strange rattle

bradrhale · 01-01-2009, 12:31 PM

on my 99, i have a metalic rattle when the truck is under load. coming off a stop light will not make it but increasing speed up a hill or passing will start it. i had thought it was a heat shield but upon inspection, everything is nice and tight. pipes are tight. what i wonder about is the cat. when i hit the pipe next to it, it does rattle. thought it was the shield around it but it does not budge or move any. no SEL but am wondering if something can come loose in there to cause this rattle but not give a code.
i looked everywhere and shook near everything that i could get my hands on. even discovered that it may be getting time to replace the rubbers for the stablizer bar. (that will be on the back burner for a little while)

also, can someone tell me anything about the NP231d that i have. am not familiar with them.

silverhairdeere · 01-01-2009, 05:46 PM

i think that your cat is starting to come apart , so that when you gas on it there is more force to blow thestuf around on the inside . going throgh the same thing myself . no code yet because it not clogged up enough to siginal one yet . try this on the np231d .
http://www.jpmagazine.com/howto/5449/index.html

silver hair deere

bradrhale · 01-01-2009, 07:17 PM

thanks for the link.
the first o2 sensor bung is located in the actual cat. the second is located about 8 inches after the welded section, not flanged. might be time to invest in headers back to the muffler. muffler is aftermarket flowmaster.

gmctrucks · 01-01-2009, 07:18 PM

I too believe it's the cat it coming apart HOUSTON. My truck started making a little rattle before the fly wheel came apart and fell down the only part of the fly they stayed on the engine was the center section where it bolts to the engine.

silverhairdeere · 01-01-2009, 08:19 PM

your welcome , is houston your middle name

silver hair deere

bradrhale · 01-02-2009, 06:52 AM

my middle name is trouble.
if in fact it is the cat going out, i am kinda stuck at a crossroads. usually when something starts to go wrong, i will sell the vehicle and go buy something else. i have grown kinda fond of this truck but at the same time, something else sure does sound good.

silverhairdeere · 01-02-2009, 08:13 AM

i went through the same thing when i was younger , mine was women, relationships , and cars

silver hair deere

leolkfrm · 01-02-2009, 08:32 AM

As long as it burns out clean and the cel doesn't come on drive it! you sure it's not a spark knock?

bradrhale · 01-02-2009, 09:43 AM

really havent dug that far leo. it was doing this before i blew up that last set of plugs. never did change the cap and rotor because of its location. if i change them out, i think it would take away that extremely light stutter that it has at idle. it will not rattle at any particular speed and even at highway speeds it wont do it. just when i push the juice to her over the 2500 and 3000 mark. the harder i get on it, the worse she sounds. as i would love to forget about it, it makes me look bad. here is this great lookin truck setup the way it is with a rattle. i cant have that.

leolkfrm · 01-02-2009, 10:56 AM

easy way to check if it's a knock, octane booster or a tank of good premium fuel. if it goes away or gets better its a spark knock

01-01-2009, 12:31 PM	#1
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	strange rattle on my 99, i have a metalic rattle when the truck is under load. coming off a stop light will not make it but increasing speed up a hill or passing will start it. i had thought it was a heat shield but upon inspection, everything is nice and tight. pipes are tight. what i wonder about is the cat. when i hit the pipe next to it, it does rattle. thought it was the shield around it but it does not budge or move any. no SEL but am wondering if something can come loose in there to cause this rattle but not give a code. i looked everywhere and shook near everything that i could get my hands on. even discovered that it may be getting time to replace the rubbers for the stablizer bar. (that will be on the back burner for a little while) also, can someone tell me anything about the NP231d that i have. am not familiar with them.

01-01-2009, 05:46 PM	#2
silverhairdeere Senior Member Join Date: Feb 2008 Location: land between the lakes tn Posts: 1,118	i think that your cat is starting to come apart , so that when you gas on it there is more force to blow thestuf around on the inside . going throgh the same thing myself . no code yet because it not clogged up enough to siginal one yet . try this on the np231d . http://www.jpmagazine.com/howto/5449/index.html silver hair deere Last edited by silverhairdeere; 01-01-2009 at 06:03 PM.

01-02-2009, 08:32 AM	#8
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,225	As long as it burns out clean and the cel doesn't come on drive it! you sure it's not a spark knock? __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

01-02-2009, 10:56 AM	#10
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,225	easy way to check if it's a knock, octane booster or a tank of good premium fuel. if it goes away or gets better its a spark knock __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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01-01-2009, 07:17 PM	#3
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	thanks for the link. the first o2 sensor bung is located in the actual cat. the second is located about 8 inches after the welded section, not flanged. might be time to invest in headers back to the muffler. muffler is aftermarket flowmaster.

01-01-2009, 07:18 PM	#4
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 3,948	I too believe it's the cat it coming apart HOUSTON. My truck started making a little rattle before the fly wheel came apart and fell down the only part of the fly they stayed on the engine was the center section where it bolts to the engine.

01-01-2009, 08:19 PM	#5
silverhairdeere Senior Member Join Date: Feb 2008 Location: land between the lakes tn Posts: 1,118	your welcome , is houston your middle name silver hair deere

01-02-2009, 06:52 AM	#6
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	my middle name is trouble. if in fact it is the cat going out, i am kinda stuck at a crossroads. usually when something starts to go wrong, i will sell the vehicle and go buy something else. i have grown kinda fond of this truck but at the same time, something else sure does sound good.

01-02-2009, 08:13 AM	#7
silverhairdeere Senior Member Join Date: Feb 2008 Location: land between the lakes tn Posts: 1,118	i went through the same thing when i was younger , mine was women, relationships , and cars silver hair deere

01-02-2009, 09:43 AM	#9
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	really havent dug that far leo. it was doing this before i blew up that last set of plugs. never did change the cap and rotor because of its location. if i change them out, i think it would take away that extremely light stutter that it has at idle. it will not rattle at any particular speed and even at highway speeds it wont do it. just when i push the juice to her over the 2500 and 3000 mark. the harder i get on it, the worse she sounds. as i would love to forget about it, it makes me look bad. here is this great lookin truck setup the way it is with a rattle. i cant have that.

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