B46 / B48 Turbo Coolant and Oil Lines

IA EURO illustration of the BMW B46 / B48 turbocharger with the exhaust manifold cast in, the coolant and oil line ports on the center housing circled in red marker: all lines 8 Nm, the turbo stays on the car

B46 or B48? Same engine family. In the US, BMW badges the 2.0 turbo in the 330i, 430i, 530i, 230i, X3 30i, X4 30i, Z4 30i and X1/X2 28i as a B46. B48 is the hotter version: X2 M35i, M235i, MINI JCW. BMW's own repair book files them all under B48, and the turbo lines come off the same way. Coolant or oil, none of them need the turbo off.

Which line is wet?

Two coolant lines and two oil lines bolt to the middle of the turbo. Green or pink crust is coolant. Black and wet is oil.

Feed lineComes up from the engine block to the bottom of the turbo. The cat comes out to reach it, from underneath.

Return lineLeaves the top of the turbo for the little electric coolant pump. Done from the top, no exhaust work.

8 NmEvery line bolt on both ends is a small M6. BMW says 8 Nm. Torque it like a wheel bolt and you are chasing stripped threads in a turbo.

The turbo stays on the car. BMW's book pulls the turbo to change the oil feed line. We don't. With the cat out and the coolant lines out of the way, the feed line comes out with the turbo still bolted to the head. The coolant lines and the oil return line come out with the turbo on in BMW's book too.

Find your lines

BMW changed the lines in 2019. Go by the build date on your door sticker. Both lines use the same O-ring, BMW 11 53 7 610 049 (9.7 x 1.5 mm), and you want a new one on every end you open.

F30, F32, F22: 330i, 430i, 230i, all years · 530i and X3/X4 30i built to mid 2019Feed 11 53 7 643 094
Return 11 53 7 643 226

G20 330i and Z4 30i from 11/2018; 530i, X3 and X4 30i from 07/2019Feed 11 53 8 629 971
Return 11 53 8 651 261

X1, X2, M235i, MINIDifferent lines by year. Send us your VIN.

Torque

Feed line to engine block8 Nm

Feed and return line to turbo8 Nm

Return line holder to turbo8 Nm

Cat to turbo clamp, G-series (new clamp)13 Nm

Cat to turbo clamp, F30 (new clamp)32 Nm

Cat to holder (new nut or screw)19 Nm

Stiffening plate under the engine, G2056 Nm

IA EURO illustration of the BMW B46 / B48 turbo coolant return line in blue: bolt-on turbo end with a new O-ring at 8 Nm, quick-connect pump end that clicks in — The coolant return line. The turbo end bolts on with an O-ring. The other end is a quick connector on the little electric coolant pump: push it on until it clicks.

Feed line

Engine covers, intake pipe and the front O2 sensor come off up top.
Underneath: splash shields and the stiffening plate. Don't drive without that plate.
Drain the coolant. BMW calls it lifetime fill, but it doesn't go back in.
Exhaust down, cat out. On a G20 the whole exhaust comes off first. Mind the rear O2 sensor on the cat.
Two bolts: one at the block, one at the turbo. Line out.
New O-rings on both ends, bolts to 8 Nm.
Cat back in with a new clamp, seal, nuts and the little pressure hose. BMW lists all of them as one-time.

Return line

Engine covers and intake pipe off. Splash shields and the stiffening plate underneath.
Drain the coolant.
Unbolt the feed line at the turbo and move it aside. It's in the way. That end gets a new O-ring too.
Unbolt the return line and its holder, then unclip it at the electric pump and feed it out the top.
New O-rings, everything to 8 Nm, clip it until it clicks.

Oil lines

The oil feed line takes the same O-ring as the coolant lines, 11 53 7 610 049. The oil return line takes its own sealing ring, 11 42 8 604 872 (16 x 2 mm). New ones at both ends of both lines.

G20 330i from 11/2018; 530i, X3/X4 30i, X1 28i from 07/2019Feed 11 42 8 629 969
Return 11 42 8 629 970

Older F30, F32, F22, G30, G01BMW made several feed lines. Send us your VIN.

Oil feed line to turbo and to block (M6 x 12)8 Nm

Oil return line to turbo and to block (M6 x 14)8 Nm

IA EURO illustration of the BMW B46 / B48 turbo oil return line with heat wrap: a new sealing ring at both ends, 8 Nm — The oil return line. BMW used a heat-wrapped one and a corrugated steel one. Same job, same seals.

Oil feed line

Same teardown as the coolant feed line: covers, intake pipe, front O2 sensor, splash shields, stiffening plate, cat out, coolant drained.
Move both coolant lines off the turbo. They're in the way.
Pull the oil return line first. Have a rag ready, some oil comes out.
One bolt at the turbo, one at the block. Feed line out. The turbo stays put.
New O-rings, 8 Nm both ends. Keep it clean: dirt in this line goes straight into the turbo bearings.

Oil return line

No coolant drain, no exhaust work. Engine cover, intake pipe, splash shields, stiffening plate and the cover under the steering rack.
Two bolts, one at the turbo, one at the block. Rag ready.
New sealing rings at both ends, back in, 8 Nm.
Check the oil level when you're done.

Coolant: do it BMW's way

Vacuum fill it. BMW says pouring it in from a jug isn't allowed on this engine. You'll trap air and cook something.
Then run the bleed. Wheels on the ground, hood shut, parking brake on, P. Low beams and hazards on. Press start 3 times without the brake. Heat on max, fan on low, not in ECO PRO. Hold the gas to the floor for 10 seconds, then start it.
Let it run 11 minutes. It revs itself up to 3,500 rpm and cycles the pumps. If it stops early, do it again.
Top it off once it's under 50°C: 200 ml over the MAX mark. It settles while you drive.

Don't run the bleed with a circuit empty. The electric coolant pump runs dry and dies. Fill first, then bleed.

Where people mess it up

Reusing O-rings. They're cheap, and you'll be doing this twice.
Torquing like a wheel. 8 Nm is barely past snug.
Skipping the bleed. The level looks fine, then the car overheats in traffic.
Old cat clamp back on. Now you've got an exhaust leak too.
Pulling the turbo because the book says so. You don't need to for any of these four lines.

Steps and torque values come from BMW's repair instructions for the turbo coolant lines (11 53 082, 11 53 086) and oil lines (11 42 200, 11 42 210) on the B48 family. Doing the oil feed line with the turbo on is our shop's way, not BMW's. Part numbers come from BMW's parts catalog for cars built up to 12/2019. Check yours by VIN.