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**cooljess76** · 05-19-2010, 02:27 AM

Hey Dro, yeah that's funny about the panther edition thing. Definitely not a BMW thing. Anyway, it sounds like you have a couple issues keeping your car from running it's best. The first thing I'd address is the overheating problem. The cooling system is the weak link on our cars. It has many plastic components that tend to fail after 100-150k miles. It's a really good idea to replace the entire cooling system at this point if it hasn't been replaced already. The whole system including radiator can be replaced over a weekend for under 400 bucks. This would include the radiator, radiator cap, hoses, water pump, thermostat, plastic coolant fittings, a couple gallons of coolant and perhaps a temp sensor. Now I understand your financial situation might not permit you to do this all at once, but as soon as you get a chance, you should probably make an effort to get things swapped. Here's a really good writeup for replacing the cooling system:
http://www.318ti.org/forum/showthread.php?t=18066

Now, before we jump the gun, lets try to figure out why your car was overheating in the first place. You say you removed the thermostat and are currently running without one. That's fine as a temporary fix since you live in FL and the weather is warm. However long term effects will be bad for your motor. You can check your thermostat by placing it in a pot of water on the stove with a thermometer and watching the thermostat physically open when the thermometer reaches the temperature marked on the thermostat. However, since you'll probably be rebuilding your cooling system soon anyway, you might just want to go ahead and purchase a new thermostat. You can find the part#'s on realoem.com. Just type in the last 7 digits of your vin, it'll give you a complete list of parts and diagrams, find your part and the corresponding part#. Two of my favorite sites for online shopping for BMW parts are pelicanparts.com and getbmwparts.com. Both places offer great service, reasonable prices and fast shipping.

The fan really doesn't come on very often unless somethings wrong. Maybe if you're stopped in traffic and the outside temp is over 100 degrees, but the only time I've ever seen one of these fans kick on is when you turn on the A/C. I've seen cars that will strain electrically monentarily when the fan kicks on. This may have been what killed your alternator which then killed your battery. Afterall, you did say you rigged the fan to stay on full time. So what caused the car to overheat? I doubt it was the fan, it's really not needed unless there's a problem and even then I've seen cars overheat and the fan never kicked on. One thing that I know occurs is that over time, our cooling systems trap air in the radiator resulting in whats called air-lock. Basically your radiator develops an air bubble which prevents the coolant from circulating through the engine, then the coolant evaporates since it can't circulate which creates an even larger air bubble and then the overheating begins. Before we go any further, let me make this very clear, IT"S NEVER OK TO OVERHEAT THESE ENGINES! Not even for a few seconds. A few seconds in the red almost always results in a blown head gasket. If not right then, it still can cause permanent damage to the gasket due to fatigue which will substantually reduce the life of the gasket. So if you ever notice the needle moving past 12 o'clock, SHUT THE CAR OFF IMMEDIATELY. I don't care if your house is only a couple blocks away. Failure to do so will end up costing you $2000 in a head gasket job, possibly a warped or cracked head or even ruined engine. You can tell if you have an air-locked cooling system by turning the heater on. If you don't get hot air(and I mean REALLY HOT air), then you probably have air in the system which needs to be bled asap. Here's a writeup on how to properly bleed the cooling system:
http://www.318ti.org/forum/showthread.php?t=27983

So lets say the system is bled, but you still have an overheating issue. Well we know it's not the thermostat, because you don't have one. Get one. And whenever you open the loop, allowing coolant to drain out, such as replacing the thermostat or water pump, you cannot just top off the coolant in the expansion tank and call it good. The reason why is because there's now an air pocket in your engine which will eventually make it's way into the radiator. So you need to bleed the system while you're topping it off. This may take several attempts to complete successfully.

Your next culprit is the water pump. Water pumps are a relatively simple design and fail in one of two ways. Either the bearing wears out and causes it to leak or seize. This usually can be noted by a squeaking sound from the pump itself or a chirping sound from the belt tensioner. I believe the tensioner has a built in chirping mechanism designed to chirp when there's an irregular resistance in the belt drive. The other means of failure would be a broken impellar. Older style water pumps had a plastic impellar which was know to shatter leaving bits of plastic in your engine block and cooling system. The newer pumps come with metal impellars. Beware of companies claiming to have new composite impellars. I think those are just people trying to sell off their old stock of plastic impellar pumps. Get one with a metal impellar. People will say they rust, that BS. They won't rust if you use distilled water mixed properly with the correct antifreeze.

So lets say you've bled the system repeatedly, replaced the thermostat and water pump, can't find any coolant leaks, but you still continue to loose coolant. You may have a small crack in your radiator. Our radiators have plastic expansion tanks that are known to crack at the seam where it mounts onto the aluminum part of the radiator. This seam is covered by a plastic shroud and the leak may be so small that the coolant evaporates before enough of it collects to drip on the ground or onto the plastic underpanel attached to the bumper. You can check your radiator and entire cooling system for that matter by pressurizing the system. You'll need to buy, rent, borrow or make a pressurizing tool. With the engine cool and off, pressurize the sytem to about 10psi. Don't go much further beyond that. Listen carefully for any hissing. If you hear a hiss, try to locate it. It might help to do this in a quiet garage. I found a hairline crack in my radiator using this method. If you hear a hiss towards the back of the motor, you likely have a cracked "Y" fitting. If you hear hissing under the intake manifold, you likely have a cracked coolant fitting on the side of the engine block. If you notice the carpet wet under the dash behind the center console, you likely have a cracked heater core. If you see coolant or perhaps a white residue under your water pump, you likely have a bad water pump or bad o-ring. Temp sensors don't fail often, if they do it's usually due to air-lock causing the coolant to evaporate and blowing extremely hot air across the sensor which damages the sensing element. Or it may have a broken or damaged wire.

So first thing, get your cooling system fixed. It's really important. I know, you can't fix the cooling system if the car doesn't run right. Right. So lets fix the electrical problem BEFORE YOU START DRIVING THE CAR with a bad cooling system. I mentioned earlier that your fan wiring might be the culprit. Return it back to stock. Did you say you got a new battery? If so, take your battery and alternator to your local auto parts store. Pep Boys, Advanced Auto, Oriley's, Auto Zone and Napa should have battery and alternator testing equipment. Most places will let you drop off your battery while they test it and charge it for free. If you want them to charge it, you have to ask them to, otherwise they'll just test it. They will also bench test your alternator right in front of you so you can see if it works or not. If it's bad, you can have your buddy rebuild it with new brushes, bearings and a voltage regulator. Or you can just buy a refurbished one. I get my alternators from this guy:
http://stores.ebay.com/id=144108571

So lets say your alternator and battery are both good. Now you want to check the output. Start by cleaning off the battery terminals and cables with a wire brush. Buy, rent, borrow a digital multimeter. With the engine running and all electrical components turned off(headlights, AC, radio etc), check the voltage across the two battery terminals. You should see close to 14v, maybe a little over 13v. Now check the output at the back of the alternator. Place the red lead from the multimeter on the larger terminal on the back of the alternator. Place the black lead on either the smaller stud or it's easier to just touch it against a bare piece of metal in the engine compartment such as one of the strut tower nuts. Again, you should see about 14v. If you notice it rising and then dropping in voltage, you may have a bad engine ground. Turn the car off and check underneath the car on the passenger's side just inward of the front wheel well. There will be a large gauge wire connecting the passenger side motor mount to the cassis. Go ahead and remove this wire, clean the ends with a wire brush as well as the surface on the chassis and motor mount where it makes contact. Hook it back up and tighten the bolt nice and tight. Now go back and check if you have a steady 13-14v. If som you fixed your problem. If not, you have a parasitic drain somewhere. You can take your car to Sears or an independant mechanic to diagnose the problem. This will save you money vs. going to the dealer. Sears will usually test your charging system for free.

05-19-2010, 02:27 AM	#3
cooljess76 NOBODY F's with the Jesus Join Date: Oct 2006 Location: Ventura California Posts: 7,824 iTrader: (6) Photo Gallery	Hey Dro, yeah that's funny about the panther edition thing. Definitely not a BMW thing. Anyway, it sounds like you have a couple issues keeping your car from running it's best. The first thing I'd address is the overheating problem. The cooling system is the weak link on our cars. It has many plastic components that tend to fail after 100-150k miles. It's a really good idea to replace the entire cooling system at this point if it hasn't been replaced already. The whole system including radiator can be replaced over a weekend for under 400 bucks. This would include the radiator, radiator cap, hoses, water pump, thermostat, plastic coolant fittings, a couple gallons of coolant and perhaps a temp sensor. Now I understand your financial situation might not permit you to do this all at once, but as soon as you get a chance, you should probably make an effort to get things swapped. Here's a really good writeup for replacing the cooling system: http://www.318ti.org/forum/showthread.php?t=18066 Now, before we jump the gun, lets try to figure out why your car was overheating in the first place. You say you removed the thermostat and are currently running without one. That's fine as a temporary fix since you live in FL and the weather is warm. However long term effects will be bad for your motor. You can check your thermostat by placing it in a pot of water on the stove with a thermometer and watching the thermostat physically open when the thermometer reaches the temperature marked on the thermostat. However, since you'll probably be rebuilding your cooling system soon anyway, you might just want to go ahead and purchase a new thermostat. You can find the part#'s on realoem.com. Just type in the last 7 digits of your vin, it'll give you a complete list of parts and diagrams, find your part and the corresponding part#. Two of my favorite sites for online shopping for BMW parts are pelicanparts.com and getbmwparts.com. Both places offer great service, reasonable prices and fast shipping. The fan really doesn't come on very often unless somethings wrong. Maybe if you're stopped in traffic and the outside temp is over 100 degrees, but the only time I've ever seen one of these fans kick on is when you turn on the A/C. I've seen cars that will strain electrically monentarily when the fan kicks on. This may have been what killed your alternator which then killed your battery. Afterall, you did say you rigged the fan to stay on full time. So what caused the car to overheat? I doubt it was the fan, it's really not needed unless there's a problem and even then I've seen cars overheat and the fan never kicked on. One thing that I know occurs is that over time, our cooling systems trap air in the radiator resulting in whats called air-lock. Basically your radiator develops an air bubble which prevents the coolant from circulating through the engine, then the coolant evaporates since it can't circulate which creates an even larger air bubble and then the overheating begins. Before we go any further, let me make this very clear, IT"S NEVER OK TO OVERHEAT THESE ENGINES! Not even for a few seconds. A few seconds in the red almost always results in a blown head gasket. If not right then, it still can cause permanent damage to the gasket due to fatigue which will substantually reduce the life of the gasket. So if you ever notice the needle moving past 12 o'clock, SHUT THE CAR OFF IMMEDIATELY. I don't care if your house is only a couple blocks away. Failure to do so will end up costing you $2000 in a head gasket job, possibly a warped or cracked head or even ruined engine. You can tell if you have an air-locked cooling system by turning the heater on. If you don't get hot air(and I mean REALLY HOT air), then you probably have air in the system which needs to be bled asap. Here's a writeup on how to properly bleed the cooling system: http://www.318ti.org/forum/showthread.php?t=27983 So lets say the system is bled, but you still have an overheating issue. Well we know it's not the thermostat, because you don't have one. Get one. And whenever you open the loop, allowing coolant to drain out, such as replacing the thermostat or water pump, you cannot just top off the coolant in the expansion tank and call it good. The reason why is because there's now an air pocket in your engine which will eventually make it's way into the radiator. So you need to bleed the system while you're topping it off. This may take several attempts to complete successfully. Your next culprit is the water pump. Water pumps are a relatively simple design and fail in one of two ways. Either the bearing wears out and causes it to leak or seize. This usually can be noted by a squeaking sound from the pump itself or a chirping sound from the belt tensioner. I believe the tensioner has a built in chirping mechanism designed to chirp when there's an irregular resistance in the belt drive. The other means of failure would be a broken impellar. Older style water pumps had a plastic impellar which was know to shatter leaving bits of plastic in your engine block and cooling system. The newer pumps come with metal impellars. Beware of companies claiming to have new composite impellars. I think those are just people trying to sell off their old stock of plastic impellar pumps. Get one with a metal impellar. People will say they rust, that BS. They won't rust if you use distilled water mixed properly with the correct antifreeze. So lets say you've bled the system repeatedly, replaced the thermostat and water pump, can't find any coolant leaks, but you still continue to loose coolant. You may have a small crack in your radiator. Our radiators have plastic expansion tanks that are known to crack at the seam where it mounts onto the aluminum part of the radiator. This seam is covered by a plastic shroud and the leak may be so small that the coolant evaporates before enough of it collects to drip on the ground or onto the plastic underpanel attached to the bumper. You can check your radiator and entire cooling system for that matter by pressurizing the system. You'll need to buy, rent, borrow or make a pressurizing tool. With the engine cool and off, pressurize the sytem to about 10psi. Don't go much further beyond that. Listen carefully for any hissing. If you hear a hiss, try to locate it. It might help to do this in a quiet garage. I found a hairline crack in my radiator using this method. If you hear a hiss towards the back of the motor, you likely have a cracked "Y" fitting. If you hear hissing under the intake manifold, you likely have a cracked coolant fitting on the side of the engine block. If you notice the carpet wet under the dash behind the center console, you likely have a cracked heater core. If you see coolant or perhaps a white residue under your water pump, you likely have a bad water pump or bad o-ring. Temp sensors don't fail often, if they do it's usually due to air-lock causing the coolant to evaporate and blowing extremely hot air across the sensor which damages the sensing element. Or it may have a broken or damaged wire. So first thing, get your cooling system fixed. It's really important. I know, you can't fix the cooling system if the car doesn't run right. Right. So lets fix the electrical problem BEFORE YOU START DRIVING THE CAR with a bad cooling system. I mentioned earlier that your fan wiring might be the culprit. Return it back to stock. Did you say you got a new battery? If so, take your battery and alternator to your local auto parts store. Pep Boys, Advanced Auto, Oriley's, Auto Zone and Napa should have battery and alternator testing equipment. Most places will let you drop off your battery while they test it and charge it for free. If you want them to charge it, you have to ask them to, otherwise they'll just test it. They will also bench test your alternator right in front of you so you can see if it works or not. If it's bad, you can have your buddy rebuild it with new brushes, bearings and a voltage regulator. Or you can just buy a refurbished one. I get my alternators from this guy: http://stores.ebay.com/id=144108571 So lets say your alternator and battery are both good. Now you want to check the output. Start by cleaning off the battery terminals and cables with a wire brush. Buy, rent, borrow a digital multimeter. With the engine running and all electrical components turned off(headlights, AC, radio etc), check the voltage across the two battery terminals. You should see close to 14v, maybe a little over 13v. Now check the output at the back of the alternator. Place the red lead from the multimeter on the larger terminal on the back of the alternator. Place the black lead on either the smaller stud or it's easier to just touch it against a bare piece of metal in the engine compartment such as one of the strut tower nuts. Again, you should see about 14v. If you notice it rising and then dropping in voltage, you may have a bad engine ground. Turn the car off and check underneath the car on the passenger's side just inward of the front wheel well. There will be a large gauge wire connecting the passenger side motor mount to the cassis. Go ahead and remove this wire, clean the ends with a wire brush as well as the surface on the chassis and motor mount where it makes contact. Hook it back up and tighten the bolt nice and tight. Now go back and check if you have a steady 13-14v. If som you fixed your problem. If not, you have a parasitic drain somewhere. You can take your car to Sears or an independant mechanic to diagnose the problem. This will save you money vs. going to the dealer. Sears will usually test your charging system for free.