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Chevy Silverado and GMC Sierra Exhaust System Questions

pbug777pbug777 Member Posts: 4
I own a 2000 chev silverado 2500 with a 6.0 litre. I recently had dual exhaust installed on it (they sound sweet by the way). Before it was installed, i wanted them look at an exhaust leak i could hear near the engine compartment. Which i thought was the collector gasket. With out even looking the guy said "its probably the exhaust manifold bolts." Sure enough, looked under the hood and the front and the rear bolts were broke off on the drivers side. He said he's ran into that alot and that they break flush with the head so you have to remove the head because there's not enough clearance between the head and the firewall.
Has anyone else had this problem?
I've heard it happens on the 5.3 liters too.


  • marky3130marky3130 Member Posts: 3
    pbug777 I have the same problem. I also own a 2000 Chevy Silverado 2500 with the 6.0L and I had an exhaust leak that I could only pin to the drivers side manifold but I didn't know where. After reading your post I went and looked and sure enough I am missing the front two exhaust manifold bolts on the drivers side. Out of curiosity, did you get it fixed and how much did it cost?
  • pbug777pbug777 Member Posts: 4
    No, i haven't had it repaired yet. I've been quoted a minimum of $400 dollars by a chevy dealer because they want to take the heads off to take the bolts out and can't guarantee the removal of them. I have bolts broke on cylinder #1,2, and 7. Number 1 and 2 i was thinking of just using an easy out because you can get to them easily. Number 7 is the problem, there's not enough clearance to get anything in there because of the firewall. I'm waiting till it gets warmer out, live in minnesota. Call GM head quarters and make a complaint about it. If there's enough complaints they will make it a recall. I've heard in some states it's already a recall, not sure which ones or if its true. If you find out more info please keep me informed and I'll do the same.
  • marky3130marky3130 Member Posts: 3
    Now that the weather has warmed up I finally tackled the broken bolts. I got lucky when I removed the remaining 4 bolts as none of the heads broke off. Took awhile to get the bolts loose where the manifold connects to the head pipe but I finally muscled them off and got the manifold out. After removing the plug wires and some other things I could finally get at the bolts. Fortunately there was a 1/4 inch of the bolt sticking out of the block on both bolts. I got some vise grips on them and once I got them turning they came out without too much trouble. Took forever as I could only get about a 1/4 turn before I had to release the vice grips and reset them. I replaced all 6 bolts on the drivers side as I already had them out. Total cost: $15.50 for the bolts. (Gasket was still good) Total Time: 3 hours
  • klobearklobear Member Posts: 1
    I just had my drivers side replaced($1600.) This is the 2nd time. Dealer said other than a small cut in parts cost there was no recourse. The sad part is, the 1st time(3 yrs. ago) warranty covered the cost, and they replaced both manifolds, but put in the same type of bolts. Now the techs tell me the fix is a bolt with a larger head. I live in Canada and would like to hear from any one that has the same problem.
  • stacks125stacks125 Member Posts: 6
    I have a 1995 GMC Sierra 4x4 350 extended cab shortbed and I am putting it in my buddies barn to do a lot of work on it. One of the things is new exhaust. I don't really need to replace everything but I thought I just should since I'm putting on headers, one more cat for true duals and two new flowmaster mufflers and tips.(allready halfway there) I am pretty good at welding so I can do it all myself for it will be a lot cheaper. I bought flowtech headers(long) about a year ago and still have not put them on, so now would be a good time. I did not purchase a y-pipe to connect them so I thought I would just make it true dual exhaust.(kinda a all around handyman) Right now the exhaust goes from my two manifols into on catalitic converter and then back into duals with two mufflers(owner before me did that whole setup). The oxygen sensor is right in front of the catalitic converter. MY PROBLEM is that when i make it true duals there is only one oxygen sensor, so would anyone know how to hook up a second one, and where to hook it into, so the computer still reads both banks and doesn't make the truck run bad because it can't read one bank. Maybe all I have to do is splice it into the other one? don't know. thanks a lot for your help Derek
  • pawngodpawngod Member Posts: 4
    well i got my 08 denali sierra awd....curious what that muffler looking thing is at the passenger rear tire....has anyone removed it as a mod over replacing w/after market cat back? i also want to remove the front bumper license plate holder as i dont need it in okla. i cant see any bolts on it...anyone know how to remove it??
    would adding a volant cai void the warranty? not impress w/the 14,4 gal i been averaging...w/only 3 tanks of gas and around 1000 miles on it sofar....tranny seems funky..but hoping its still breakin in...thanks in advance
  • tigerpwrtigerpwr Member Posts: 1
    I have the same question as stacks about the O2 sensors. Any help on this would be great.
  • obyoneobyone Member Posts: 7,841
    would adding a volant cai void the warranty? No, but it would add to the noise in the cab while not improving much on anything.

    i also want to remove the front bumper license plate holder as i dont need it in okla. Isn't the plate holder molded as part of the bumper?

    tranny seems funky

    Yeah GM hasn't gotten the programming right on the 6 sp auto.

    curious what that muffler looking thing is at the passenger rear tire

    If it's smaller than the muffler it's probably a resonator and will be removed if installing a catback which again doesn't do much except increase incab noise.
  • obyoneobyone Member Posts: 7,841
    You can buy a fake O2 sensor online which will give a false reading to the computer at all times without affecting performance. This one fake O2 sensor should be enough so as not to be concerned with the other exhaust manifold.

    Course if you're concerned about passing emission testing well you can forget that.
  • cowboycadillaccowboycadillac Member Posts: 3
    I'm kinda curious as to how involved troubleshooting an "egr system failure" code on my truckis. As the truck is pushing 14 years old i figure this kinda stuff happens but i dont wanna tear into it completely blind. If anyone has any tips or ideas as to what the most common causes are, Lemme Know! i just put a new O2 sensor in a month ago so thats not it. The damn check engine light comes on and goes off sporadically so i figured it was just the gas cap leaking but the clown at O'reilly's says this is the problem, whatever. Any Help would be appreciated.
  • stacks125stacks125 Member Posts: 6
    thanks for the tip, I'll have to look into that, Stacks
  • pbug777pbug777 Member Posts: 4
    check for leaks aroung your intake manifold, i have the same problem with the check engine light going on and off and a mechanic told me to check for that. I haven't had time to check yet. He said just spray water with a little bit of soap aroung the intake while its running.
  • alaska49alaska49 Member Posts: 1
    i have a 2003 sierra 1500 and i was wanting to do something with my exhaust, possibly 3 inch straight pipes. I live in saskatoon, and i was wondering where the best place would be to go to do something like that! I just cant stand not being able to hear my truck roar when i drive, its just too quiet.
  • obyoneobyone Member Posts: 7,841
    3" straight pipes will get you a lot of sound but a loss in performance also due to lack of restriction. Any muffler shop should be able to do this for you and throw on a couple of glass packs. There are other alternatives but they are expensive.
  • rsorlingrsorling Member Posts: 2
  • balichbalich Member Posts: 62
    This is a weird one .. hopefully someone can give me suggestions:

    Just recently (starting last month) .. when I park truck in garage (its shut off) ... after 10 minutes... I would hear a BANG noise - consistantly each evening .. I was not sure what it was .. so I stayed under truck each night .. and sure enough - after approx 10 minutes .. I would hear a single BANG - pretty loud.

    After monitoring this .. I notice the bang is coming from muffler.

    So I hear a single loud BANG after my truck(turned off) sits for 10 minutes.

    Any ideas ? The truck runs and sounds fine .. just a BANG after truck sits for 10 minutes .. this is consistant behavior.

    I am hoping someone has seen this before ?

    Truck is almost 6 years old - 25K miles - original exhaust.

  • obyoneobyone Member Posts: 7,841
    Following what you stated that the sound is coming from the muffler, the only thing that's in the muffler is metal and fiberglass. So assuming that the metal is cooling the sound is from the metal contracting while cooling. It could be that one of the baffles is cracked causing more noise than normal or making it more noticeable.
  • Brandon4387Brandon4387 Member Posts: 2
    Hey I'm new to this. I've got a 2007 Chevrolet Silverado with the aluminum block 5.3 litre engine.
    I bought it new and had a flowmaster dual exhaust system installed on it when i first got it. Every since I had it installed, the engine kinda stutters, i guess you could say, but it is more noticeable when you around 50 mph or so, and when you get over 60 mph the engine will clear up and run smooth.
    Has anyone else had this problem? I would appreciate some help. Thanks!
  • obyoneobyone Member Posts: 7,841
    Not to dump on your choice of exhaust systems but Flowmasters has to be one of the worst systems perhaps next to Gibson. They will break down in 4-5 years, cause in cab resonance, loss of lowend torque and rattle. The engine stuttering might be caused by an exhaust leak from a bad install. Then again, was this particular flowmaster system designed specifically for the Silverado or was it installed by a local muffler shop using flowmaster mufflers and homemade pipes?

    A Borla or Corsa system designed for the Silverado would deliver a little better performance.
  • Brandon4387Brandon4387 Member Posts: 2
    I forgot to mention that it is a silverado classic, but anyways, I think that flowmaster has the best sounding muffler tone of any exhaust system, and also yes it was installed by a local muffler shop and I'm not sure if it was specifically for my truck or not. It's almost like you're just feathering the throttle untill you get to about 60 mph. You can only tell it when it is in overdrive and the transmission sometimes shifts from 3rd gear straight to overdrive and skips 4th gear. I will check underneath to see if I can find an exhaust leak but I cant hear it from outside the vehicle. Thanks for your input
  • obyoneobyone Member Posts: 7,841
    While under there checking for the leak make sure you check the connections BEFORE the muffler. Also check the O2 sensors, sometimes these exhaust guys while banging around under the truck bang one too many things.
  • hack5666hack5666 Member Posts: 2
    I have a 2008 GMC Duramax 6.6 LLM and I want to do something with my exhaust and was wondering what would happen if I were to cut out my cat and straight pipe it from the turbo back. I have recieved several different answers when I ask what it will do to my truck. I am not worried about the warranty, unless it will cause damage, anyone that can give me a straight answer will be greatly appreciated, also if it wont hurt my truck, how much louder will it make it.
  • hack5666hack5666 Member Posts: 2
  • manombomanombo Member Posts: 1
    I have the same problem with my 2002 Silverado 1500. I developed an exhaust leak on the driver side and when I looked to check it out, I thought the back two bolts had fallen out. I went to the dealer to get replacements, but the were out of stock (which I thought was odd). When the special order came in they were different. The new ones had a larger head. Now the bad part... When I attempted to install the new bolts I found the old bolts had actually broken off in the head. Before I tear my cylinder head off the truck, does anyone know if there has been a recall on these?
  • akjbmwakjbmw Member Posts: 231
    Do some checking on what your local requirements for smog checks are/will be.
    I understand that there will be a smog check required here for my '07.5 LMM starting next year.
    The previous owner went to an aftermarket exhaust from the DPF back that wont affect the test. There are folks at the dieselplace.com site who have done and reported on multiple combinations of exhaust mods for the various Duramax generations.
    I am inclined to believe that it is an aesthetic thing 'cause I REALLY don't see ever reaching the break-even point on the ROI. I think it would be a LOT more miles than I will put on it. Even considering that I will be pulling a trailer most of them.
    Yes, I like the exhaust sound but would not consider spending for the conversion. Also, I have no idea what the original exhaust sounded like.
  • olemissrebsolemissrebs Member Posts: 1
    i have a 2002 chevy silverado. i already have dual exhausts on it. i have a muffler and a cat. im taking the muffler off and putting in a y pie. will doing that mess anything up with the truck. or will every thing stay the same but it will just be louder?
  • obyoneobyone Member Posts: 7,841
    When you state dual exhausts I'm assuming true duals from the exhaust manifold to the tailpipe. Installing a Y pipe you're converting the dual setup to a dual in/ single out exhaust? If this is the case, it probably won't be louder and with more restriction you'll probably get better lowend.
  • nolonger8nolonger8 Member Posts: 1
    I have a 2004 2500hd with 30000 miles. i have been fighting with gm for 2 years on this issue right after the 3 year warranty my driver side went, they did under good will, 2 months later my passanger side went they would not honor it. now a year later my driver side is bad again. Im getting now where< i dont like spending 1000 every 8 months or so on this, is ther a recall or is this just super poor product?
  • stunner293stunner293 Member Posts: 2
    iv got a 01 sierra 4.8 293 it has a single in dual out flowmaster 40 series and turn downs sounds great at low rpms but not past 2 grand. wonderin what would really make it roar at low and higher rpms?? also thinkn bout runnin a y-pipe then 2 single-in single-out flowmaster super 40 series?? let me know what u think and or any other systems u think or know sounds jus badass. thanks
  • obyoneobyone Member Posts: 7,841
    Cheapest would be to cut out the flowmaster and install a glass pack. Better yet skip the glass pack and weld a straight pipe in it's place. ;)
  • stacks125stacks125 Member Posts: 6
    i have a 95 gmc with the 350 tbi motor, i have flowtech headers and then 2.5" pipe running all the way back with a h-pipe from flowmaster right after the headers and no cats with two super 44series and then it cuts out right after the rear axle to keep it hidden with no tips, its got a great low, high horsepower sound with no rasping at all and everyone that hears it seams to like it and yes it still is loud but sounds good
  • kommeatkommeat Member Posts: 1
    Okay now I'm confused I've done dual exhausts on several vehicles and this one has stumped me. I'm Running 2.5 inch Duals from the Manifolds back. I'm Using Holly RedHot glasspacks on each side. With the vehicle in park reved up to even 4k the trusk has a nice purr not overly loud but just enough for the good dual sound. I put this thing on the road yesterday and MASHED the pedal to see what it would do. The minute the engine broke 2500 RPM this thing sounded like it had NO exhaust whatsoever. I pulled the glass packs to see if i had one in backwards cause they weren't marked for easy installation and i've taken them off two or three times while tweaking the pips to make sure they fit perfect. The glass packs were installed properly. I Also noticed i have a MEAN tick in the donut gasket on the passenger side so i pulled the pipe at the manifold and checked the donut ring. it looks fine and seals properly to the naked eye. Both rings got replaced when i put the duals on so i know there is no wear in them and this was the trucks first run. ANYONE got any ideas. I'm stuck as to why this things gets so loud at higher rpms but only under load. Oxygen sensor reading show normal at idle and it never kicks the S.E.S. light on so i dont think its bad burn. The passenger side has a little funky smell to it when first running but i think that might be cause the truck hasn't run in like 7 months and it was running lean a little rich while the computer was resetting. (battery has been out for the whole 7 months so computer had to reset)
  • shortboxfevershortboxfever Member Posts: 1
    hi i have a 2007 shortbox reg cab 2wd sierra(new body style) and ive intstalled tru duals with glass packs. sounds like the garbage i thru out last night. i was wondering does anyone know how to bypass the o2sensor and co sensors on either side of the cat. any info would be great thanks!!
  • keshabell305keshabell305 Member Posts: 1
    I just purchased a 1996 chevy tahoe 4WD, and we have changed the oil. it still had lots of exhaust smoke, but less than it did before the oil change. After maybe 20 minutes of driving,there is always white smoke and fumes. please let me know what is going on. :(
  • obyoneobyone Member Posts: 7,841
    edited April 2010
    White smoke is not good. Usually indicates a blown head gasket. The reason there is less of it after the oil change is because the new oil has less coolant mixed in with it.
  • glock75glock75 Member Posts: 1
    Kommeat, I have a gmc 3500 with a pass side leak that sounds like the doghnut did u fix urs and if so what was it mines also a tick. Thanx
  • aljamea3aljamea3 Member Posts: 1
    I have a 2004 gmc sierra 3500 with a 6.0 gasoline engine and just got a new long tube headers for it but don&#146;t know how to do the exhaust design and I have a borla muffler so dose any one have any useful ideas I mean should I make it with one in put and two out puts or the opposite or two out and two in and what pipe should I use Y pipe, X pipe or H pipe what is the best to get the most power and an aggressive truck sound.

    :confuse: :confuse: :confuse: :confuse:
  • durmax07durmax07 Member Posts: 1
    We just traded a 2002 Chevy Silverado 1500 HD with the 6.0L and 4:10 rear gears. Back in March 10 I heard the exhaust leak and thought it was the exhaust gaskets, however it was the manifold bolts. Only 2 bolt on each side were holding the manifold on. I got lucky and the mechanic was able to get them out without pulling the heads. Cost $1200.00
  • obyoneobyone Member Posts: 7,841
    $1200 to tighten the exhaust manifold bolts?
  • davejrdavejr Member Posts: 1
    I took my truck into the dealer yesterday to have the exhaust manifold replaced. This is after I had been complaining for months about a leak and the noise it was making. And by the way, at 50,000 miles the dealer replaced the cam and lifters becuase they had worn to the point that the engine was making strange noises. This will be my last American made vehicle. Should have stayed with my Nissans, Toyotas and Hondas......Out 360,000 miles on my last Nissan before the timing change stretched and began to run rough. In 70,000 miles this GMC has spent more time in and out of dealerships than it has on the road.
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    I am sorry that your Sierra has not been a satisfactory vehicle for you. Is it still at the dealership for repair, or have you gotten it back? I look forward to an update on how it runs after the dealer visit, and if we can be of any assistance, please let us know in an email with more information on your situation.

    GM Customer Service
  • brianm60556brianm60556 Member Posts: 1
    I have the same issue on my 2009 Chevrolet 2500HD. This truck has never been abused or used for towing yet. I went to the dealership yesterday and they told me this is not covered under my warranty. I came home and looked at what is covered, and it says "manifolds" in the items listed. I'm going to follow up AGAIN with the dealership and try to get them to pay to fix something that was poorly engineered. Perhaps Sarah can suggest who at GM I can contact to get this resolved???? I payed enough for the truck that some simple exhaust bolts should be fixed.
  • gmcustsvcsarahgmcustsvcsarah Member Posts: 1,964
    Good evening,
    We'd be happy to look into this further and move towards a resolution. Please email us at socialmedia@gm.com with the following information so we can get a case started: your name and Edmunds username, phone and address, the last 8 digits of your VIN and current mileage, and the name of your involved dealership.

    All the best -
    Sarah, GM Customer Service
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