Bomunik Aluminum Expansion Tank with Cap — G30/G32/G11 B46/B58
by Bomunik
Key Features
- Cast aluminum construction resists heat-cycle cracking that plagues OEM plastic reservoirs
- Direct-fit replacement for BMW G30/G32/G11 chassis with B46 and B58 engines
- Includes matching pressure cap — complete kit, no separate purchases needed
- Covers 525i, 530i, 540i, 630i, 640i, 730Li, 740Li, and 840i (2016–2024)
- Cross-references 30+ OEM and aftermarket part numbers including 17138610656 and 17139846642
- DIY-friendly drop-in fitment requires no modifications or professional installation
Product Details
- Brand
- Bomunik
- Part #
- 17139846642 17138610656 17138742975
- Category
- Expansion Tanks
- ASIN
- B0FB36B6QY
Check if it fits your BMW
Bomunik Aluminum Expansion Tank with Cap — G30/G32/G11 B46/B58 — Overview
The factory plastic coolant expansion tank on BMW's G30, G32, and G11 platforms has a well-documented weakness: years of heat cycling cause the reservoir to become brittle, crack, and leak — often with little warning. Bomunik's aluminum expansion tank eliminates that failure point entirely, replacing the vulnerable OEM plastic with a cast aluminum unit engineered to handle the thermal demands of both the turbocharged B46 and the high-output B58 engine families without degrading over time.
Fitment spans the full range of affected models, including the 525i, 530i, 540i, 630i, 640i, 730Li, 740Li, and 840i from the 2016–2024 production years. The tank is a true drop-in replacement — same mounting points, same hose connections, same footprint as the OEM unit — so there are no modifications, adapters, or fabrication work involved. Every kit ships with a matching pressure cap, meaning you have everything required to button up the job in a single order.
Confirming fitment is easy: this tank cross-references over 30 OEM and aftermarket part numbers, including 17138610656, 17138742975, 17139846642, and 17139884859, among others. If your existing reservoir carries any of those numbers, this is your direct replacement. The broad cross-reference list also makes it simple to match against dealer part numbers or whatever is currently on the car.
Bomunik stands behind this part with warranty coverage — if the tank fails in use, contact them directly and they will make it right. For any G30, G32, or G11 owner chasing a coolant leak or getting ahead of a known failure, this aluminum reservoir is a smart, lasting fix at a fraction of the cost of repeated OEM replacements.
Other Expansion Tanks
Recommended for Your BMW
Mishimoto 16-Row Thermostatic Oil Cooler Kit — Universal
Mishimoto
Mishimoto 25-Row Thermostatic Universal Oil Cooler Kit
Mishimoto
Mishimoto 25-Row Universal Oil Cooler Kit
Mishimoto
MITZONE Coolant Thermostat Housing Assembly — B46/B48 2.0L
MITZONE