DIY for replacing expansion tank N62
 

Hi all,
I think I've identified the source of my coolant leak and have ordered a replacement expansion tank. I've used the search facility, but cannot locate a step by step procedure for this task. Any hints or suggestions would be appreciated. It's getting hot here now (40C+), so I want to ensure my cooling system is working well. TIA

I've never had to replace it...but just looking at it looks pretty simple. Looking up the diagram kinda verifies that it isn't that complicated.

It's secured to the bracket by two nuts (#5 in diagram)...3 cooling hoses...and the level sensor. Undo them and remove, then replicate what you did to replace.

The level sensor is in a dry well...so make sure you remove it from the old tank so that it doesn't get damaged.


Couldn't find a video for the e53...but there were 3 videos (click links below) for the e70, e65/e66 & the e60 (all n62 v8 engines)...you can see the similar BMW design architecture which you should be able to extrapolate to your e53 even though the location and shape may be slightly different...the hose clamps etc are very similar:

https://youtu.be/ktx5AkykObA
https://youtu.be/kCVyJPT9qXM
https://youtu.be/XxY9VL9e0d8

As you know, it is ideal to replace the orings in the hoses that are connected to the expansion tank. If they are the original hoses, they may be flattened or smoothed over from all of the pressure they have had to deal with. I am not sure of the oring sizes and if you can not find them and you get a leak, you will have to replace the hoses that connect to the tank.

Most people are fine not replacing the orings, but there are plenty that get leaks from the connection points and it is usually related to smoothed over orings.

Thanks both for the suggestions and tips. Didn't want to sound like a total moron, asking about what should be a relatively simple task, but wasn't sure if there were any hidden (read BMW) issues...
Will be replacing both HID bulbs while the expansion tank is out...wish me luck with the fiddly torxs screws at the bottom of the light covers...

Just be careful you don't break the nipple close to the expansion tank.....ask me how I know!:rofl:

Good luck. You should be okay though... it is a relatively simple task by BMW standards. I did a replacement 10 hours from home in a 7/11 parking lot just outside Las Cruces. Took less than 30 minutes (not including locating a tank). Ahhhh fun times.

Yup, pretty easy. Especially since the tank is situated well above the engine. Minimal coolant loss when playing with the hoses.

Cheers guys. I've noticed a small pool of coolant in the driveway, directly underneath where the expansion tank is located, so assume this is the problem item. On each occasion I've used the vehicle recently (about once every 2 weeks), I've had to top-up the expansion tank. First time it took only about 2 cups but most recently it took almost 2 litres of water.... I'm just praying it's not the dreaded transfer pipe job...
And as for your comment/suggestion Jopecasa - I'm pretty careful when it comes to playing with nipples - always treat them quite gently...