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-   -   Siren like noise (http://www.jeepforum.com/forum/f67/siren-like-noise-1542854/)

ingikarl 06-29-2013 04:11 PM

Siren like noise
 
Hi,
My 2008 WK CRD is making a siren like noise, following engine revs, particularly over the first couple of miles after starting from cold. The noise is not loud but quite distinct when driving up to ca. 40 mph. After that it is drowned out by other normal driving noises. I have had the turbine and alternator checked at a good workshop but the problem did not seem to be there.
This noise is very "pure" so to speak. The first time I heard it I thought it was from a police siren in the distance. The noise just stays there but fades when the engine is starting to get warm.
I have looked in this forum but not found an exact match. Has anyone had similar experience??

08hemi 06-30-2013 08:36 AM

Sounds like you could have a ground loop fault. Is it possible that the sound is coming through you speakers? You typically see this in aftermarket sound systems, but ive also heard of it being caused by the rectifier slowly starting to go bad and basically "leaking" extra current into the ground, which then flows up river through the grounds of your speakers and gives a rpm related whine. Might be a place to look...

ingikarl 08-04-2013 09:15 AM

Quote:

Originally Posted by 08hemi (Post 15623940)
Sounds like you could have a ground loop fault. Is it possible that the sound is coming through you speakers? You typically see this in aftermarket sound systems, but ive also heard of it being caused by the rectifier slowly starting to go bad and basically "leaking" extra current into the ground, which then flows up river through the grounds of your speakers and gives a rpm related whine. Might be a place to look...

Hi, thanks for the comment. The sound is present when the radio is off so I dont think it is coming through the speakers. Unless you think that the sound can be produced with the radio off. I am suspecting the alternator or a bearing in the alternator but I have not been able to verify that yet. The noise is clearly audible when the car (engine) is cold but almost disappears when it has become warm. Excuse me for not replying earlier. I missed your comment because there was no e mail alert. I will of course report back if/when I find the solution.

ingikarl 10-25-2013 04:47 PM

The latest on the siren like whine or whistle is that I had it check closely and the conclusion is that it comes from the turbocharger. But there are no fault codes and the noise just stays the same. Not sure what to do. Probably I will try to inspect the air supply and exhaust plumbing very closely for possible leaks or obstructions.

ingikarl 11-03-2013 11:26 AM

Bad turbo indeed
 
The result is a bad turbo. I looked at the air intake side after having removed the elephant tube and found that the blades of the compressor wheel were bent and damaged. Furthermore, there is play in the shaft. So, this one will have to be replaced I suppose. Will report on that when it is done. I have no idea how this happened. The car has never been subjected to harsh treatment of any kind and service schedules have been carefully kept. This is not good after only 54000 KM (34000 miles).:confused:

ingikarl 11-03-2013 01:05 PM

2 Attachment(s)
Quote:

Originally Posted by ingikarl (Post 17394722)
the result is a bad turbo. I looked at the air intake side after having removed the elephant tube and found that the blades of the compressor wheel were bent and damaged. Furthermore, there is play in the shaft. So, this one will have to be replaced i suppose. Will report on that when it is done. I have no idea how this happened. The car has never been subjected to harsh treatment of any kind and service schedules have been carefully kept. This is not good after only 54000 km (34000 miles).:confused:



Attachment 811410



Attachment 811426

BAH101 11-03-2013 02:41 PM

I wonder if your turbo ate a chunk of ice. It could have been last winter and it just caused some fracturing of a blade or two. Over time, the weakened blade came off causing the rest of the damage. I had a helicopter engine a few years ago ingest some ice, it also caused a howl at certain engine speeds. One of the blades had similar bending as your pic.

ingikarl 11-04-2013 02:56 AM

Quote:

Originally Posted by BAH101 (Post 17399106)
I wonder if your turbo ate a chunk of ice. It could have been last winter and it just caused some fracturing of a blade or two. Over time, the weakened blade came off causing the rest of the damage. I had a helicopter engine a few years ago ingest some ice, it also caused a howl at certain engine speeds. One of the blades had similar bending as your pic.

Well, it ate something I suspect. May have been something that escaped past the air filter after servicing. I have sometimes had to re-set the clamps that close the air filter housing. It is not such a good design either. But I will never know for sure.

ingikarl 11-20-2013 11:34 AM

I ended up having the unit replaced with an originzl new unit from Honeywell-Garrett. The total cost was $ 3100, which includes installation and all kinds of local taxes. I researched several other possibilities for rebuilt units, but considering that there is some warranty on the new unit, I decided to go for that.
I have the old unit. Will check if it can be sold at some small price for rebuilding. There is no end play in the shaft and very small diagonal play, so it should be repairable. The only visible damage is the turbo intake wheel with damaged blades.

MBDiesel 11-20-2013 03:32 PM

Quote:

Originally Posted by ingikarl (Post 15754859)
Hi, thanks for the comment. The sound is present when the radio is off so I dont think it is coming through the speakers. Unless you think that the sound can be produced with the radio off.

Even though you've found it wasn't the radio (and at this point I bet you wish it was!), I've found that the audio amplifier in the radio, at least with my REC unit, stays on when the ignition is on. Any alternator noise induced through the audio amp power supply would therefore continue with the radio "off". You can hear amplifier idle noise with the engine off and ignition on.


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