BMW B58 Turbo Install Kit, Gen 2 B58 (B58D),for G20 M340i, Z4 M40i, X3 X4 M40i 2019-2020: Manifold Gasket, 7 Nuts, 7 Bolts, Line O-Rings, Downpipe Gasket

This guide follows BMW's own repair instructions for the 2019 and newer G20 M340i xDrive (B58, second generation). The same turbo comes out the same way on most B58 cars. We list where the F-series cars (340i, 440i, M240i) differ. Upgrading? The swap is the same job as a stock replacement. The tune, the fuel and the parts around it are what change.

Read this before you start

• Order the right manifold gasket. The G20 M340i uses 11658669733. Earlier F-series B58 cars use a different gasket (11657643149). Check your car before you order.
• Bigger turbo means a tune first. A bigger turbo on the stock software gains nothing. Have your tune (MHD or similar) ready before the car leaves the stands. Newer G-series DMEs can be locked and may need a bench unlock before any flash tool can write to them, so check yours before you buy the turbo.
• Catted downpipes only. Remove the catalytic converter and you have an illegal car and a failed inspection.
• Plan for coolant and oil. The turbo's coolant lines drain a lot. You will drain the high-temperature cooling circuit and refill and bleed it after. Do an oil change with the job. A fresh turbo should never see old oil.

Tools and parts

• Jack stands or a lift. This is an underbody job on the G20.
• 22 mm oxygen sensor socket, torque wrench that reads down to 5 Nm, plastic trim tools.
• Coolant drain pan, fresh BMW coolant, a vacuum coolant filler if you have one.
• BMW turbo additive, 17 ml (BMW 83195B305D6), and fresh engine oil to prime the turbo.
• All the one-time seals, nuts and bolts below. Never reuse them.

Gen 2 kit (G20 M340i, Z4, 2020 X3/X4 M40i) Gen 1 kit (340i, 440i, M240i, 540i, 740i)

The passenger engine mount

BMW's own turbo procedure for the G20 leaves the engine mounts alone. On the shop floor, the passenger (right) engine mount usually has to come off so the engine can be raised a little and the turbo has room to come out. If you do it:

• Support the engine from above with an engine support bar before you touch the mount. BMW raises the engine only 10 mm for its mount job.
• Lower the engine fully onto the mounts before you tighten anything, so nothing is preloaded.
• Engine mount to front axle support: M8, 19 Nm. Mount bracket to engine: M10, 38 Nm. Mount to bracket: new M12 bolt, 110 Nm.
• Replacing the mount while you're there? The passenger side is BMW 22116860472 on the G20 M340i.

Removing the turbo: the short version

1. Engine cold. Hood to the service position. Remove the engine covers, the front-end struts and the top cross braces.
2. Remove the fan cowl, the intake silencer housing, the engine ventilation line and the clean air pipe.