If you own a pre-OBD 2 BMW, especially an E30, there are three indispensable tools: a smoke machine for finding vacuum leaks, a radiator pressure tester for coolant leaks, and the focus of this post, a torque screwdriver for worm gear hose clamps.

Older BMWs are from a generation that predates the use of constant tension hose clamps, where worm gears are common.

Under-tightening might seem okay initially until the hose settles and begins leaking. Over-tightening, however, can significantly reduce the hose’s lifespan.

Often, hoses are initially under-tightened and then over-tightened once a leak is discovered.

Regardless of how well-calibrated you think your hand is, achieving the correct tension is surprisingly challenging.

You should aim for 2.5nm for almost all clamps on an E30.

The good news is that since you set it and forget it at 2.5nm, tightening worm hoses and checking tightness periodically becomes super fast.

I personally use a ‘CDI Torque Products TorqControl TLA28NM’ with a 1/4 bit to socket adapter. However, any reputable torque screwdriver with a minimum range of 2nm should be perfectly adequate.

This entry was posted on January 7, 2024 at 10:26 pm and is filed under Interesting Stuff. You can follow any responses to this entry through the RSS 2.0 feed.