A little help please from Truck guys

RubyCamaro · 11-28-2013, 08:13 PM

Daddy's girl has a problem! Some of you will recall I bought my dad's 2002 GMC Sierra 4WD extended cab truck. It now has 24,66X mi on it. We drove it today 37 mi to my in-law's house & it drove fine. Coming home it started making an intermittant sort of backfire sound. Not a loud, jump-out-of-your-skin like a gun was fired sound but a more subtile "Pa". It is idling fine, ran great, shifting great, nothing unusual in gauge readings, no dummy lights. Mike looked at everything & saw no fluids leaking & no visable problems. It seemed to happen more often as he backed off the gas after some accelleration & more often between 45 & 55 mph and got worse the closer to home we got. Anyone have any thoughts/ideas about what it could be?

derklug · 11-28-2013, 09:32 PM

Exhaust manifold gasket or a cracked manifold would be my guess.

RubyCamaro · 11-28-2013, 09:39 PM

That does not sound good. With just 24K mi on it is that likely? How would a manifold get cracked?

yotaman96 · 11-28-2013, 10:40 PM

Hard to say for sure. Could be something as simple as bad gas. Other things that come to mind are a vacuum leak, coil pack going out, or an issue with the plugs or wires. If it keeps acting up, the check engine light will probably come on and give an idea of where to start looking. I believe intake manifold leaks are common on these as well.

LimaCharlie · 11-28-2013, 10:52 PM

Something like this is very difficult to troubleshoot without hearing the sound and actually driving the truck. I'm the original owner of my 2004 Silverado 5.3 and I've never experienced a sound like you described. Since you don't have a check engine light, my guess is you have an exhaust leak somewhere. Derklug's suggestion above is a good idea. Check your exhaust manifolds (both at heads and collector). They might be cracked. It's possible you have a leak on your intermediate pipe around the O2 sensors too. These are all pretty simple fixes.

Truck Norris · 11-29-2013, 02:34 PM

It's not always about how little miles it has, remember its pushing 13 years old now. Back in 2001 wouldn't you consider a vehicle built in 1987 pretty old and due for replacement?

Sounds like a coil pack going out. I'd take it to a local repair shop and pay the 1/2 hour diagnosis fee (which they will re-imburse if they perform the labor to fix it) to see exactly what the problem vs throwing parts at it.

RubyCamaro · 11-29-2013, 03:53 PM

Yeah, I get that it is old, but it is also sentimental. It was my dad's truck & he is now in assisted living & of course can't drive, so I bought his beloved truck. There are still a ton of these trucks on the road around here (farm country) & stuff for them is pretty cheap. I know I won't get a disgnosis & "cure" so to speak on a thread here. I was just hoping to learn what some of the possibilities are.

Mike put some gas treatment in it this morning & drove it around a while just in case it was bad gas & that quick fix might take care of it. Then we took it out shopping just around town. It has not done it any more today. So I'm not sure if that was it or because it is warmer today or if it is just one of those things that is going to tend to come & go. But we decided to wait a bit & see how it does. Mike can always take it by the shop any day.

Thanks guys.

11-28-2013, 08:13 PM	#1
RubyCamaro Jan Drives: 2010 Camaro 1LT Red Jewel tintcoat Join Date: May 2010 Location: Springfield, TN Posts: 16,241 View My Garage	A little help please from Truck guys Daddy's girl has a problem! Some of you will recall I bought my dad's 2002 GMC Sierra 4WD extended cab truck. It now has 24,66X mi on it. We drove it today 37 mi to my in-law's house & it drove fine. Coming home it started making an intermittant sort of backfire sound. Not a loud, jump-out-of-your-skin like a gun was fired sound but a more subtile "Pa". It is idling fine, ran great, shifting great, nothing unusual in gauge readings, no dummy lights. Mike looked at everything & saw no fluids leaking & no visable problems. It seemed to happen more often as he backed off the gas after some accelleration & more often between 45 & 55 mph and got worse the closer to home we got. Anyone have any thoughts/ideas about what it could be? __________________ Last edited by RubyCamaro; 11-28-2013 at 08:45 PM.

11-28-2013, 09:32 PM	#2
derklug Drives: 12 Boss 302 Join Date: Sep 2009 Location: Grand Rapids, Mi Posts: 1,369	Exhaust manifold gasket or a cracked manifold would be my guess. __________________ The biggest mistakes in life come when you know exactly what you are doing.

11-28-2013, 09:39 PM	#3
RubyCamaro Jan Drives: 2010 Camaro 1LT Red Jewel tintcoat Join Date: May 2010 Location: Springfield, TN Posts: 16,241 View My Garage	That does not sound good. With just 24K mi on it is that likely? How would a manifold get cracked? __________________

11-28-2013, 10:40 PM	#4
yotaman96 Drives: 2017 Camaro SS1LE 2000 Trans Am WS6 Join Date: Jul 2008 Location: Portland, TN Posts: 2,952 View My Garage	Hard to say for sure. Could be something as simple as bad gas. Other things that come to mind are a vacuum leak, coil pack going out, or an issue with the plugs or wires. If it keeps acting up, the check engine light will probably come on and give an idea of where to start looking. I believe intake manifold leaks are common on these as well. __________________ 2017 Krypton Green SS 1LE Magnacharged 2000 Trans Am WS6 manual trans 2002 Trans Am 2015 Ram Crew Cab Cummins

11-28-2013, 10:52 PM	#5
LimaCharlie Drives: 2011 Camaro SS/RS - 2004 Silverado Join Date: Mar 2010 Location: Las Vegas, NV Posts: 2,989	Something like this is very difficult to troubleshoot without hearing the sound and actually driving the truck. I'm the original owner of my 2004 Silverado 5.3 and I've never experienced a sound like you described. Since you don't have a check engine light, my guess is you have an exhaust leak somewhere. Derklug's suggestion above is a good idea. Check your exhaust manifolds (both at heads and collector). They might be cracked. It's possible you have a leak on your intermediate pipe around the O2 sensors too. These are all pretty simple fixes. __________________ 2011 Summit White Camaro 1SS/RS -6.2 LS3, TR6060, 3.45, G80 2004 Black Silverado 1500 2WD Regular Cab, Short Bed -5.3 LM7, 4L60E, 3.42, G80 2014 White Caprice PPV -6.0 L77, 6L80E, 2.92, G80

11-29-2013, 02:34 PM	#6
Truck Norris Thread Mover Drives: a Monte Carlo Join Date: Apr 2011 Location: Sierra Nevada Posts: 490	It's not always about how little miles it has, remember its pushing 13 years old now. Back in 2001 wouldn't you consider a vehicle built in 1987 pretty old and due for replacement? Sounds like a coil pack going out. I'd take it to a local repair shop and pay the 1/2 hour diagnosis fee (which they will re-imburse if they perform the labor to fix it) to see exactly what the problem vs throwing parts at it. __________________ In the market for something fast

11-29-2013, 03:53 PM	#7
RubyCamaro Jan Drives: 2010 Camaro 1LT Red Jewel tintcoat Join Date: May 2010 Location: Springfield, TN Posts: 16,241 View My Garage	Yeah, I get that it is old, but it is also sentimental. It was my dad's truck & he is now in assisted living & of course can't drive, so I bought his beloved truck. There are still a ton of these trucks on the road around here (farm country) & stuff for them is pretty cheap. I know I won't get a disgnosis & "cure" so to speak on a thread here. I was just hoping to learn what some of the possibilities are. Mike put some gas treatment in it this morning & drove it around a while just in case it was bad gas & that quick fix might take care of it. Then we took it out shopping just around town. It has not done it any more today. So I'm not sure if that was it or because it is warmer today or if it is just one of those things that is going to tend to come & go. But we decided to wait a bit & see how it does. Mike can always take it by the shop any day. Thanks guys. __________________