling go wrong before, but it seemed to sort it self out, for a week I think, lol. Anyway. If i idle the car in trafic or anywhere for no more then 3 - 10 seconds, or driving below 20Km/s she will start to get hot and go into the red band area. But if I am driving along, the temp will stay half way, where it should be! I have now stopped using the car because of this.

Now, I don't know a lot about the cooling on this car. However I am guessing it's one of two things.

1. Trappened air in the system somewhere.
2. Stuck or stickky thermostat?

I'm thinking it's the latter. Can anyone point me in the right direction here. Oh while I was driving, I got a COOLANT TEMP. warning on my display.

Please someone help me here!

Thanks so much!

[JD525IA]

I know it's not the fan clutch because I pulled over, opened the hood, and watched the fan while I turned off the engine. The fan immediately stopped. This tells me the clutch is ok. Last year, I had similiar symptoms but the fan would spin when the engine was turned off, telling me the clutch needed replacement. My water pump is only 6 months old so I can write that off.

It was about 100 deg F late yesterday (Arizona), but I was surprised when the Coolant Temp came on.

I took her home and let it cool down a while. I added about 3 liters of 50/50 coolant mix and bled it. This morning, it was fine and when I came to a stop, the needle was in the middle. I wll see this afternoon when it gets warm outside.

I checked the Bentley manual, but it didn't really tell how to troubleshoot a bad thermostat. I have a feeling that mine is probably bad.

Good luck.

JD

[Rob]

I have a funny feeling my fan is stuffed. Will have to drive the car again to get home. But I think my A/C need refilling. Will this cause the fan not to come on?

Will check it when I get home.

Thanks.

Good luck to you too.

[joshua43214]

Needless to say, verify it is properly bled.

If the car maintains proper temperature when moving but over heats while stoped, the problem will probably not be the T-stat. The T-stat can break and cause it to not open enough or get lazy and not open enough, but usualy it will take a bit longer before the car will over heat. Save the T-stat opetion for last.

Most likely it is insufficient air flow through the radiator. Verify the thermoclutch on the fan is operating. Easy test, let the car get to about 2/3 on the temp gauge, rev the engine up, if the fan is engage it will et very load and blow alot of air. It will then slow down instantly to match engine speed when you let off the throttle.

Clear any debris from the front of the radiator and check for debris between the condensor and the radiator. If the fan is good and there is no debris, let it get to about 2/3 gauge again and spray a hose into the front of the radiator(good idea to cover the ignition wires for this). If spraying the radiator down with water does not bring the temp down, the radiator itself is most likely bad. If you have a high volume fan, you can put it front of the radiator instead of using water.

Also, the high speed circuit on the auxiliary fan should come when it gets very hot, so you may have a secondary problem there, but the thermo fan should maintain safe temps until the ambiant air gets up to about 100F.

Low freon will have no effect on cooling.

[JonE]

Summary on the two fans:
1. Auxiallary fan (the electric one in front of the radiator), comes on when the AC button is pushed. This fan also may come on in overheating conditions.
2. Fan clutch fan (the one behind the radiator, just ahead of the engine). As stated above, if that clutch is bad then you get your symptoms of overheating when idling or in slow traffic. Then all is good when rolling down the road.
I suspect the fan clutch first, that fan should blow alot of air around under the hood when the engine is warmed up or hot and usually comes to an abrupt stop when engine shut off. If engine is hot and fan spins, doesn't blow alot of air, and you shut off the engine and the fan just keeps spinning, then it likely is shot.
Removing the clutch is usually not too bad, need a large open end wrench, like a bycycle wrench, maybe 32mm (someone else may confirm this) and the nut is attached opposite of most threads. Rather than lefty loosey, this one will be righty loosey.

[Rustam]

I know it's not the fan clutch because I pulled over, opened the hood, and watched the fan while I turned off the engine. The fan immediately stopped. This tells me the clutch is ok. Last year, I had similiar symptoms but the fan would spin when the engine was turned off, telling me the clutch needed replacement. My water pump is only 6 months old so I can write that off.

It was about 100 deg F late yesterday (Arizona), but I was surprised when the Coolant Temp came on.

I took her home and let it cool down a while. I added about 3 liters of 50/50 coolant mix and bled it. This morning, it was fine and when I came to a stop, the needle was in the middle. I wll see this afternoon when it gets warm outside.

I checked the Bentley manual, but it didn't really tell how to troubleshoot a bad thermostat. I have a feeling that mine is probably bad.

Good luck.

JD

Troubleshooting the thermostat is simple - place it into a bowl with water and heat up. water boils at 212F whereas your theromstat opens between 180-190F...
You can place a thermometer in to observe the temperature when it starts opening...

[Felixdacat]

I just noticed in a current thred, that BMW coolant is highly recomended. Does it really matter what type coolant we use in our cars? Also my gauge sits halfway when warm all the time. Is this not good for the motor?

[Blitzkrieg Bob]

are bad for the headgasket and the mixed metals.

The only for sure coolant is the BMW Blue. there is a Zerex product, but I can't find here when I needed it.

Your guage needle should be at 12 O'clock during operating temp. 1 O'colck to 2 is trouble

[Felixdacat]

Thanks Blitz,
What type of Zerex are you looking for, and is is safe for all E34's? I have seen several Zerex products here where I live. Maybe I can find it here.
Thanks again.....Derek

[Blitzkrieg Bob]

are using the G-05 or G-48, but I just gave in and used the BMW stuff.