LOUD HUMMING NOISE.

BMW 750Li

Tiny

ZAKKATTACK

August, 17, 2007 AT 2:17 PM

1999 BMW 750il with a 5.4 12 cylinder. I did a tune up on it and now after the vehicle warms up it's making a ungodly howling noise down by the torque convertor area. But when you let the motor cool down and start it back up it goes away until it warms up again. What can this be? Is it something I did or pure coincidence?

FOUND 615 RELATED QUESTIONS

3 Answers

Tiny

merlin2021

August, 17, 2007 AT 2:40 PM

You might check for an air plenum problem.

Tiny

ZAKKATTACK

August, 18, 2007 AT 12:52 AM

So it might have a vacuum leak in the plenum? I'll definitely check that, but why would the noise be coming down by the torque convertor?

Tiny

Dr. Hagerty

August, 19, 2007 AT 11:09 AM

Could be the PCV valves on the back end of the plenum
(one on each side) it would make a sound like you described. To check this use a slack tube manometer at the crankcase, more than 6" of difference from side to side and that's where to start. Repost if more help is needed

Please login or register to post a reply.

Oil and Filter Replacement Subaru Legacy
Engine Oil Change and Filter Mercedes
Oil and Filter Replacement BMW M5 2005-2010
Brake Pad/Rotor Replacement