1988 744 Ti M46 160K

My son called today and said his car was making a whistling sound that did not start until it reached operating temperature. I told him to drop it off after work and I would swap cars with him.

When he arrived I was surprised how loud the sound was. It is very definitely a whistling sound and rather shrill as well. I did not have the time to look into it tonight beyond determining with a length of heater hose that the sound is coming from the area around #4 runner on the intake manifold. The car has a definite miss at idle as well, and he reminded me again that it does not do it before the engine reaches operating temperature.

This car has 10K on a replacement headgasket job. Of course the intake manifold gasket was replaced as well.

Anyone want to offer a guess or perhaps an actual experience with something like this? Thanks.

Randy