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That does not sound good. Pull the engine covers off. And pick up a stethoscope type listening device. See if you can isolate where the sounds coming from. I would not rev the engine like that anymore. There are a couple of big timing chains in the engine. If one of them is acting up and you throw it off a sprocket. Your looking at major repair. On the other hand it may be as simple as the fan hitting something. How many miles are currently on the vehicle? Towards the end of the video the sound gets louder. Almost like exhaust leak. Do you have the factory exhaust system still on the car or did you modify it?
 

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Discussion Starter #3 (Edited)
Hello Rick

The miles of the car is 68350miles, no its the original exhaust still.

A time ago the serpentine belt went off and they changed the whaterpump att the same time, before the serpentine belt went off they didnt have this problem with the car...

Do you think its the timing chain?
 

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Ibra,
That's just a thought on the timing chain. It's too hard to tell by the video. But it's making a alot of noise. How long after the water pump was replaced did the sound start? Knowing that the water pump was replaced I would remove the front covers from the engine. And inspect all the pulleys and idler bearings. The covers come off pretty easy. They are just held on with the rubber grommet and friction pins. So just give them a slight pull up and I'll come right off. There's a shroud between the radiator and the fan. Just unscrew the four or five fasteners and that will lift off. This will give you a better view of the front of the engine. And will keep the noise from bouncing around. Make sure the belts are running smoothly. And all the bearings are not wobbling. There are a lot of things on the front of the engine that turn around. Besides the water pump. at 68,000 miles I would think it would be a front engine bearing on one of the pulleys before I would think it was a timing chain.

I know this is not much help to you. But this is where I would start if it was my car. When I changed out my water pump I replaced all my idler tensioners and pulleys at the same time.

Here are some parts listings from www.realOEM.com I just used a 2004 BMW 760 add to your Vin number to get exact part numbers.

http://www.realoem.com/bmw/enUS/showparts?id=GN83-USA-12-2004-E66-BMW-760Li&diagId=11_3358

http://www.realoem.com/bmw/enUS/showparts?id=GN83-USA-12-2004-E66-BMW-760Li&diagId=11_3359

Here's the belt drive vibration dampener. They make noise when they start to go out.

http://www.realoem.com/bmw/enUS/showparts?id=GN83-USA-12-2004-E66-BMW-760Li&diagId=11_3359

Here's the radiator cover I'm talking about removing. It's right on the front of the engine over the radiator. This will give you a better look.

http://www.realoem.com/bmw/enUS/showparts?id=GN83-USA-12-2004-E66-BMW-760Li&diagId=17_0258
 

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Discussion Starter #5
Thnx Rick.. the sound came right after the serpinetine belt snapped and had to change the waterpump so the sound and the serpinetine belt snapping are connected somehow
 

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That would indicate to me that something else in the belt driven system has gone out. It may also be that the mechanic didn't assemble the fan clutch assembly back correctly. It may have come loose and is touching the shroud.As difficult as it is to get to this stuff. Bring it back to him/her. If it does happen to be idler pulley or tensioner. Just replace all of them. It's a little early for them to go out. Usually they last to 100,000 miles but it's not unusual. I doubt it's the vibration dampener. But you will see it wobbling if it is. That one is very difficult to get andremove/replace.

And if you haven't seen this please add your name the list I've started. Trying to find out how many 760 the owners are still on the fourm.

http://www.bimmerfest.com/forums/showthread.php?t=925639

Rick
 

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Sounds like the plastic pressure hose from the AIR pump to the diverter valve is broken. The noise you hear is the exhaust pushing back into the valve.

It is possible that the hose was broken or not clipped on to the diverter valve in the process of replacing the water pump/drive belt. The pressure hose must be moved slightly to replace the water pump.

If you remove the right air intake tube and front engine design cover, look straight down under the vacuum pump and you will see the plastic tube. It is "Y" shaped and goes left to right.

Mark.
 

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Sounds like the plastic pressure hose from the AIR pump to the diverter valve is broken. The noise you hear is the exhaust pushing back into the valve.

It is possible that the hose was broken or not clipped on to the diverter valve in the process of replacing the water pump/drive belt. The pressure hose must be moved slightly to replace the water pump.

If you remove the right air intake tube and front engine design cover, look straight down under the vacuum pump and you will see the plastic tube. It is "Y" shaped and goes left to right.

Mark.
Great catch. That's why asked about exhaust. I didn't think the air pump leaking could be that loud. But I've never disconnected mine while it was running.It sounds horrible at the end. But what you say makes perfect sense. I hope that's all it is for his sake.
 

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When I bought mine it was sounding quite similar to yours, also the previous owner had the serpentine belt snapped and waterpump changed. It was cylinder 7-12 exhaust cam that had jumped a few teeth. I found that if intake sounds rough and/or get hotter than the other it is a good chance that the timing is wrong since exhausts gases enters the intake assembly.
Thomas in Umeå / Sweden
 
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