exhaust rattle? please help
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From: Livingston
exhaust rattle? please help
for some reason the exhaust on my 91 7.3 diesel 4x4 is making terrible noise. It was hardly noticable when the muffler was in place but I straight piped it and it is a loud rattle now. It sounds like a huge exhaust leak but like I said it got loud when my truck got straightpiped. could this be an exhaust leak? or do you think this is an engine problem? any one know of this before?
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From: Northeastern Pa - USA
On my 88 ( after straight piped ) it would make this noise against compression that sounded like a helicopter but would diminish around 2000 rpm or lower. I dont know if that is the sound you are hearing or not. It did nothing to hurt the operation or life of the engine. Just dont go winding it up to 3300 and let off, that might get some valves floating and banging against pistons. Hope this helps
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From: Livingston
I dont know exactly what Im talking about. Its is a rattle and I can only hear it at an idle. with the muffler on it is hardly noticable but whithout the muffler it is terrible. I really want to straight pipe this pickup but that rattle sounds terrible. you sit at a light and it rattles. I went to a good diesel mechanic and he opened the hood and revved it while listening to the engine (not the exhaust) and he said not to worry about it because if I had sucked a valve we could here it by the engine. Thats good news but I still gotta figure out how to stop that noise
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From: Northeastern Pa - USA
If it is a manual trans, it may be the flywheel (dual mass type) or if it is an auto, it may be the converter or the flex plate. I forgot about my 88 doing that also. I changed the converter and it still made the noise, so I suppose it was the flex plate and I wasnt going to pull the trans again just for the noise. Pop always said, it will show up if its bad enough.
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From: Monroe, WA
Good call Kitsap! I just checked his signature and sure enough, 5 spd! He probably needs a new flywheel, now to figure out why it's worse with the straight pipe.
Chris, have you crawled under the truck when it's rattling? Look under the bell housing, is the noise coming out of that tin inspection plate?
Chris, have you crawled under the truck when it's rattling? Look under the bell housing, is the noise coming out of that tin inspection plate?
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From: New York
my zf use to rattle like crazy sounded like a bearing going out. no dual mass flywheel on it. if ya gave it just a little tiny bit of throttle it quited rite up. i just turned the idle up slightly on my truck and now i only hear it occsiaonlly when i let the negine just idle in second gear up a hill or twoing somthing. soon as i put the hammer down quites rite up.
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From: Livingston
Thanks a lot for all the ideas. I honestly cant believe this could be a flywheel problem, Im not a mechanic, just a ranchhand but it is loader when straight piped and that makes no since to me this would have anything to do with the exhaust. Is their something Im missing? I just crawled under it and the Ticking is clearly heard from the end of the exhaust pipe. There is no Ticking under the bell housing inspection plate where the clutch is. Im at the end of my rope.
any Ideas?
any Ideas?
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From: Monroe, WA
Well, there goes the flywheel theory...
Does the engine miss when this is happening? I'm wondering if you have an exhaust valve going bad, chirping out the pipe. I wish I could hear it, I'd probably know what it was then.
Does the engine miss when this is happening? I'm wondering if you have an exhaust valve going bad, chirping out the pipe. I wish I could hear it, I'd probably know what it was then.
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From: Livingston
The engine never misses. this is getting very puzzleing
I know a guy who is a good diesel mechanic and he said it was not a valve.
he opened the hood and reved it while under the hood and he said he was lost. He told me not to worry about it, he didnt think it was a problem but im tired of it
I know a guy who is a good diesel mechanic and he said it was not a valve.
he opened the hood and reved it while under the hood and he said he was lost. He told me not to worry about it, he didnt think it was a problem but im tired of it
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From: Monroe, WA
Yeah, not much chance of convincing people it's a supercharger or something. 
I think the next thing I'd do is to take the exhaust off the manifolds and fire it up. Just long enough to see if the noise is coming out of the engine or being manufactured (somehow) in the pipes. There's my... what are we up to... 20 cents.
I think the next thing I'd do is to take the exhaust off the manifolds and fire it up. Just long enough to see if the noise is coming out of the engine or being manufactured (somehow) in the pipes. There's my... what are we up to... 20 cents.
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From: Livingston
Spectramac; This wont hurt the motor will it? Ill try it tommorow If it is in the engine I should surely be able to hear it with no pipes huh ok thanks Ill let you know how it goes.
ok thanks Ill let you know how it goes.