The M20 engine platform found in E30's is prone to substantial vacuum leaks, nowhere greater than at the elbows found on the TB. The original elbows are press-fit from the factory and come loose over time. Not only are these parts NLA (No Longer Available), but it wouldn't matter because an OEM part would still be loose.

What many people do is try to glob silicone or JB Weld; almost always with failure, once again not long after.

These are reengineered elbows that utilize two Viton O-rings to seal the connection. This is a permanent, serviceable solution that will last your E30 a lifetime and finally rid you of vacuum leaks.

The parts are CNC machined from 6061 aluminum on a 5-axis machine. Grab one while you can; I've done an initial run and may never do one again.

More details:

https://www.rtsauto.com/cnc-throttle-body-booster-side-elbows-fix-for-vacuum-leak-e30-m20-engines/

https://www.rtsauto.com/vacuum-leak-location-on-e30-throttle-body-m20/

We also offer an ICV CNC elbow:

https://www.rtsauto.com/cnc-icv-elbow-fix-for-icv-elbow-vacuum-leak-e30-m20-engines/