I have started to hear a chirp when I start my "02 K3500, 8.1L. It only happens on cold morning startups.

I am seeing some rust tracking near the upper pulley next to and just under the alternator. I have a newer belt on this truck and it already has some rust tracking on the outside (back) edge.

I am wondering if this idler is getting ready to go south. Or is there a problem inherent with these engines that I am not aware of.

Also, are these idler pulleys a warrantable item if the extended power train warrenty is in effect?

"Doc"

I have the exact same thing, and they have replaced the fan belt, and it still does it. It stops when it warms up. I guess I will see if something breaks. I only have 10,000 miles on it.

Duramax:

Do you have any rust tracking near any of the pulleys? I have some near the pulley just under and next to the alternator.

I also have a slight hint of antifreeze, but it does not check out with a pressure test.

"Doc"

I don't know about the rust streaks, because I have not checked that. Do you smell antifreeze, or see in on the belt. If you smell it, look at the drivers side head above the spark plugs in the middle, there is a plug there. More than likely it is seeping. Mine was, and I tightened it with a 3/8s drive ratchet.

Good Luck.

Throw some sand or metal shavings on belt (with engine off), sometimes these belts will get a "glaze" on them and they'll chirp. Air cleaner will keep sand (or shavings) out of engine. Coolant leaks will usually keep belts singing all the time.

This is an image of the rusted area that is on my truck. Also there is a weird pattern on the pulley under the alternator. I didn't notice it until I took the photo. It looks to be black on part of the pulley and rusted on the rest. This belt has less than 10,000 miles on it and it looks like it is due to be changed again. Is there a problem with belts on the 8.1L engines?



http://img.photobucket.com/albums/v307/photog101/IMG_1591.jpg (http://img.photobucket.com/albums/v307/photog101/IMG_1591.jpg)
(Image has been resized. Click it for full size.)

(Image has been resized. Click it for full size.)


"Doc"

I got it too...the noise...only 1st few seconds.... Only had truck for a few months and notice its worse with cold temps. We'll see how it goes as we enter winter. Please post if a solution is found. Dealer changed my belts just before I picked it up.

I'm glad mine isnt the only one.:D . I inspected the belts,there fine.My truck sat for at least 6 months,so there was rust on all the idlers and pulleys,its almost all off now,but I thought that was why,until now.

I looks like you may need to replace the belt tensioner because it looks like it must be bouncing and letting the fan belt go slack. JMHO-

Photog: Not sure if you figured yours out but I was searching GM TSBs (tech service bullitens) and ran across what I believe is the noise I am experiencing.

TSB #PI00856A-(04/08/2004) describes subject as:
"allison LCT1000 Oil Pump Whine, Buzz on cold start".

The condition is described as:
"...transmision may experience a whine/buzz type noise that occurs after 15-45 seconds (approx) after cold start and will last 15-30 seconds (appox). The noise may be present after the truck is parked a minimum of a overnight cold soak. The noise will not return on hot or short term restarts"

No recomendations are made....the noise is explained by folks at Allison as "...air moving out of torque converter through cooler circuit and lube regulator valve and into suction side of oil pump. This noise condition DOES NOT contribute to durability concerns..." and goes on to say "NO repairs should be attempted to eliminate the noise."

They musta fixed something cause it only pertains to 01-04 models.

This sounds like my noise...although mine begins nearly immediatelly after cranking stops and engine is now running. Lasts only a few seconds. Other than that...exactly as described (after cold soak only etc). My truck had 36,000 on it...its a 2002 8.1L/Allison.

I had an 01 8100 and the allison whined a lot. I traded it because I was afraid it would leave me high and dry. My 06 doensn't seem to do that. I don't have any rust on my pullies like the picture shows. Someone mentioned the chirping being caused by the idler bouncing up and down releasing tension briefly. That could be it. Maybe we need a stronger tension pully.

Do a search on the squeaky belt saga. I have had alternators, belts, pulleys, belt tensioner pulley, ac belt, ac pulleys, everything, it always started with cold start chirp, then over time it would get worse to where it would take 20 minutes to 1 hour of driving before it would quit. With all these fixes, it would always come back. The only fix I have found is replace the stock belt with a GoodYear Gator back belt. I got mine at AutoZone for about 30 bucks, 20,000 miles and two winters on the belt, and have not heard any belt noise. With all the other fixes the dealer did, it was always back within 2000 miles. They did also replace belt about 6 times with GM oem belt.

Obviously two different scenerios (belt squeel common to nearly all GM truck engines ((5.3 etc...)) and the tranny pump buzz I am experiencing).

I too have heard that the belt squeel can be fixed with a high quality aftermarket belt. One thing people often overlook when replacing the serpentine belt is the smaller belt behind it...cant remember...power stearing or something. I've heard of folk replacing the serpentine belt and squeel remains. Then they replace the smaller one and it goes away.

Anyone else think they have the tranny oil pump noise? I might search under "Allison OEM" threads to see if people speak of it there. Hope I didnt chime in with something becouse I misunderstood the original posters symptoms...sounded like what I might have.

mr udy, mine has the allison chirp when cold, sounds just like the tsb. It only lasts maybe 30-60 seconds and only does it on cold mornings the first time it's started. 95,000 miles and no problems so I don't worry about. I've gotten so used to it that now I listen for it as a sign that everything is normal.

Mr Udy:

That might be just what I am hearing, as I feel a slight vibration through the floorboard while the squeeking is happening. It does sound like it is coming from the engine compartment though. What I am hearing might be considered as a hydraulic noise but more like a squeal. It only lasts for about 5 seconds and never reappears until the next cold soak.

I was in a rush this morning and did not even notice it, but since it was cold and I was more worried about keeping warm, I probably missed it. Normally I hear it every morning since the temperatures have dropped.

I guess that I will wait until tomorrow morning and have someone crank the engine and see if it is more toward the rear of the engine or transmission / converter area. I have two guys coming over to help me stretch my tonneau cover back because some kids came over and unsnapped it two nights ago and it shrunk so that I can't get it by myself. I'll put a couple of 500 watt lights and a 1000 watt heater inside the box before they get here and before we start tugging on the cover, I'll have one of them hit the starter.

Thanks for the heads up.

"Doc"

Photog101: I'd admit mine sounds like it comes from the engine compartment too....same thing...like 5 seconds or so. Also...longer/louder as it gets colder lately. Could be cause engine compartment less insulated than floor...so it just sounds like its from there. Let me know what you find with your friends. Hard to start and have your head under truck at same time! Remote start would be handy.

I have not been overly worried especially now that GM/Allison sais it is not a "durability issue". 8100HD reports he has it with 95K on his although he reports 30-60 seconds of noise. Heck, GM said infamous "5.3 Piston slap" isnt a "durability issue" either...sounds absolutelly horrible in my wifes Yukon with 110,000 miles but runs like a top, stilll has good power, and uses no more than 1qt of oil over 3-4000 miles. So...I'll trust GM (Allison actually) a bit on this one although, in my field, you learn quick that everyone covers there own ars and knowone wants to admit there is a problem, or worse yet that they own the problem (responsible for) and the warranty costs associated! I wonder what Allison did after 2004 to alleiviate the noise? Any Tranny guys/rebuilders out there know?

8100HD: how long you had your truck? Does the noise get longer with age/mileage? Mine is only litterally like 3-6 seconds or so....Id be surprised if it even went 10 seconds. I just got mine in the fall with 36K on it though...so I'll see if it gets longer with colder temps and as years/mileage progress.

Mine has made the cold start chirping since day one, once warmed up it goes away. No problem other than the annoyance.

DEWFPO

Mine has made the cold start chirping since day one, once warmed up it goes away. No problem other than the annoyance.

DEWFPO

Is your chirp the trans noise or the belt noise. Mine has always done trans noise at a 30 or below start up, it only lasts about 3 seconds at the most, and to me it sounds like a hydraulic pump as it is almost cavitating for a second before the fluid gets to it. I think the thread got changed around from the original post. I got rid of my cold start chirp by replacing the belt.

Is your chirp the trans noise or the belt noise. Mine has always done trans noise at a 30 or below start up, it only lasts about 3 seconds at the most, and to me it sounds like a hydraulic pump as it is almost cavitating for a second before the fluid gets to it. I think the thread got changed around from the original post. I got rid of my cold start chirp by replacing the belt.

Mine is belt noise.

DEWFPO

I think that I have finally located the noise. When the engine started, it seemed to come from the lower front section of the engine compartment ... near the radiator. However on further inspection I crawled under the truck and it sounds like it comes from the torque converter area. I guess that it is the transmission issues that was described above.

I do notice that even after it is warmed up, that if I pay attention to the torque converter area, that there is a small sound that I can identify as being similar to the original noise, but it is almost non-existant.

I guess that I will just live with it ... that is until the next truck. I'll be looking for this type of problem.

"Doc"

I am not too worried by it. Gonna do some more research on it. I'd like to see if there are any long term problems associated with the noise despite GM and others saying its not a durability issue. I also want to know what was changes in '05 since TDB only covered '01-'04 Allisons. I'll post back what I find. Until then...

I am not too worried by it. Gonna do some more research on it. I'd like to see if there are any long term problems associated with the noise despite GM and others saying its not a durability issue. I also want to know what was changes in '05 since TDB only covered '01-'04 Allisons. I'll post back what I find. Until then...

Please do let us know what you find, I would be interested on what you find. Thanks

I have the chirp sound and it goes away after about 20-30 min. Or when warmed up. Can't seem to locate where it is. If it were the pulley or belt wouldn't it chirp all the time? If it stops after it's warm, wouldn't it be something like an intake leak? I was thinking like a suction chirp. Just tossing that out there. I'm hoping all it is, is just a tension pulley. Easy fix there.

michcruiser:

Like I stated before, I thought that it was coming from the engine compartment. However I got under the truck and put my hand on the bell of the transmission and it seemed that is where the noise is definately coming from.

I checked with a GMC dealer and they said that there was no need for concern in the "01-"04 models. I asked what the difference was with the "05 and no one seemed to know. I guess that I will have to get with an Allison dealer to get the real scoop. I have two Allison shops here in my area and at the first chance that I have, I will be at their door and asking pointed questions.

Might not be to far in the near future, as I am due for a transmission service.

"Doc"

Doc, Yesterday I was running on about 2-1/2 hrs sleep. I got to thinking about it more this morning. I'm out in left field on my last post. If it where an intake leak it would speed up and slow down with the engine speed and it does not.

If it stops raining today I'll crawl under mine too. There is no Allison dealer around here. Hope you get to find out from them.

Mr. udy, I should probably clarify. When I say 30-60 seconds, it's not constant. Usually it will take 5-10 seconds for it to start, then it will chirp a couple of times, pause, chirp again, pause, so on and so forth. This entire process will last 30 seconds, if extremely cold it will go on a bit longer. I got the truck when it had 26,000 on it. I would be surprised if your noise increased, mine has stayed the same, as best I can remember since I've had it. Like I said earlier no problems at all with the transmission. For that matter no problems with the entire truck, but I finally had to put a crank position sensor on it last week at 95,400 miles, and that is the first one of those.

8100HD...thanks for explaination. Yours is a good example for me to not be worried (you've had it for many miles).

I've heard the crank sensor is common with the 8.1Ls....:(

Is the chirping your all talking about a kinda of sqeeking noise? Or are you talking about belt slipage?? Because The 2002 8.1 2500HD/ allison, I just bought... is doing it all the time. It's kinda like a lite sqeek sqeek sqeek while driving or idling and gets faster with rpm's . Is this something different then what your all talking about....Or should I worrie about it??

Nitronut:

I think that if you read the whole thread, you will see that we have been describing a short term noise that only happens when cold and at initial start-up.

If yours is constant, you possibly have something other than what we have been discussing.

I have relinquished myself to the noise comes from the torque converter area on startup and supposedly that is nothing to be concerned about. The two people that I used to know when I was in the mechanic trade; are now retired. I am looking for a competent automatic transmission mechanic with Allison transmissions. At that time I will be asking some very pointed questions as to the difference between the 2001-"04 and the 2005 models.

"Doc"

Thanks Photog101..Now I am really wondering what it is. You really hear it when you are next to a another car driving or stopped NOTE...I am not trying to highjack this thread..

Thanks Photog101..Now I am really wondering what it is. You really hear it when you are next to a another car driving or stopped NOTE...I am not trying to highjack this thread..

That is what mine did all the time until I switched to the goodyear gator back belt.

That is what mine did all the time until I switched to the goodyear gator back belt.I did some checking. And
your rt it's my belt. The gator is going on tomorrow