Coolant leak? E46

[Bimmer606]

It seems I have a coolant leak. Friday as I was walking to my car after work i noticed some coolant had leaked. I turned on my car and the coolant light turned on but as soon as i hit reverse it turned off. I drove home monitoring my temp gauge and all seemed normal. The light did not come on again the whole way home which is a 20 mile drive. On Saturday we jacked the car up took a look under to see if we can tell where the leak was coming from. We didn't really see much but the only place it seemed to be wet was close to the blue drain plug. We went to the stealership and picked up a new drain plug which included the adjuster, removed the old one and put the new one except we had to use the old blue plug because the new one was cracked nice huh?

Tonight we drove the car 10 miles and temp is normal but as we were driving the coolant light turned on again. When i came to a stop light the light turned off and came on again shortly after i took off. Another stop light and it turned off and then back on once i started to drive.

One thing to note is i had my thermostat changed in January. Didn't check the coolant again until Friday. I assume that it had been leaking out for a while now. My car has never overheated and temp is always normal. WTF?

Not sure what's leaking, can anyone give me a suggestion or two where to look or what it could be?

Any help would be appreciated

[danewilson77]

How much coolant do you have to add each time? Couple of cups? what prompted you to replace the coolant drain plug?

Try piece 5 where it connects to the radiator. Those water pipes become hard and brittle, and with vibration and heat....they develope leaks...

[Bimmer606]

The thing is yesterday was the first time we added a quart from a premixed bottle of bmw coolant we had from when we changed the thermostat. We just jacked up the car now to see if we can locate the leak yet again. Its coming from the side where the expansion tank it at and that pipe you pointed out. However it doesn't seem to be the pipe. Its looking like the expansion tank might be the culprit but we are still examining it lol. Before we left to test drive the car had coolant. once we came back and jacked the car up no coolant in the expansion tank.....

Yep,the expansion tank is the little bastard leaking....

[2000e46ci]

Its the cheap plastic expansion tank. The stealership asked if I want a new rad as well that they go at about the same time. I declined and just installed the new expansion tank and upper hose. All fine now. Its been almost 2 years.. no probs.

[Reichling]

+1 on piece #5 as well, these always seem to leak as they get older. hope all goes well

[telijah]

Remember, these tanks are notorious for failing, so depending on mileage, it may be a good idea to go ahead and replace the expansion tank. If you didn't change your upper and lower hoses when you did the t-stat, you should go ahead and do that too.

[nathancarter]

A cracked plastic expansion tank is very common.

Don't procrastinate or screw around on this; if you overheat, you'll destroy the engine. These aluminum engines can't withstand overheating like the old cast iron blocks.

[Bimmer606]

Hello everyone. Thanks for all the suggestions. I've gone ahead and order a cooling repair kit from tischer which includes pretty much everything except the radiator. I figure might as well get it over with. My car has 70,500 miles. I hope to receive the kit by this weekend along with the fan clutch tools. I'm checking the coolant every morning and before i leave work so if i feel it is low i just add more. Luckily i work only 8 miles away.

[telijah]

That is probably the best. At 70k, you probably don't need all that, but then again, if you do the whole kit, you won't have to worry about it again for quite some time, making it well worth it.

[crazyassailant]

We didn't really see much but the only place it seemed to be wet was close to the blue drain plug. We went to the stealership and picked up a new drain plug which included the adjuster, removed the old one and put the new one except we had to use the old blue plug because the new one was cracked nice huh?

Found this old post while researching my own little coolant mishap, hopefully op is still active...
Bimmer, was there anything complicated in removing the adjuster or installing the new one? How did you go about it? I saw coolant pouring out of the blue screw today after my car warmed up in my driveway and want to replace it asap. Thanks!

[MillerTime1nine]

To replace the expansion tank you just need to remove a few clamps and yank it out for the most part. And it WILL be a bitch to get out once the clamps are removed.

there a plenty of DIYs like this one around if you need help:
http://www.bimmerfest.com/forums/sho...d.php?t=415259

[danewilson77]

Found this old post while researching my own little coolant mishap, hopefully op is still active...
Bimmer, was there anything complicated in removing the adjuster or installing the new one? How did you go about it? I saw coolant pouring out of the blue screw today after my car warmed up in my driveway and want to replace it asap. Thanks!

Not positive what adjuster he/you... is/are referring to....

[crazyassailant]

Not positive what adjuster he/you... is/are referring to....

No. 3 on this diagram... part number 17111437360. The blue radiator drain plug sits inside of it.

[Beachumz]

Yep, thats the same problem my car had awhile ago. Coolant light came on when car started then shut off after putting it into gear. I drove right to auto zone since no dealership anywhere near by, and checked the level...it was almost bone dry! but it was still normal temp and everything! maybe the sensor is going bad as well?

[MillerTime1nine]

Yep, thats the same problem my car had awhile ago. Coolant light came on when car started then shut off after putting it into gear. I drove right to auto zone since no dealership anywhere near by, and checked the level...it was almost bone dry! but it was still normal temp and everything! maybe the sensor is going bad as well?

Thats not good at all. It was almost completely empty? how far away was the autozone? If you drove any distance with no coolant it defiantly would have overheated, you didn't smell anything or notice any fluid leaking on the way over there?

anyways, I would check the sensor asap.

[rowdy lee]

I liked the part about the SIX MONTH INSPECTION CYCLE...

and, if there hadn't been an obvious problem, the coolant never would have been checked!

must be that lifetime coolant/sealed system... duh, thanks BMW!

Wait... what?

[psychocandy]

Had this same issue a few mos ago....changed the thermostat, water pump and belts as preventative maintenance and about 2 mos after that began experiencing the symptoms you described. Changed the expansion tank and problem solved. Although, upon removal I didn't see any visible cracking that some show in DIYs, I am thinking perhaps the rubber seals just hardened over time and began to slowly leak...

[eoinfarrell]

So happy to have found this, bought expansion tank along with upper and lower hoses. Put in tank and upper hose, no joy.
Decided to jack up car and fill coolant, revved at 2000rpm for a while and spotted coolant squirting from the lower radiator hose on the radiator side. Getting the part on Monday.

[tonythetiger]

For that was the hoses & expansion tank? I just had the expansion tank replaced a year ago