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Popping/Puffing Noise from Exhaust of K1500
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philip.camp
New User
Oct 4, 2011, 4:17 PM
Post #1 of 8
(6472 views)
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Popping/Puffing Noise from Exhaust of K1500
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Hey guys. I’m hoping you guys could help me out. I also hope I can give you enough information to help you guys make an educated guess. I have a 1995 Chevy K1500 with a 350 5.7. It has 200K+ on the body, but probably not more than 50K on a newer engine. However, I’ve owned this truck since I was 20 (young and stupid), and haven’t always taken care of it like I should, hence the engine change. For the last 8 years the truck has pretty much been parked with occasional driving that resulted from my motivation, at times, to fix the truck.
Situation:
My truck will crank up like a champ. It will idle like a champ. It does have the low toned knock for the first two couple seconds until the oil pressure gets up, which I've heard is common for GM trucks. However, after I’ve driven it down the road I noticed that when I decelerate at a stop sign or stop light I have a puffing noise coming from my right tail pipe (I have straight pipes). This noise sounds almost like you are relieving air pressure from an air line. I wouldn’t consider it a backfire only because I think of backfiring as a gunshot type noise. I feel like I should have bubbles shooting out from underneath my car. LOL! At this point I have no check-engine-light on, nor do I have any stored codes on the computer.
Maintenance Performed:
-Replaced Starter/Battery Cable because old wire melted to exhaust manifold
-Changed plugs / wires at least two times
-Changed EGR valve
-Temp repaired Left exhaust manifold cracks (unknown if Right side is cracked due to shroud being installed)
-Changed fuel filter
-Oil shows amber color with no signs of contamination
-Changed Distributor Cap/Rotor button
-Timing is Good (Checked with a light)
-Changed MAP Sensor
-Changed Idle Air Control Valve
At this point I’m scratching my head. I'm tired of throwing money at parts that MAY be bad and really want this truck fixed. Hopefully you guys can help me out…
Respectfully,
Phil
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 4, 2011, 8:09 PM
Post #2 of 8
(6439 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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Does it sound like this?
http://www.youtube.com/watch?v=XrsK2HtEXO0
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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philip.camp
New User
Oct 5, 2011, 11:54 AM
Post #3 of 8
(6426 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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No, sir. I will trying an upload a video later tonight. But I did check the compression on the right bank. The highest readin was 150 PSI, but cylunder @6 read 140, which is still within limits. Cylinder 6 and 8 both had a a little oil on the spark plugs too. Not sure if thats a bad thing or not.
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 11, 2011, 5:00 AM
Post #5 of 8
(6388 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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Have you determined with cylinders are missing on the right bank?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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philip.camp
New User
Oct 11, 2011, 8:14 AM
Post #6 of 8
(6380 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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How do I do that?
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 11, 2011, 5:59 PM
Post #7 of 8
(6370 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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While the engine is missing, you need to disable each cylinder one at a time. To do this on your set up, you need to disable spark or divert it to ground, so it doesn't go through the spark plug. The cylinder that doesn't make a difference in the rpm or change the sound of the engine is a dead cylinder.
Now, the tricky part. You really don't want to pull wires off while the engine is running because (1) you usually get shocked and (2) you can overload the coil. I usually take a 12 volt test light grounded with a dulled tip and slide it in between the boot and the wire at the distributor. Don't pierce the boot or wire. The voltage is going to go through the lamp instead of the plug.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Oct 11, 2011, 6:00 PM)
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Old 396
User
Oct 12, 2011, 3:44 PM
Post #8 of 8
(6349 views)
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Re: Popping/Puffing Noise from Exhaust of K1500
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Just for the sake of curiosity, when you get a chance can you post the results of a wet and dry compression test? To really create an impact post the results of a cylinder leak down test along with the results of the wet dry compression test.
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