Original BMW Thermostat Housing O-Ring 45x3.5 mm for BMW M240i, 340i, 440i, 540i, and 740i (2016–2021)

Sized at 45 x 3.5 mm, Original BMW gasket ring 11-53-8-658-572 is the O-ring that seals the thermostat to the water pump on the B58 six-cylinder in the BMW M240i, 340i, 440i, 540i, and 740i. O-rings like this sit in a groove and compress between two parts, holding coolant in under pressure and heat. BMW requires this O-ring to be replaced whenever the thermostat or the water pump is replaced, because it is a one-time-use seal. A failed ring here is a common point for coolant leaks. It weighs 2 g, is made in Italy, and is sold individually.

The 24-month Original BMW Parts warranty covers this O-ring.

BMW calls this part a gasket ring and has produced it since July 2015, which places it with the B58 engine generation. BMW's parts data shows the same ring on the F22 M240i, the F30 340i and F34 340i Gran Turismo, the F32 and F36 440i, the G30 540i, and the G11 and G12 740i, so a single part number covers every B58 car in the store fitment.

Technical Details

• Manufacturer: BMW, genuine part
• Part number: 11-53-8-658-572
• BMW part name: Gasket ring
• Size: 45 x 3.5 mm
• Weight: 2 g (0.07 oz)
• Position: thermostat to water pump
• In BMW production since July 2015
• Made in Italy, sold each
• Warranty: 24 months

Common Questions

Can I reuse the old O-ring?
No. BMW specifies a new ring each time the thermostat or water pump is replaced.

What size is it?
The ring measures 45 x 3.5 mm.

Order the seal with your B58 cooling parts from PMB.

Fitment & Compatibility

Use the fitment table below to confirm year, model, submodel, and application notes before ordering. With over 20 years of parts and fitment experience, PMB Performance can match this to your VIN.