"Chirp" w/ dual alternators

[DocDyno]

Hey all with dual alternators.
Following mdrag's superior instructions and parts lists and contributions from many others, I recently installed a second alternator on my '02. I purchased the official GM brackets and bolts as well as the GM Belt specified for the '02. I used the Powermaster (like mdrag) unit for my addition and mounted it in the stock location. Did the wiring and it works. The belt tensioner seems to be residing within it's designated marked parameters However I have two issues: (1) When I key-off I get a chirp. Sounds like belt noise. I am concerned that it may prematurely wear the belt that took me several weeks to get (special order). Anyone else with similar issues/solutions? (2) Randomly upon several occasions the "BAT" light will flicker on for a couple of seconds then off. Has only done it 8-10 times. The voltmeter doesn't fluctuate so I think it is only an indicator light circuit issue, not a charging fault issue. I double checked for a backed-out pin on the ECM- seems OK. Any thoughts or experienced feed back would be welcome.

[redmax]

DocDyno,

I also added a second alternator (180 or 190 amp, I do not remember). I also get a chirp when I turn the truck off. It did not do it at first, but lately it does it every time. I only have a little over 2000 miles on the truck. Rarely driven. I have never had the Bat. light come on.

redmax

[mdrag]

DocDyno,

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=003007&p=

I have the enhanced belt squeal at shut down option as well with the dual alts. Same experience as redmax - not initially there but now does it darn near every time I shut off the truck - less pronounced when the engine is cold. I haven't tried anything to see if I can make it go away. As far as how this will affect the serp belt longevity????

2DAMAX posted a similar problem with the battery light flickering after installing the dual alts:

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=002303&p=

It seems his problems just went away, and I don't remember reading anything further on this problem. I've not had any problems with the dual set up - no BATT light flickering at all. Since you have already checked the ECM terminal, one of the other suggestions in the above link was checking the battery/alt connections and make sure they are secure.

After I had my aftermarket alarm installed (and before the dual alt install), I was getting an occasional flickering of the BATTERY AND SECURITY lights. All the battery connections were tight - drove me nuts. Finally, I noticed the alarm installers used those battery tap connectors on the battery cable connections, and the bolt was too long on the ground terminal PS battery. Even though the bolt was tight, the cable would wiggle slightly making intermittent contact. Replaced with a shorter bolt and no further problems.

You mentioned mounting the Powermaster alt in the stock location - just to clarify - is the PM alt mounted on the PS or DS?

[Maverick]

My 3500 chirps all the time when I shut it off. I only have a single 130. It has done this for the last 57,000 miles. My 2500HD doesn't chirp at all.

[odoh]

Doc ~ Would you happen to have the PN handy on the serpentine belt for the '02s? Much obliged. ~ odoh

[ 04-16-2002: Message edited by: odoh ]</p>

[odoh]

You fellas w/the chorus of chirping alternators ~ Did you install the High Output alternators? If that is common to all, it could be from the increased rotating mass upon engine shut down wanting to continue rotation briefly. That would account for chirping when warm and belt (friction) is softer. ~ odoh

[ 04-16-2002: Message edited by: odoh ]</p>

[mdrag]

odoh,

My 3500 squealed occasionally on shut down BEFORE the second alt was installed. My second alt is a Powermaster 200A unit. Most likely the longer belt and additional accessory magnify the problem.

IIRC, the '02s have a different serp belt routing than the '01s, and the problem seems to be occuring on both models...

I've gotten used to the squeal, and it really doesn't bother me.

[DocDyno]

Odoh
Belt part number for the '02 (w/ dual alternator option) is 97300655. I got this number from a friend at GM engineering. When I went to order it I was told that the number was not a "good number" After additional research, the parts department was able to place the order. It seems the part number had not made its way into the system as of my order date ( mid-February) This IS a good number.

[DocDyno]

mdrag
Powermaster is mounted on the passenger side (PS). I thought I might try to quantify exactly where the chirp originates. Idler, tensioner, alternator, etc. At this juncture, I'm not sure how that will help me alleviate the noise, but it might establish a direction.

[bmoeller]

I just finished the install proces, worked well, thanks to the detailed information available on this site. I used a 130 Amp alternator, no chirp yet (3 days). Having the belt number enabled the parts people to get it for me in 3 days. TYhanks again to those who have given us such good information.

[RONCLYDE]

I as well as MDRAG have chosen to install the audible SERPENTINE BELT IN PLACE device with the second alternator. Instead of always opening the hood to check if the belt is there we now have the convience of checking it without leaving the cab. I was informed that it comes from the alt pulleys and belt contact area. the alternator has the mass from the rotor turning and when the engine shuts down the rotors want to keep going and thus producing the noise. They claim it has no adverse afects on the rotor, pulley or belt. I have seen and heard a lot of this on emergency vehicles that run dual alternators. the larger the alternators or even the load on them at shutdown affects the noise. The chirp is usually quieter with low loasd that for say at night when the headlights and heaters are on. just my 2cw.

[odoh]

Doc ~ Much thanks!

Ron ~ Sounds reasonable. No doubt a good call

odoh

[ndamico]

I just took delivery of my 2002 2500HD CC D/A about 1500 miles ago. It came with the dual 105 amp alternators. it just started doing the chirping thing recently. it also DOES illuminate my battery light on the message center once in a while for about 5-10 seconds. no change in voltage meter and no pattern in what i am doing in vehicle. it has happend when cruising at 35MPH or stopped, or coming to a stop.

also, i tried to lookup my ECU on "http://vci.ecomm.gm.com/vci/" and it said VIN not found. any ideas there?

Thanks

nick

[odoh]

Hmm, reading some back threads confirmed the serpentine belt (PN 97300655) for the 02's that DocDyno had provided at my request ~ but there was a caveat by RonClyde (I believe) deep in the thread about that PN being for Non-CA emission vehicles. In that mine has CA emission, this of course raises a question. :confused:

Is there anyone out there w/a CA emission duramax w/dual alternators? If so, would you confirm the serpentine belt PN ? TIA ~ odoh

[ 04-16-2002: Message edited by: odoh ]</p>

[IndigoDually]

I had a truck with a single 200+ amp. alt that would cause the belt to squeal when cold. I believe that under load the alt. requires a lot of torque to turn it and when the belt was cold it would slip until it warmed some. Kind of like the belt was loose though it wasn't.

Anybody getting a squeal when cold with intake heater on and batteries trying to recover from starting? I wonder if there is less tension on on of the alts. due to configuration of belt routing and the distance from the tensioner? Just an idea. Does the belt wrap around the pulley the same amount to give it similar belt contact surface?

John

[NJDMAX]

I havn't gotten the belt squeal when cold-(I have dual alts. from the factory)but I do get the "chirp" when turning the truck off. Happens when the engine is at operating temp.There was a post awhile back about this and it seems to be a normal thing. It did it from day one on mine.

[ndamico]

I have a 2002 Duramax with factory dual 105A alternators..will check the serpentine belt p/n and get back.

[odoh]

Nick ~ Thanks. The aux alternator is the one on the drivers side of the eng compartment.

I'm not too far from Sac ~ actually Newcastle, near Auburn. Were you able to find your DuraMax locally? If you wish, you may email me odoh1@hotmail.com ~ odoh

[ 04-16-2002: Message edited by: odoh ]</p>

[odoh]

Bump

[ 04-18-2002: Message edited by: odoh ]</p>

[ndamico]

Hi,

i can't seem to find any part numbers on my serpentine belt..it looks like they are worn off perhaps? can that happen in 1700 miles?

[ndamico]

CORRECTION!

After cranking the engine a few more times, I found the following part # 97300657 WAD 6PK3476. My truck is CA emissions, with dual factory 105Amp alternators. I hope this helps!

[odoh]

Major THANKS Nick. You're probably the only one or possibly two in the state to have that as a factory installed option. Me be happy!

Thanks again ~ odoh

[rberner]

I have factory dual alts. and have no problems with squeaks or batt. light coming on.

I have just over 14,000 on the truck with the last 10,000 miles on a trip to Guatemala for the winter.
Love that truck tongue.gif

[AlaskaDmax]

Forgive me for the following stupid questions...
1) Is the dual alternator set up standard or an option?

2) Why would you need two alternators?

[mdrag]

AlaskaDmax,

The dual alts are a factory option, but can be added fairly easily. It seems the dual alt option is not well known to most dealers...I orderd my truck and never heard of the option until I read about it on this forum.

Why? I had a 200A Powermaster alt removed from my old Suburban just laying around, found out it was easy to do... Besides the oem 105A Delphi puts out about 60A at idle...MORE POWER!!!!