Jake braking noise on a 2003 GMC Envoy

Discussion in 'GM Powertrain' started by carpem1, Jan 11, 2010.

  1. carpem1

    carpem1 New Member

    Hello Folks,

    I might have a good one for you all. I have a 2003 GMC Envoy SLT (4.2L V6 4x4). I brought it into a dealer this weekend and amazingly they said they have never heard of this. Since they want to charge me about $500 just to look at it further I wanted to check the experts on here.

    The problem only occurs when I am driving and its pretty straight forward. When I am driving the car and let off of the gas a loud 'glunk' noise happens. This noise is immediately followed by what can best be described as a semi truck jake braking. Even the dealership guys agreed with me it sounds 100% like a truck jake braking, but have no idea of what it is. The noise is louder the faster I go, but only happens when you let go of the accelerator.

    I took a look at it yesterday with a mechanic friend of mine. He also isn't sure what exactly it might be, however he thinks it might be the chain that powers the transmission. Since this would be a pretty extensive tear down, I wanted to see what others think first.

    Thanks, Carp
  2. Greg84

    Greg84 Rockstar 100 Posts

    Not sure what you mean by chain that powers the transmission.. there isn't anything like that!

    Can you tell the general area where the noise is coming from? Like from the rear, or more towards the front?

    One thing you can do to eliminate (or indicate!) the engine as part of the problem.. It sounds like this happens when you're coasting to slow down. Get to an isolated area where nobody will be behind you, get up to a speed where it happens and move the gear selector to neutral. Don't push the button on the side of the shifter in, it'll only let you go between drive and neutral so you can't accidentally put it in reverse. See if it still makes the noise when its coasting in neutral. If it still makes the noise, you at least will know the problem is from the transmission and farther back and that the engine and torque converter have nothing to do with it.
  3. smccollamjr

    smccollamjr New Member

    pinion bearing??
  4. carpem1

    carpem1 New Member

    Turns out I talked with another dealership today and the tech guy said the same thing happened to his wife's GMC a while back. Said it sounds like the world is coming to an end and all I need to do is have the fan clutch replaced. I also heard this from another person today on phone that they think it is the same part failing. Something to do with it not communicating with the vehicles computer properly which causes the device to suck in way too much air in, thus creating a sounds like jake braking.
  5. carpem1

    carpem1 New Member

    Yeah I did tell the manager at the service center about the chain response. I was kind of clueless as well since I didn't think there were any chains in there but I am no expert. Never will go there, ever.

    Well I finally had time over the weekend to put in the new Fan Clutch which GMC told me after brining it in there they were 99% positive that was the problem. Hundreds of dollars later and the same noise. I haven't check to see if the new clutch was bad since it takes a while to jimmy it out there. I am going to bring it in to someone I believe since I am still clueless.

    You are correct about the jet noise. When you are driving at about 35mph + and let off the gas the noise sounds like a jet engine powering down (just like in a plane when they are reaching their final approach) followed by the jake breaking noise (dada-dada-dada-dada-dada) which decreases with intensity as the engine idols down.

    Very Frustrating...
  6. Loggerhead Mike

    Loggerhead Mike Rockstar 100 Posts

    you took it to a gm dealer correct?

    sounds like a bad check valve in the AIR system, but a gm tech should of caught that. thats a tuff one without being able to look at it.

    take it to a different gm dealer and tell them you want their best man on it, youve wasted enough money having green horns fool with it
    Last edited: Jan 28, 2010
  7. carpem1

    carpem1 New Member

    Sorry for the delay, I was out of town on business for a bit. I did bring it in and have them replace the fan clutch. After $500 it didn't do anything. The dealer wasn't sure what the problem was. They wanted to look at it more for a lot more $$$. The guy did say he thought it was something with the AWD and 4WD, but when he moved the switch to move between them he didn't see a difference.

    So, on Saturday I was out doing some shopping and my SUV made the noise like it was click like it was changing from 4WD to 2WD without me switching it over. Only problem was I didn't switch it over, it more acted like it was stuck for about 2 weeks. Which would lead me to believe why the dealer didn't find it, because the vehicle didn't actually switch over at the dealership.

    This occurrence made the situation more relevant now. Now the jake breaking noise only happens if the AWD or 4WD is activated. In 2WD the sound goes away completely. Now I just have to bring it in AGAIN to see what part of the SUV is causing this problem.

    After my experiences with GMC dealers I am not sure if I will be able to buy another GMC. I have been loyal my hole life, but I have had to replace items that failed and I am up to about $5,000 in two years on repair bills. Amazing nothing started happening until 2 months after the warranty expired. Since then it has been something new every 3-4 months.
  8. tlperry68

    tlperry68 Epic Member 5+ Years 1000 Posts

    Well I'm not sure where you live but if you live in southern california I can point you to two dealeships where I personally know some of the guys there. They will trwat you right.
    I don't know if this is of any help or not but I have a jet like sound from my truck (I call it warp drive) when it is warm out and I'm towing a heavy load. It comes on when I accelerate from a stop or low speed. It is the fan so thats probably why you are getting fan clutch reports.

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