2nd Gen Non-Engine/Transmission siren sound

[dvieira]

siren sound/PROBLEM FOUND!!!

hi...



lately I have been noticing a siren type of sound underneath my hood. It gets louder as I give it more pedal. It is not my turbo.

I checked to see if it was my vacuum pump inlet port by diconnecting the vacuum tubing and plugging the port.

Could it also possibly be the altenator bearing shaft.



Thanks,



DaveOo.



the problem was a loose clamp on the boost tube, next to the intake, called Cummins West, they suggested the cause for the

siren sound, DUH!!! on my part, went out and tighten clamp,

it was loose, will see about noise on way home from work tonight.



thanks



dave

 

[illflem]

Check the alignment of the tensioner pulley. Sometimes the pulley will be fine but the pivot worn causing the belt to ride up on the side of the other pulleys causing a whistle.

 

[rspinks]

Could you describe the noise better? I've had a medium to high pitched woo-woo-woo sort of sound since new with my ETH. The tone sounds very much like the whine produced by a roots-type supercharger on a gas motor. From poking around with a stethoscope it seems to be coming from the top gear in the gearcase.



I've got 10,000mi now and if it's still doing it at 20k I'll start worrying about it more earnestly. I took a sample from the last oil change but haven't sent it out yet, hopefully it doesn't come back with any abnormal wear particulates.

 

[dvieira]

well i checked the pulley as illflem suggested, idle and goosed the throttle, idler wheel was running straight, not saying it didn't under heavier throttle, but the siren sorta sound is coming from the driver's side of the engine, and it starts off after i take off from a stop, and gets a louder pitch till i'm at crusing speed then stops. this is driving me crazy, thinking of putting my egr stuff back on and taking it to the dealer.



thanks



dave

 

[Ram4Sam]

gear whine

RSpinks, I chased that noise when I first got my ETH almost two years ago. Your description of the noise is exactly how I would describe it. I think it is in the drive gears for the power steering pump/vac pump assy. The dealer will call it something like "normal 24valve gear noise" and probably do nothing. At the time, I test drove four other ETH's from two different dealers, one was quiet and the other three did it to various degrees. A good friend who works on the diesels where I bought mine said that most of the ETH's he has seen make this noise. I think that the gears aren't a perfect match hence the noise. I did an oil analysis at 10,000 miles and again a few weeks ago at 20,000 miles and they both came back clean. Mine has quieted down some as the miles pile up and since the oil tests have been okay, I don't think anything bad is happening. One thing I did do was take it to the dealer for the first oil change(it was free) and complain about the noise. Of course their diagnosis was "normal 24valve gear noise" but that put my complaint and their diagnosis on the record, so if it blows up before the 100,000 mile warranty is up, I can say I brought it to their attention when it was new. Hope this helps.



Sam

 

[rspinks]

Sam, I'm really glad to hear your input. After several posts and many other inquiries there's only been one other TDR fellow that said he had the same noise and it went away gradually on his truck.



I can hear the tone on other trucks to varying degrees and mine is certainly louder than normal, however two Dodge and one Cummins mechanic couldn't or wouldn't admit to hearing it. It is most noticeable when idling in a concrete enclosed area like a drive-through bank machine stall, the concrete seems to reflect that tone and make it much louder.



I'm gonna send the oil analysis in tomorrow, if it doesn't show abnormal gear wear particulate then I'll stop being concerned. After poking around with the stethoscope I'm quite certain it's gear mesh noise, in particular the top gear which I think drives the VP44.