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Discussion Starter #1
Hello,

I've got a 01 330xi (M54) that is running hot. I have an OBDII Scanner and OBD Fusion application. I just installed a brand new radiator and Upper and Lower hoses (Gates) and have probably used 10 gallons of antifreeze trying to keep it cooled down enough so I don't ruin the engine. It has 183,000 miles on it and I am very pro preventative maintenance. I use Mobil One 0/40 and Mann filters and change the oil every 6,000 miles. Normally the coolant temperature runs at 200 degrees but overheats when I'm stopped at lights and will spike from anywhere from 210-220 degrees but when I am driving 70mph the temperature drops back down to 200 degrees which is normal. I had a mechanic run a pressure test on it and we don't appear to have any leaks. I'm pretty sure it's not the water pump. I did buy a new radiator cap today as the rubber seals were worn out on the old one and I am losing fluid from somewhere! I'm starting to think it may be the thermostat at this point and I just ordered one that will be here in a few days but I wanted to put it out here on the forum and see what helpful advice I can get. Right now I'm just keeping it topped off and I've never had the needle go over into the red since we put the new radiator in however it's costing me a lot of $$$ in antifreeze while I am trying to get a resolution to the issue. Thanks! :banghead:
 

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Sounds like the fan to me. If it overheats at idle, the fan isn't running (most likely). The fan doesn't do much while driving which is why it doesn't overheat then
But if you're losing coolant, I'd do a leakdown test
 

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Discussion Starter #3
Fan is running fine

I did check the fan. It runs fine! I checked it yesterday when I got out of the car and popped the hood and I actually heard the fan speed up so I don't think that's it. Not impossible but that's what I observed.
 

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I did check the fan. It runs fine! I checked it yesterday when I got out of the car and popped the hood and I actually heard the fan speed up so I don't think that's it. Not impossible but that's what I observed.
Which fan (if the car's auto)? The one attached to the engine or the one in front?
 

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Discussion Starter #5
Both are running. The one in front is the one that I could hear speeding up which is what it is supposed to do when it gets hot. I live in South Florida so it's 92+ everyday here. Especially at this time of year!
 

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Both are running. The one in front is the one that I could hear speeding up which is what it is supposed to do when it gets hot. I live in South Florida so it's 92+ everyday here. Especially at this time of year!
Okay at this point, it may not be spinning fast enough or a warped head. Unplug the lower coolant temp sensor (only the plug and not the actual sensor) and see if that helps the overheating situation at idle at all
 

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Discussion Starter #7
Are you referring to the sensor that sits on the bottom of the expansion tank? Here's the thing I haven't mentioned yet, I had a guy who is a mobile mechanic swap out the radiator and I asked him what the spring was that fell on the ground when he was taking the old out. This is why I keep coming back to the thermostat. I'm not a mechanic but rather a network engineer so I'm trying to apply common sense principles to this issue. I'm just going to ask at this point if there's anybody either in West Palm Beach, Fort Lauderdale or Miami who'd be willing to take a look at this for me. I'm based in Ft. Lauderdale but I work in all of these cities and I'm working in each one of them at least once a week so it's no problem for me to take it almost anywhere in South Florida. I'm just not going to take it to a BMW dealer because they'll charge me more then the car is worth!
 

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Are you referring to the sensor that sits on the bottom of the expansion tank? Here's the thing I haven't mentioned yet, I had a guy who is a mobile mechanic swap out the radiator and I asked him what the spring was that fell on the ground when he was taking the old out. This is why I keep coming back to the thermostat. I'm not a mechanic but rather a network engineer so I'm trying to apply common sense principles to this issue. I'm just going to ask at this point if there's anybody either in West Palm Beach, Fort Lauderdale or Miami who'd be willing to take a look at this for me. I'm based in Ft. Lauderdale but I work in all of these cities and I'm working in each one of them at least once a week so it's no problem for me to take it almost anywhere in South Florida. I'm just not going to take it to a BMW dealer because they'll charge me more then the car is worth!
Nope. that sensor at the bottom of the expansion tank is for the fluid level. The sensor I'm referring to goes into the lower radiator hose.

When he took off the radiator and a spring fell off, I doubt that was the thermostat spring. Maybe it was the auto transmission cooler thermostat which isn't a big deal. If you have a picture of it that would be great
 

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Discussion Starter #9
You make a really good point here. He told me he didn't think that spring was a big deal either. What I'm strongly starting to believe is that it's the lower coolant hose is where I'm losing all the fluid. I haven't had this car up on a lift yet because I haven't had access to one but that much fluid has to be coming from there and maybe the lower hose wasn't put on correctly? I wasn't there when that was supposedly done so it's possible it wasn't changed out at all.
 

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You make a really good point here. He told me he didn't think that spring was a big deal either. What I'm strongly starting to believe is that it's the lower coolant hose is where I'm losing all the fluid. I haven't had this car up on a lift yet because I haven't had access to one but that much fluid has to be coming from there and maybe the lower hose wasn't put on correctly? I wasn't there when that was supposedly done so it's possible it wasn't changed out at all.
A very common issue is the o-ring that leaks for that sensor. Usually when swapping hoses, the same o-ring gets reused and it leaks. Here's the part number 13621743299
 

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Let’s start with some questions:
1. Have you scanned the engine computer (DME) for codes?
2. Has the cooling system been overhauled?
3. Are you properly bleeding the cooling system?
4. What brands of parts are you putting the cooling system?
5. How old is the water pump?
6. Have you checked the thermally activated clutch on the fan on the water pump (I’m assuming the car has an automatic transmission)?
7. Have the block’s cooling channels been flushed in the direction opposite to the normal flow?

The fact that the temperature goes up while the car is being driven at 70mph tells me there’s a coolant flow problem. Why? It takes 4x the energy when doubling the speed. That is, ignoring aerodynamics, driving at 70mph requires 4x as much energy as driving at 35mph. Heat is a form of energy.
 

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Let’s start with some questions:
1. Have you scanned the engine computer (DME) for codes?
2. Has the cooling system been overhauled?
3. Are you properly bleeding the cooling system?
4. What brands of parts are you putting the cooling system?
5. How old is the water pump?
6. Have you checked the thermally activated clutch on the fan on the water pump (I’m assuming the car has an automatic transmission)?
7. Have the block’s cooling channels been flushed in the direction opposite to the normal flow?

The fact that the temperature goes up while the car is being driven at 70mph tells me there’s a coolant flow problem. Why? It takes 4x the energy when doubling the speed. That is, ignoring aerodynamics, driving at 70mph requires 4x as much energy as driving at 35mph. Heat is a form of energy.
The temperature goes up when stopped and back to normal when driving
 

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Op that sounds like a fan problem. See if you can stop your fan clutch with a newspaper or a piece of cardboard
Fan clutch won't prevent overheating whether or not it's functioning (to a certain degree)
 

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Discussion Starter #16
In answer to markusmarkus questions:

Originally Posted by markusmarkus View Post
Let’s start with some questions:
1. Have you scanned the engine computer (DME) for codes? (Yes, no codes returned)
2. Has the cooling system been overhauled? (Do not know that) It has a new radiator!
3. Are you properly bleeding the cooling system? (Yes)
4. What brands of parts are you putting the cooling system? (Gates)
5. How old is the water pump? (Don't know that)
6. Have you checked the thermally activated clutch on the fan on the water pump (I’m assuming the car has an automatic transmission)? (Yes it's an automatic and I don't even know how to do that)
7. Have the block’s cooling channels been flushed in the direction opposite to the normal flow? (Don't know how to do that)

I'll ask again, are any of you in South Florida? Is anybody who has read this thread live in South Florida)

Thanks!
 

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Stop the big leak first! If it lost that much coolant, means there was not enough build up pressure to prevent boiling, and coolant heat transfer efficiency was down.
 

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Op that sounds like a fan problem. See if you can stop your fan clutch with a newspaper or a piece of cardboard
No. Even without the clutch fan the working electric fan will keep the engine from overheated.
Really? I tested this theory a while ago and the aux is not really enough to cool the car Especially in the summer heat. I***8217;m sure op has the ac on too which will add to the heat.

Ops car is overheating when stopped and not when moving, first thing needs to be checked is the fan. Second is the water pump. I'm betting it's not bled properly as well.

Op see if you can stop ur fan with little effort. I***8217;m betting it***8217;s trash. Also check out your water pump.
 

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Really? I tested this theory a while ago and the aux is not really enough to cool the car Especially in the summer heat. I***8217;m sure op has the ac on too which will add to the heat.

Ops car is overheating when stopped and not when moving, first thing needs to be checked is the fan. Second is the water pump. I'm betting it's not bled properly as well.

Op see if you can stop ur fan with little effort. I***8217;m betting it***8217;s trash. Also check out your water pump.
when I was doing my cooling system refresh, I didn't reinstall my clutch fan so that I could see if there were any leaks. The aux fan did just fine cooling the car in 100°F+ weather
 
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