Strange Noises

[leshart]

Bear with me here...this could take a while.

Started out hearing a noise that seemed to emulate something spinning (bearings etc.) when my pickup would downshift coming up to a stop sign or light. Always above 2500 RPM. Once it was below that I wouldn't hear it. It wouldn't happen every time either.

I'm a volunteer firefighter/first responder in a small rural area and received a page one day to respond to an auto accident. I'm headin' out the highway at a pretty decent rate of speed when the noise starts under acceleration...get's louder and then sounds like a repetitive "thumping" sound. This noise seems to be coming from the rear of the engine...sounds like it's under the dash on the passenger side. Sounds like the release of pressure or something.

So, I go to my local dealer and they tell me that the noise is because my alternator is bad. WHAT??? I don't have 60k on the pickup yet and the bearings are bad in the alternator? Yes, I know it CAN happen but I'm just not sure I wanna by that...nor spend 370 bucks on a dealer only item that I might not really need.

I doubt what they are telling me because the noise only happens when I'm driving, I can't make it happen sitting there...if the bearings were bad in the alternator, wouldn't they be making the noise ALL the time?

Any suggestions? I think I'm gonna go to the next little town over from me and see what their dealership has to say. On top of all this, it seems like my mileage has taken a pretty bad dump (256 miles on a tank of fuel pulling an empty 18ft flatbed)...my cruise control, all of the sudden, won't work when I'm under a trailer...hmmm

Sorry for the long post. It's my first one and I wanted to make sure that I got all the details out there and if you fellas have experienced or heard of this kinda thing I would really appreciate some feedback. This is my first Powerstroke...I've been a Cummins owner since '96...

Thanks so much~
Les

[wontonrunner]

If you don't even have 60,000 on the pickup then why worry. Its warranty...unless I am missing something here.

[elibenson]

First of all, Welcome to the 'org..

My F450 does something that sounds something like that. I think the problem with mine is a really filthy oily intercooler. If I get my speed up on the highway, or I get the boost up pulling a trailer, I hear something that sounds like a squirrel cage fan with a bad bearing. I turned off my A/C, radio, etc, and it only got more noticeable. It was not the A/C blower. It was directly related to the boost I was pushing. It only does it after a few minutes of driving with higher boost. I think the bottom tank of the intercooler is gummed up, and with some extra boost, some of that goo manages to get blown up into the vertical tubes in the intercooler. What I am hearing is the sound of that crap bubbling its way to the top of the intercooler.

Basically, I think my truck has asthma..

BTW, I think the alternator bearing idea is a load of crap.

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Last edited by elibenson : 11-02-2009 at 10:20 AM. Reason: hit save too soon.

[SANDSAILOR]

I'm also having a simular problem but mine only does it under light throttle, any thing harder that just grannying it wont do it. I can make it louder by modulating the trottle. If I let off it stops, if it barely touch the throttle it starts, if i give it some more throttle it stops again. I cant seem to trace it down because it wont do it parked even when reved up.

[leshart]

Well, it makes me feel a little better knowin' that I'm not the only one with this stuff goin' on.

If my warranty covered the alternator, I would just let 'em put one on and then take it back to tell 'em that didn't work...lol..but that's not the case.

Thanks for the welcome, Eli...I appreciate it. Sounds like yours is doin' exactly what mine is.

btw...the cruise control worked today under a 32ft. gooseneck, so I guess it's intermittent function has nothing to do with a trailer.

I did do something today that I hadn't done. I mentioned that it wouldn't make the noise sitting still...I shifted from drive to neutral and mashed on it...here came the noise. Strange stuff.

Under power it seems to do it around 2500 and as soon as I let off the throttle, or it shifts gears, it stops instantly. Problem is it's unpredictable...won't do it every time.

If I can get it to another shop and have them start lookin' in a different place, then maybe I'll figure out what's really up with it.

Thanks so much for the replies. If anyone else has any ideas, please share them.

[wontonrunner]

Is it possible that the sound you are hearing is either the turbos winding down or the cooling fan slowing down or speeding up depending on what the rpms are.

Because with my truck, and its more noticeable stock than tuned, if you are on and off the throttle than you get a whirring sound which has always been normal and to me sounds like the turbos or the fan.

Its not the turbo whistle I am referring to, it is more of a low whirring/hum and happens at almost any rpm but is more noticeable at some rather than others. Also, you won't hear it when in park or neutral because the turbo will not build boost unless loaded. The turbos are located on the passenger side near the dash so it could be this you are hearing.

[SANDSAILOR]

Mines not the normal turbo sound, it could be a bad turbo I suppose, I've had my truck tuned for the last 6X,000 miles and this is a new issue.

[SANDSAILOR]

Well I just decided to look up the sounds of bad turbos on youtube, well not all of them sounded the same but there where a few that sounded almost exactly like my noise issue. I know the high presure turbo is prone to going out so that maybe my problem after all, I guess that better than a HPFP going out and a lot easier to swap out. The down side is its a more expensive part.

[leshart]

Yeah, mine's definitely not a cooling fan sound or anything like that. I can hear all those things and, although the cooling fan does roar, that's not what I'm hearing.

And then there's the "thumping" sound...I am beginning to really believe now that it's something turbo related.

I have to go out of town this weekend, so I'm hoping that I can get my pickup into another dealer next week. I'll report back their findings...I'm sure it will have nothing to do with the alternator...lol

[SANDSAILOR]

I had a interesting drive home today, my tea pot sound went from being here and there depending on throttle possition to constant and even at idle while in gear. It wont do it in park and now I'm not so sure its the turbo, I know I have a exhaust leak under the hood somewhere and it may just be that and it got worst today. Im hoping its just and up pipe leak.