Coolant Expansion Tank Replacement

Alright, so it's been a long long time since I did any real car maintenance or mods. The good thing is that the M3 has been pretty much running the last 6 months without a hitch. A few things need addressing and I am stock piling a lot of parts so I'm going to start things back up with a few easy things. Also blogger has a sweet new format, shit just got real!

Earlier this week I noticed I was losing coolant too quickly to not address it. I was getting the, "Low coolant level," warning on the OBC every other day after adding 4-6 oz here and there. I figured it was from the t-stat housing or water pump having noticed a little drip from there awhile ago and assumed the issue was just getting worse.

When I went to take a closer look I noticed spots of coolant all over the shock tower, radiator hoses, valve cover and fan shroud. Uh-oh, did a little more sleuthing and found a small crack fizzing on the expansion tank. Having just replaced that tank last year I was a little pissed. I called RMeuropean to see if there was a warranty and there was! I had 10 days left. They sent me a new one and told me to ship back the defective unit.

So here you can see where the coolant was spraying out everywhere.

Level is a little low

Removing this thing pretty much sucks. I ASSUME it's easier if you remove the fan shroud and everything else, but the way it is hooked up, I can't imagine so. The hoses are all hidden and fit in only one direction. It's a pain in the ass. You have to be pretty patient. Other than patience, removing it is rather simple.

There is a level sensor on the bottom as well as the main hose. There is a overflow smaller hose connected at the top. Once you remove the vent screw, which is brittle and plastic, you can pull that clip out and it should free the tank up. Then you can pull it around to give you room to access the hose clamps. Like I said, accessing the hose clamps require midget hands and luck that they are pointing the right direction to get a socket or screwdriver to turn them.

Here's the old tank after getting it out. You can see the little crack there that has nothing to do with the molding flash. I suppose it was just a bad part. It was enough to fizz out coolant everywhere at high pressure.

Here's the new one. Same thing, hopefully no crack. The BEHR unit doesn't fit exactly perfect and it's off white. The BMW brand tank is $78 vs $41 for the BEHR. It may or may not be worth the extra $40 to get the BMW one. Either way this one is warrantied for 1 year. Yippie.

So I managed to over torque the plastic vent screw upon reinstallation. There is a little o-ring that I was missing so when I saw coolant leaking around the screw I tightened it some more, good idea right? Well that ripped the little plastic head off with the screw embedded in it's home. Luckily it was Friday and the New Century BMW dealer is right down the street. I always reserve the opportunity to pay 250% mark-up for emergencies or urgent matters. I felt like I could afford a screw.

This image shows a $1.50 screw for $3.59 as well as the only time known to man that an easy-out has ever worked. There it is, documented, the first ever successful attempt with an easy out. RMeuropean sells a brass version of this screw that I may have to pick up.

Alright, so that's it. Here it is installed all nice and clean without leaks. Woo!