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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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Old 06-22-2013, 10:33 PM
ztom's Avatar
ztom ztom is offline
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Location: Thousand Oaks CA
Join Date: Sep 2007
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Mein Auto: 1997 528i
Radiator expansion tank swap and drain plug installation

Just replaced the expansion tank on my 2003 325xi. This is the second car of this type I've done this because it had a very small crack along the side (that you can't see unless you take it out.) I read this is a common problem with the e46.

The bottom has a large hose that is a simple slide lever to disengage (see the replacement tank). It also has sensor that takes a 90 degree turn to remove (turn it CCW while looking down). I could have left the sensor intact, then do the turn once the tank is lifted up a couple inches.

The tankremoval is smooth except for pulling it up. TIP - I put vise grips onto lip of the old tanks with a cotton glove as a cushion. Then on the back of the vise grips I put channel lock pliers, then hit the channel lock upward with a hammer, tap, tap. Need the impact to kick the tank upwards to disengage.

I ran into problems putting the radiator drain plug back in. I screwed it in but it snapped, was not much torque. Then I bought a new plug, comes as an assembly with the black hex outer housing. In doing a 90 deg CCW turn (looking up) the black hex housing cracked off. Then when I tried to screw into what was left to pull it out, it got pushed in. TIP - I used a coat hanger wire and fashioned a very short "L" hook on the end so I could pull the center part with the 0-rings out. Study the replacement part.

Then getting the new hex housing in was easy BUT the hex has locking tabs and it is NOT 180 identical ie there's only one way to line up the tabs. Study the hex. It has a small black tab to stop the rotation and you can see what it will hit during rotation. With the right 180 orientation, just line up the tab to the slot and push, it goes in easily including the wing tabs. Before insertion I used a gloved finger to wipe the cylinder inside to be free of grit, then put a fine film of grease to help the push in. If you broke the old tabs, check that pieces are still not stuck in there.

After fill, drive a little then cool, then open the cap and fill again til the stick pops up. I didn't find it necessary to use the bleed screw.

Last edited by ztom; 06-22-2013 at 10:37 PM.
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Old 06-24-2013, 06:52 AM
Augster Augster is offline
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Location: Sandy Eggo
Join Date: May 2013
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Mein Auto: M1A1 Abrams
For me, I was completely surprised just how easy my ET came out as all it took was following the BMW service guidelines of pulling up slightly, then tilting slightly to the rear of the car and pulling up. Not much strength nor force was required to take mine out. But getting the new one seated was more eventful and I had to support the radiator with a block of wood on a hydraulic jack, lubricate the ET lower openings with mild soap, then applied the force of my entire body weight a couple times to seat it completely. No leaks.

I'm not sure its prudent to feel you don't find it necessary to bleed the system as all you've done is to ensure the coolant level is consistent but that in and of itself will not ensure you've rid yourself of all air pockets trapped in the system. I believe it was trapped air pockets which caused my coolant level sensor to trip on now and then, but hitting a bump or taking a sharp turn or shutting down the car for awhile would always turn off the level warning light.
2008 335i Sport Sedan AT
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