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Alternator Noise In Cab While Idle


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6Sixathome,

 

Did you ever get this issue resolved? I am having the same problem and the dealers are being uncooperative, although one dealer changed the alternator (thinking it was causing the whistling noise) and now the new one (DR37) is whining like crazy!! I've also got a power steering whistle/noise that is present when accelerating and cruising at highway speed. Check out my video on youtube and read through the description, sorry it's so long. I'm not happy and wish to get these problems resolved asap.

 

http://www.youtube.com/watch?v=XkJh4B7sk0Y

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Here's where I'm at with this, the first alt that I got was a DR37 (that's what's stamped on the case but is still 145 amp) and that one really whined so the dealer order me another alt (DR37, which the case of the alt is smaller than the DR44 and the pulley was almost 100 thousands smaller), which is what came up from using my VIN and the # off my original alt has been updated to the new alt, the DR37. OK now this new, new alt still has some whine but not as bad as the first new alt but is about as bad as my original alt. My original alt (DR44) is being rebuilt and I'll try that, I dont think the DR37 is geared correctly to be used on vehiles that came with the DR44 (If I'm wrong someone please set me in the correct direction, I'm no alternator expert) or something, but I'll know for sure when I get the DR44 back and try that. The video sounds exactly like my truck does, I also had my PS pump replaced and that is very quiet now.

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Thanks for posting an update 6Sixathome. I clearly remember my original alternator being a DR44...so I'm going to go back to the dealer tomorrow and see if they still have the old one (it's been a week since it was changed...so I don't know if they'd still even have the old one). I can't stand the whining...it's just too much. As far as the power steering noise, did your dealer just change the pump, or the pump and rack? You are so lucky to have such a cooperative dealer.

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I just had the most genius idea. I took a microphone and placed it in the engine bay, hooked it up to my laptop and recorded the power steering whistle (more like a constant hiss when the throttle is applied) and alternator whine while I drove. Then I placed the microphone in the cab and drove some more, recording the noise. Then I burnt the two recordings onto a cd and put it in the truck. Now when I take my truck into the dealer for the 5th time, they can hear it all loud and clear. Maybe THEN I'll get my power steering pump (or rack?) changed and I'll be happy with life again.

 

As far as the alternator, check your build codes in the glove compartment. If you have code "KG3", you have the 145 amp alternator. If you have code "KW1" you have the 160 amp alternator. From the factory, both alternators would have been stamped DR44 (Delco Remy) with different part numbers engraved in the top (25968616 for the 145 amp, 25877026 for the 160 amp). However, DR44 (25968616, 145 amp) has been replaced/superseded by DR37 (20881337, 145 amp...models 2010+). Another thing to note is the 160 amp alternator is only available (don't quote me on this) on the Tahoe, Yukon, Suburban, Escalade, 2500, 3500 and the snow plow prep package (VYU?). So after all is said and done, the DR37 should not cause a problem because it is used on all 2010+ 1500's. I think the problem is I got a bad replacement alternator that's noisy. This noise could be coming from too much of an air gap between the rotor and stator, or leaking diodes (that's what I was told by a shop that rebuilds alternators).

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The # stamped on my old alt is 25889451-145amp and the KG3 stamp in the glove box. I think the DR37's on the 2010+ trucks must have a different BCM or ECM program OR another built in noise filter because the odds of me getting two brand new alternators is pretty slim, I think. The guy that's rebuilding my alt looks like he's been doing it for a while so I hope the old alt (repaired) is the magic bullit, hopefully today I'll get it back.

 

SilverJet, what kind of truck and year do you have?

 

They just changed the PS pump and flushed the PS system.

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Phoned the dealer and they don't have the old alternator, it's been sent back to the manufacturer for warranty purposes. I have a black 2009 Silverado LTZ Ext cab, Z71, 5.3 Vin "0", loaded with everything but nav, only 10,000 km (~6200 miles). By going to the dealer, the only alternator I'm going to get is the DR37. If I replace it myself I'll have to settle for a reman DR44....which I shouldn't have to do....so now I don't know what to do. As far as I can tell from doing my own research and talking with an AC Delco parts store is that the DR37 has a different pulley size vs the DR44 (60 vs 57mm) and that is what could be causing the noise.

 

What noise was your power steering making prior to the change? Was it a constant "hissing" heard in the cab while applying the throttle/accelerating? That's what mine is doing.

 

I've never been so frustrated with GM service, and my truck.

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Phoned the dealer and they don't have the old alternator, it's been sent back to the manufacturer for warranty purposes. I have a black 2009 Silverado LTZ Ext cab, Z71, 5.3 Vin "0", loaded with everything but nav, only 10,000 km (~6200 miles). By going to the dealer, the only alternator I'm going to get is the DR37. If I replace it myself I'll have to settle for a reman DR44....which I shouldn't have to do....so now I don't know what to do. As far as I can tell from doing my own research and talking with an AC Delco parts store is that the DR37 has a different pulley size vs the DR44 (60 vs 57mm) and that is what could be causing the noise.

 

What noise was your power steering making prior to the change? Was it a constant "hissing" heard in the cab while applying the throttle/accelerating? That's what mine is doing.

 

I've never been so frustrated with GM service, and my truck.

 

The PS noise was kind of like a hissing noise, but more of a bad groan when turning the wheels and with higher RPM's. I got the call this afternoon that my old alt is rebuilt and ready to go, it needed a new rectifier, regulator and something else, he reused the DR44 case, pulley and the stator was good as well, I hope it does the trick, the cost of the rebuild was $128.40, not too bad if it gives me peace and quiet. You may have to bite the bullit and buy a rebuilt DR44.
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Since the dealer wasn't willing to cooperate with me, I decided to find a DR44 alternator. I called a local salvage place and they had one, low mileage for 100 bucks. So I went and got it and did the swap. The DR37 is smaller in size compared the DR44, the pulley's are different diameters (57mm on DR37 vs 60mm on DR44), and the windings are copper colored on the DR44 vs black on the DR37 (I would post pics but not sure how to do that). The "new" DR37 that the dealer put on does not spin very freely whereas the DR44 spins nice, smooth and quiet. After putting it on....I don't hear the alternator near as much. But today I listened for noises on my dad's truck (2008 Silverado LT Z71, 5.3L, 60,000km) and my brothers truck (2008 Silverado LTZ Z71, 6.0L, 110,000km)...and they both have the alternator whine just like in my video and the videos by 6Sixathome, and the whine on my brother's truck is actually the worst I've heard...and his alternator is a DR44, 145 amp. Sooooo.....I'm thinking it's the nature of the beast, GM alternators are just noisy. Period. But, the dealership (and GM) should not have put an alternator on my truck that is of a different style and different pulley diameter. I don't care if the part number for the DR44 has been superseded by the DR37...the pulley on the DR37 is smaller than the DR44 which means it will spin faster...thus creating more noise. AND I should not have had to spend $100 for an alternator from salvage and put on my practically new "under warranty" truck...just to fix a problem created by my GM dealer in the first place. Yeah I could take it back to them again, but all they're going to do is put on another DR37...which won't fix the problem. So, the lesson to be learned here is don't let the dealer change your alternator if nothing is wrong with it...and if you have an 07-09 GMT900 with a DR44 alternator...do not ever replace it with the DR37 but rather get your DR44 rebuilt instead.

 

As for the power steering noise, like I said I placed a microphone under my hood and recorded the sound on my laptop while I drove. After I played it back, it sounds horrible...all I can hear is a loud hissing noise whenever I apply the throttle (this noise even overpowers the sound of motor most of the time). So I was thinking, if I take it back to the dealer and shove a cd in their face with actual recordings of the noise...I'd better make sure I also have a recording of a truck that doesn't have the power steering noise. Well, my dad's truck doesn't have any power steering noise so I did the exact same thing with it, put the microphone is the same place and drove the same route. Then I played it back....and guess what....it sounds EXACTLY the same as my truck! So now I can't go with that plan of action because maybe nothing is wrong with my power steering pump. So now I'm really confused and think it could be something like maybe a problem with the sound deadener on the firewall or a rubber grommet that's not in place, letting more noise through the firewall than normal. But everything looks fine. :dunno:

 

Sooo, my new plan is to forget about the power steering and install a Volant Cold Air Intake...maybe that'll help mask the noise!!

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My PS pump is very quiet, as quiet as the new 2011 Silverrado that the dealer had on the lot (I went out and started it just to listen for alternator and PS noise, nothing just quiet) and I listened to another 2008 Sierra with the 5.3L and it's alternator (DR44) and PS pump made no noise at all, no whine, no buzz in the cab, nothing. I'm going to install the rebuilt DR44 as soon as I get it so I can check it out on the way home and hopefully it's quiet. What are you going to do with the DR37 that you have?

 

 

****I installed the rebuilt DR44 and it is pretty quiet, quieter than the DR37 but there is still a faint whine, which I guess must be normal, I can probably only hear it because I'm tuned into the noise, my wife could'nt hear the DR37 the other day while we were driving, but I could. So SilverJet your right, some noise must just be the nature of the beast. The two trucks that I listened to. I did'nt drive so maybe if I would of drove them I would of been able to hear it a little.

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I don't know what I'm going to do with it. I might put it back on and take the truck to the dealer and make them replace it with another new DR37 again, but I don't want that alternator on my truck...it's not the correct one. I could sell it I guess...or just keep it as a spare?? Like I said though...I would never put it on my truck anyway, I'd get the DR44 rebuilt. Funny thing is though, when I called to see how much the DR37 (#20881337) was...$484. So maybe I should sell it.

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