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BMW sounds like it is haunted

'04 BMW 330i. automatic, 99k miles (Wifemobile) Sounds like I have ghosts under the hood.

History:
3 weeks ago I replaced the gasket beneath the oil filter housing. Noticed that coolant had been slinging off the water pump pulley. No significant water loss. No worries, I will take care of it next time she is out of town.

1 week ago: “Honey, did all this water running across the parking lot come out of my car?”

This morning I replaced water pump, both thermostats, radiator, expansion tank, three hoses, fan clutch, tensioner on accessory belt, and several O-rings. After fifteen years of driving BMWs, I have learned that when you have to go in to the cooling system, you go all the way.

On restarting car, I have a whistling/moaning sound. Comes and goes randomly. Not related to engine speed other than perhaps it is a bit more pronounced on deceleration. Took a trip to the store, and after about 10 miles it quieted down to where I did not notice it. The noise was back when I pulled the car into the garage after washing it. It is loud enough that people turn and look curiously at the car at stop lights.

My theory: Head got pretty hot as we drove to gas station for water to get us home last Sunday. Perhaps that hardened the intake manifold gasket enough to make it leak? Idle is perfectly smooth, so if it is a vacuum leak, it is not yet a big one.

Any other theories?

Go back over everything and make sure you didnt crack any vacuum lines. They may look fine but if one has a crack now it will whistle/moan and WILL get more pronounced on decelleration. You had a lot of things undone to do the job you described so I’d go back over every hose to make sure everyone is tight and or not cracked. Esp the intake hose…and pcv hoses… Sometimes there are even “mufflers” on vac lines and hoses…like on a Honda to quell intake noise…makes sure all hoses are copasetic.

Blackbird

Honda…I haven’t heard the word copasetic (or copacetic) since my University days. It means everything is alright or satisfactory if you haven’t heard the word before. Nice way to upgrade the language on CT there HondaB.

Good suggestion. I had to pull on the air intake tube to disconnect the air filter, and I had to replace the rubber hood on the throttle body last year on my other '04 because it got brittle and cracked, I may have cracked this one. I will look.

Interesting that the word copacetic caught missileman’s attention. That word is so unusual that I remember distinctly the last time I heard it. It was 1974 and I was in Roachdale Indiana, and the speaker was Ashley Tharp.

A vacuum leak can easily be detected with a can of starter fluid. Withe the engine diling, simply spray a little fluid in the are where a leak might be. If there is one, the idle will mometarily rise.