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What is rattling?


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I have had this rattling sound coming from the upper area of the engine for a couple years. It seems to happen when the vehicle is cold and goes away once warmed up. It is a metallic sound like a jingle. It sounds as if its inside the intake manifold. Is there a valve of some sort in the intake that changes position when warmed up that could be causing that metallic jingle when the vehicle is cold?

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Nope, it is very metallic like a jingle. It increases in frequency and speed as I rev the engine but will disappear once the engine is warmed up. If I had to guess I would say some sort of valve inside the intake? It there something that prevents air flow when cold possibly that can get loose?

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Nope, it is very metallic like a jingle. It increases in frequency and speed as I rev the engine but will disappear once the engine is warmed up. If I had to guess I would say some sort of valve inside the intake? It there something that prevents air flow when cold possibly that can get loose?

hmm.. would it be possible to record the sound?

unless its something loose on the IAC (idle air control) which does change position as it warms up. (as far as i know?, i could be wrong.. but a recording would help)

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THERMOSTATIC AIR CLEANER....

 

Sounds like your car is pre-warming, their will be a flexible metallic tube going from the exhaust manifold heat shield to the air intake or air cleaner, where this hose attaches to the intake (underside) their will be a small round metal valve on top of the intake (coppery color) with a small black vacuum hose coming from it. when the car is cold and you turn it on the vacuum will activate this valve to open allowing warm air to be drawn via the flexible metallic tube from the exhaust heat shield (pre-warming) when the car is up to temperature the valve will close allowing fresh cool air into the intake. The round metal valve on top is not the problem, it will most likely be the butterfly which changes air direction inside the air cleaner it is metal on metal hence the rattle, you can remove the plastic piping that connects to the intake or air cleaner turn the car on when it is cold and shine a torch inside to see if this valve is operating correctly and or is the source of rattling. i have the same sound. i do not see it as a problem as it will last 15 minutes max. try and avoid removing any vacuum related parts from your car as it will be detrimental to the performance.

 

i hope this helped you and maybe someone else.

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My guess would be lifter noise from the driver's side, but you seem to not think that is it. There isn't really too much moving around in the upper intake manifold (and nothing at all in the lower). What Psyco is talking about kinda sounds like the EGR valve to me and it wouldn't make a sound like this...

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that engine is disgustingly clean

oh so true... get that thing grimy and dirty! :rofl: If there was a "under hood" TOtM month, you would definatly get a nomination!

 

Seriously though I gotta agree with a lifter tick sound, one of my HB's had a tinny-heat shield sounding rattle when cold that was a lifter tick. Once it got enough lubrication up top, the tick be gone!

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You guys have me laughing! I try to keep my vehicles clean, thanks for the props!

 

So is there any moving parts inside the intake manifold? I know what a lifter sounds like and its not that, it sounds very metallic.

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You guys have me laughing! I try to keep my vehicles clean, thanks for the props!

 

So is there any moving parts inside the intake manifold? I know what a lifter sounds like and its not that, it sounds very metallic.

 

Since the lifters are made of metal, I guess some of us aren't sure why the sound being "metallic" rules them out, but I'll take your word for it that it is different. I guess the throttle plate is sorta "inside" the intake. There are also the AAC and air regulator valves at the rear driver's side... other than that... nothing is coming to mind.

Edited by sewebster
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You could try to pinpoint the sound more specifically by holding a length of say, 1'' doweling (an old broom handle would work), by say 12-15" long to the engine block areas, Put the other end to your ear....it works like a doctors stethascope. Please be aware of moving parts when you do this. The sound waves will travel up the dowel to your ear. This is kinda like the 2 tin cans and a length of string idea..... Worth a try?

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Can you put your hand on the distributor cap cover while its running and feel it? When the timing belt has stretched far enough, the belt can "slap" and transer the noise up the distributor. Has the belt been changed at all? A recording or video would help out a ton.

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Can you put your hand on the distributor cap cover while its running and feel it? When the timing belt has stretched far enough, the belt can "slap" and transer the noise up the distributor. Has the belt been changed at all? A recording or video would help out a ton.

 

Ya I did the timing belt about 10,000 miles ago and had the sound previous and post timing belt replacement. Ill try to record a video of it when I start it in the morning on Saturday. Lets hope we can hear it over the ticking exhaust manifolds ;-)

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ok... something just popped into my head. After doing my timing belt the last time, I had a rattling that turned out to be the belt tensioner that peeks up from behind your fan shroud in your picture. I had tightened the bolt to apply tension but never tightened the bolt to hold it in place. Just another place that's easy to check.

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I have the exact same noise !!! When driving it cold it sounds like engine noise that comes from the radio but it's not that. Sounds like it's coming from the passenger side dash board !!! It's driving me NUT!!!!!!!!!

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when cold, oil channels can clog or be dry or extra thick or whatev. after heated up the journals flow properly. oil change + trusted cleaner. mine does it too, but i dont care really.

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