Overheating.

[Pccoxe]

I have a 85 BMW 325e that is overheating. I have replaced the radiator, water pump, coolant reservoir level sensor, and thermostat this week and it still over heats. I don't know what to do next. Any help?

[Elvir]

How you established symptoms of overheating? On cluster ?

[superj]

when does it overheat? while driving, while idling or slow speeds, or all the time? each time is a sign of a different part failing.

while driving only is a clogged radiator, generally
while idling or slow speeds is generally a fan clutch or fan switches
if all the time its usually a water pump, thermostat, or head gasket

[Pccoxe]

It was overheating when I was idling the car to bleed off the air from filling the new radiator up with 50/50 coolant. The fan clutch is only three years old. Do you think it was messed up from when the water pump failed and cause the first overheating issue? Also, do you think my sensor are bad?
I haven't driven it yet so I don't know if it will over heat while driving.

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I haven't driven it yet because it was overheating when I was filling the radiator with coolant and bleeding off the air.

[superj]

it will get hot while bleeding it so you should try and drive it but first, how bad an overheat did you have originally? like the car shut off from being so hot or was making crazy horrible noise? or you just saw it in the red and turned it off?

[Pccoxe]

The car would go into the red then it would slowly cool down into the 3/4 mark then jump back up. When I checked the engine, their was a white substance crushing the hoses and fan clutch and the water pump was wet. I knew that the water pump needed to be changed and I change the thermostat out. Then it still would over heat and I took it to a mechanic and he thought it was my radiator. So I change it yesterday and it was overheating when I was bleeding it out. When it was idling during bleeding it go to the red square but it never crossed into the square. It would slowly cool down to the 3/4 mark again. When it was overheating there wouldn't be a noise and the car never shut off. Does this information help you?

[Pccoxe]

By the way, I establish overheating using my instrument cluster. Is there a different way? Also is this the proper way?

[superj]

When you drive, the temp stays good? If you push the ac button and the electric fan comes on does the temp go down?

I use the cluster temp gage also. Since it never actually seems to have overheated, you should be ok. Does your fan clutch work? Like if you roll a piece of newspaper up and try and stop the fan, does it stop fast or feels strong and tries to keep turning?

It sounds like you still have air in it

[thejlevie]

A single trip into the red can warp the head and result in air being pumped into the cooling system. That air can interfere with coolant flow and cause the engine to run hot. A simple test for a head gasket problem is to allow the engine to get stone cold, then open the cap to relieve any pressure, and drive the car a bit. The hoses will be soft with no pressure in the system. Don't let it overheat while driving. Then allow the engine to get stone cold and see if the hoses are hard. If they are, air is being pumped into the cooling system.

[Pccoxe]

@thejlevie: do I take the drive with the cap off or do I put the cap on before I drive?

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@superj: when I turn the ac on the aux fan doesn't come on. My ac doesn't work period, it doesn't get cool at all, but I charged it awhile ago and it read that it was full of freon. I think my compressor and ac cooler is bad. Would that affect my cooling system?

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@superj: I haven't tried that fan test. I will tonight and report back tomorrow. Thank you all so far for your help.

[Elvir]

By the way, I establish overheating using my instrument cluster. Is there a different way? Also is this the proper way?

On old E30s, sometimes you must check temperature with some hand tool thermometer because cluster temperature gauge can be "shaggy".

[superj]

no, the ac not working won't hurt your cooling. other than you no longer have an electric fan on the front to use like a radiator fan. I use mine like that since my compressor is bad. I have the same problem, vacuumed out the system and filled everything and the compressor clutch locks up but no cold air, so compressor is bad, according to trouble shooting charts.

also, they sell a kit at the local auto parts store that you can put a strip of paper into your coolant and if it turns a certain color, your head gasket is leaking, if the other test is hard to gage. just ask the guy at the counter

[Pccoxe]

Thank you all for your help. I checked my radiator temp and the hoses to see if the car is overheating. It is not. My sensor in my instrument cluster is faulty and measuring high. I have to change it. I again wanted to thank you all for your guidance. If the future, I will hopefully come to you all for a better understanding of this car. I have been working on this car here and there since I was 15. Now that I have a full time job, I can really start to fix it up to where is should be. I know I'm a novice to this car but one day I hope to be more knowledgeable like you all. Thank you again

[Elvir]

Thank you all for your help. I checked my radiator temp and the hoses to see if the car is overheating. It is not. My sensor in my instrument cluster is faulty and measuring high. I have to change it. I again wanted to thank you all for your guidance. If the future, I will hopefully come to you all for a better understanding of this car. I have been working on this car here and there since I was 15. Now that I have a full time job, I can really start to fix it up to where is should be. I know I'm a novice to this car but one day I hope to be more knowledgeable like you all. Thank you again

For start try to tight 7mm nut on cluster temperature gauge.

[CosmoUrs4]

Hey bud, we all start somewhere. Keep adding to your tool collection as you go. Proceed with caution on all you projects and make sure all connections are tight before firing her up.

[superj]

Pccoxe, how did it go? did tightening that little brass nut help any?