I bought a 2001 325iT earlier this week, it is a 5 speed with 116,000 miles on the clock. The car came from a dealer and I got it for an "as is" steal of a price (or it was a steal IMO). Today I drove about an hour on the interstate and when I parked at home there was some steam coming from the grill (not a ton, just a little). I popped the hood and couldn't locate the exact point of origin but it was definitely around the radiator. I had to drop off a rent check so I drove a few blocks and the coolant light came on, the temperature is still dead center. After driving a few blocks further the coolant light switched off. I went into a store and when I restarted the car the coolant light came back on after a few blocks and then switched off as I neared my house. When I parked at the store and at home there was no steam. Any idea why this would be? I'm thinking I may need a new radiator and the coolant doesn't get hot enough on short trips to cause any steam?
Any help would be appreciated, I'm not super familiar with cooling systems.
Thanks,
Joshua
It's probably telling you that it's time for the regular BMW cooling system overhaul.
In reply to BoxheadTim:
Yup, time for a radiator, water pump, hoses, and anything plastic in the cooling system.
Bingo. You might have a cracked expansion tank, or maybe one of the plastic radiator end caps is leaking. At 116k, chances are the 100k cooling system overhaul was not done and now the components are starting to fail. ECSTuning.com sells various packages to get the job done; I recommend the EMP Stewart water pump if you're planning to keep the thing indefinitely, as it will never need to be replaced again and is a sizeable flow upgrade.
If you value your engine, STOP DRIVING THE CAR. The all-aluminum M54 does not tolerate overheating of any sort, no matter how short the duration, without a very significant chance of warping the head and ripping head bolt threads out of the block.
When you replace the system, do it all and don't cheap out on the parts; all OEM Behr should still be under $600, including all the major bits plus the fan clutch. Personally, I like to replace the plastic bleed screws with brass (aftermarket). Don't forget to drain the block as well. When you refill, raise the nose of the car about a foot off the ground, turn the key to ON, and set the heat to the highest temp - this will get the aux. pump going and help to ensure you don't get air in the system (which is notoriously difficult to bleed).
Kenny_McCormic wrote:
In reply to BoxheadTim:
Yup, time for a radiator, water pump, hoses, and anything plastic in the cooling system.
This is the gospel according to BMW: thine coolant system shall ascend unto heaven at 100,000 miles and you shall descend unto hell if you don't replace it.
In reply to Timeormoney:
German engineering can do that, look at MINI, they made a German car act like its British!
the good news is.. replacing the cooling system is not a hard job.
cwaters
New Reader
1/3/14 7:25 a.m.
Joshua wrote:
Any help would be appreciated, I'm not super familiar with cooling systems.
You're about to be. 
As has been said already, order the whole kit and swap it out. Today.
Top tip: Under no circumstances leave the fan lying on the driveway where you can step on it and break off a couple blades. This can seriously delay your project completion.
I uh... heard of somebody who did that once.
+1 on the advice to fix it immediately. Go on the GP/Vendors forum on Bimmerforums (http://forums.bimmerforums.com/forum/forumdisplay.php?125-Group-Purchases-amp-Supporting-Vendor-Specials-presented-by-eBay), give them the part numbers from RealOEM (http://realoem.com/bmw/), and it should take an afternoon. For my E36, the tools that I needed were a 32/36mm open wrench, a 19mm open end wrench (coolant block plug), and one of the tools to keep the fan clutch from spinning. Here are my notes on my E36: http://grassrootsmotorsports.com/forum/grm/e36-cooling-system-overhaul-notes/13016/page1/
Make sure you change the radiator cap when you do the cooling system. People often overlook those things.
As for the gauge needle staying in the center, these BMW coolant temp gauges are a bit funny. I don't know why, but they are a bit like idiot lights. They move to center at the first sign of engine heat, and don't move off center unless they are really hot.
Don't chance it, just fix it. Welcome to BMW ownership, they aren't that hard to maintain, but there is a lot that needs maintaining.
