DIY: E46 Expansion Tank Removal Made Easy

[danewilson77]

It's a well known fact that the expansion tanks on E46's can be very stubborn to remove. I had read somewhere else, that pulling the "BMW expansion tank retainer", PC 10, below....then removing the expansion tank from PC 10, when it's out of the car...may facilitate easier removal. So That's what we did. I just took a bunch of pictures....which should describe what you need to do.

Added to DIY section as well....but most don't look there.

1. This is the Realoem drawing....showing the "Expansion tank retainer", PC 10.



2. This is the expansion tank and "Expansion tank retainer" as it will come out of the car.



3. So...what you will need to do...is remove two torx screws indicated on the below drawing, by the red dots.

Near the top of the "retainer"


Below drain plug


4. Once the assembly (Retainer and Expansion Tank) is out of the car, it can be separated rather easily.

These next pics show...that the expansion is simply "Hung" on piece 10, with bottom hose connections snapped into place.

The red dots below indicate the hanger on the back of the expansion tank, and the location it is hung.


Close up of hangar

***This is a pretty simple writeup...but sometimes a picture (or two or three) is worth 1000 words, so I hope this helps someone.***

5. An alternate method of removal is to skip all of the above, and place a hydraulic jack under the expansion tank (may have to raise up with blocks), and simply apply hydraulic jack pressure to the location, below, indicated by the red dot. This will separate both bottom hose connections and lift it off of the "hangar" point.



Enjoy a hassle free removal of your expansion tank today.

[renajb]

Thank you so much for posting this how-to since my expansion tank split down the side last week. I am getting ready to order replacement parts, but have a couple of questions.

1.) I was told I should always replace the cap when replacing the expansion tank, is that true?
2.) I read somewhere there is a expansion tank you should avoid, and one that is rated alot better. Have you heard about this, and if so have the part# for the higher rated tank?
3.) Should I replace the thermostat since I already have it apart even though I have a excellent heater?
4.) Are there any other parts you recommond replacing that are financial within reason (remember this is Christmas time)

Thanks in advance for all your help.

[danewilson77]

Understood about Christmas.

Honestly... If you can swing it.. Buy the ecs level I kit. It comes with a Meyle tank.

You really should try to replace upper and lower rad hoses, thermostat, water pump and expansion tank?

Yes... Get a new cap for you new tank.

How many miles on the car?

Sent from my Thunderbolt using BF.com

[PsychoCemia]

Speaking of ECS, their E46 cooler kits are on sale. I'm trying to decide between level 1 and level 2.

Any gurus wanna help me out here?

Link

Edit: Really, I'm looking at this kit Level 2 w/ aftermarket. However, the only kit I saw that specified the Meyle expansion tank was level 3 ($700 x.x).

[renajb]

I am right at 105,000 on the miles. I am replacing the tank/cap at the moment, but I plan to do the kit & radiator in Jan. Even though I havent had problems (until now) from what I am reading here, I will probably start to since the radiator will now become the weak link. Thanks so much for all your help!!

[renajb]

My son just replaced my expansion tank for me while I was at work. Only problem is that he found a "extra" part under the car when he was finished (not sure it even goes to my car) but he can't figure out if it actually does, and if so, where it goes. I have attached a pic. Does anyone recogonize this part?
Also he replaced the water lost out of the radiator when replacing the expansion tank. He just called and said now I have no heat!!?? Please help, I am at work and feel helpless trying to figure all this out!!!

[danewilson77]

Have him turn the car off. Make sure he plugged in the thermostat....and temp sensor.

Once everything checks out.....have him turn the key to position 2, without starting car.

Turn the fan on to low, and temp all the way up to 91*F.

Then.....tell him to add 50/50 coolant to distilled water, until it starts to come out of bleed hole in upper radiator hose.

This is called properly bleeding the system.

I would use the part above as a cool paper weight.

[bmwbob89]

That part is the thermostat for the auto transmission. It sits right below the tank.
Thermostat 117111437362

[Psyex]

Understood about Christmas.

Honestly... If you can swing it.. Buy the ecs level I kit. It comes with a Meyle tank.

You really should try to replace upper and lower rad hoses, thermostat, water pump and expansion tank?

Yes... Get a new cap for you new tank.

How many miles on the car?

Sent from my Thunderbolt using BF.com

I noticed you recommend getting a new cap for the expansion tank. What is the reasoning behind this? From what it looks like to me this is a cap that you can easily replace the O-rings and be good to go. It is not a pressure cap so you don't have to worry about having the 5lbs spring pressure like on North American cars. Is there an actual reason for replacing the cap or is this just because everyone else does it. Not trying to be disrespectful here either, Just wondering what I am missing. I have seen so many unnecessary parts changes for no logical reason then someone remembered that you used to have to do that during a tune up and these days there is no logical reason for the procedure.

[chefsboss]

O.K...So Holy Thread revival Batman!!..
I know this is an old one... But it is absolutley amazing how much easier it is to R & R an exp tank like this.
But For discussion sake, I wonder if the only reason it is such a pain in the apple the other way is only because of this little bracket clip?
And so removing the bracket allows a little play in the parts to do it without getting both mounting holes and the bracket perfectly aligned for that success "snap"

In other words... It undisputabley is.... but WHY is this so much easier??? it's got the engineer in me curious. thoughts???

[325Max]

#5 from the original post works for me! Thanks Dane.

[Kashmod11]

Does the expansion tank keep the fluid from power steering seperate from ATF? I just put a new motor in my 03 325xi and my reservoir going to rack and pinion, pump, was empty. I put Pentosin hydraulic system fluid in it, then realized the cap says ATF fluid only.... How bad did I just mess up or is it a power steering res? How do I check level of AT? It's my first bimmer and in the three years I've owned it have now completely went threw suspension and a motor swap. I'm kinda ignorant to a lot about these cars and need you all every time I turn around. So thanks to all the men and women on here who share the love I do for the BMW and the German engineers who built them.

[jmo69]

Does the expansion tank keep the fluid from power steering seperate from ATF? I just put a new motor in my 03 325xi and my reservoir going to rack and pinion, pump, was empty. I put Pentosin hydraulic system fluid in it, then realized the cap says ATF fluid only.... How bad did I just mess up or is it a power steering res? How do I check level of AT? It's my first bimmer and in the three years I've owned it have now completely went threw suspension and a motor swap. I'm kinda ignorant to a lot about these cars and need you all every time I turn around. So thanks to all the men and women on here who share the love I do for the BMW and the German engineers who built them.

Change out the hydraulic fluid from the power steering and the transmission has to be checked withe the car level, warm and the engine running by removing the fill plug and the fluid should just seep out.

[z168]

Thread revived!

Thanks for the info - wish I looked this up sooner. Seemed like a straight forward process. Given I still had the original expansion tank (MY99) it was practically glued together. Easier way was DaneWilson's method.

[BMWAccelerator]

Great, I will use this DIY next week when I get the parts.

[jczr2]

I noticed this morning that my tank cracked. I ran to the dealer to buy a new tank and lower thermostat. I took off that lower heater hose not realizing that i didnt have to. I cant seem to get it to seal. it says a 1.25" o ring goes in there but it just seems way too big. in my part of Maryland we are in the middle of a major snow storm. i got most of it done before it hit, but cant figure out what is missing to get that hose to seal. Does anyone here have any info on that? Thanks in advance.

[323i jlviii]

Doing the same job. That tank was beyond difficult to remove - I thought it was glued. Looked thru every post, you tube, I could find. Still nothing that tells
you that the thermostat in the bottom is for the automatic transmission cooler? And that it will probably break in the removal process. I believe it's brittle and
it's better to replace it anyway with where it's located.

Watching videos of numerous guys trying to remove that tank is scary! Next camera shot is the tank out or they removed the whole assembly with the plastic part. And continue as if that's good?

I thought this is unbelievable, why, how is this thing (tank) still in here? Pull, Pull and wiggle, pull some more! Man. How to pry it off from the lower connection? Nothing fits to do that, Pry bar from the frame to the bottom of the tank almost works. Remember the slow and easy pulling, you will break the thermostat in the bottom if you man-handle it. I think it's like an egg shell, touch it and it will break.

So here's what I tried and it seemed to work better than everything else I saw. Remember this is a slow, very slow and easy process; there is only a 1/2" or less before you hit the radiator connection. Once the tank begins to move stop using the pry bar and now go back to grabbing it with your hands and pull and lift slightly back away from the radiator connection. I put a shop rag down first so I'd protect the paint. Fingers inside the top opening to steady the pry bar. Slowly push the bar down while steadying your fingers on the inside to slowly pry it up.

See picture, Prying Expanison Tank.jpg wow, it actually showed up. cheers!

[BMWAccelerator]

When I did this I had the shop do my radiator and expansion tank. They had a difficult time. Glad I didn't have to do it. Money well spent.

[Danegerous]

When I did this I had the shop do my radiator and expansion tank. They had a difficult time. Glad I didn't have to do it. Money well spent.

Hey how much did they charge you to do it? And was a BMW shop, or just a shop that you trusted?

[BrittB]

I'm doing my system as well and replacing everything. My expansion tank looks like new and popped out very easy but the parts I had trouble with were the thermostat for the transmission and the heater hose that connects to it. The P/S reservoir has been leaking on it and swelled the o-ring inside the hose so I'm replacing the water connection pipe as well. Also had to buy a expansion tank mount because I chipped an edge trying to unsuccessfully remove that stupid trans thermostat! Since I'm still waiting on parts now would be a great time to tackle that oil filter housing leak, just having trouble getting that damned alternator off! I tried the tapping on the bolt trick...., nope!!!

[BrittB]

Got everything back together only to have it leak the coolant right back out. I destroyed an O ring on the trans cooler putting it back in but I had new ones in stock so it was a quick fix. Those were the only two o rings that looked good enough to use, I was wrong! Oh well, nice to have it back on the road again.

[Hawaiian11]

dxzcdtfas6wt

[vardolov]

Hi guys ,
Can you tell me , the number of part wich is the number 10 /ten/ from drawing,
becouse my was broken.
I'll be very thankful.
Best regards.

[Moylo]

I don't know if it's too late for you vardolov but 10 appears to be the expansion tank base. The part number for the automatic/steptronic base is V20-1381. Not sure what the manual one is, sorry.

This thread was very helpful, thanks. I'd definitely recommend method number 1 and removing the entire tank base along with the tank. I successfully removed the tank using the hydraulic jack method, however I had massive trouble trying to get the new tank to seat without leaking on the flanges. I ended up removing the entire base in the end and bench fitting the tank to ensure that there were no leaks. Worked a treat!

[MIKYZZ4]

Replace the cooling parts as a cooling system, not part by part.
Because the cooling system is made up of basically all plastic parts,
a cooling system overhaul is the recommended fix, as they all become brittle over time.
If one part becomes brittle and cracks, the rest are soon to follow.