# Strange Rattling Sound from Engine Bay



## PhxJosh (Jun 27, 2009)

Sounds like something is loose, not sure exactly. It's coming from the passenger side, sounds like it might be one of the pulleys? 

Would it help if I recorded the sound, or even a video of the engine bay running? 

I hear it right when I start the car, and while driving, seems to get louder as I accelerate.


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## Jdoggsc (Dec 25, 2007)

can you not hear it when your car is on and idling? If so, i would suggest you turn it on, pop the hood, and try to follow the noise. If you want to simulate accelerating, just tug on the spring-loaded throttle cable hanger on the throttle body. could just be a pulley issue. hope it is. if it's a timing chain or camshaft issue, i'd hate to be you.


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## PhxJosh (Jun 27, 2009)

Jdoggsc said:


> can you not hear it when your car is on and idling? If so, i would suggest you turn it on, pop the hood, and try to follow the noise. If you want to simulate accelerating, just tug on the spring-loaded throttle cable hanger on the throttle body. could just be a pulley issue. hope it is. if it's a timing chain or camshaft issue, i'd hate to be you.


I can hear it while sitting in the car, it's most noticeable when idling in park, I think driving sort of muffles the noise. 

I traced the noise to somewhere near the belt pulleys, they all look secure and don't look like they're loose or anything. 

I am going to take a video of the noise, that might help?

Thanks for the help man, you're the only one who has responded to my threads haha!


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## nova73guy (Mar 30, 2004)

I've heard a few guys talking about the bottom bolt on the alternator coming loose. I checked my car when I got a rattle and the bottom bolt was gone! Check all your mounting bolts and make sure everything's tight. If it's a fairly high-frequency rattle it may be coming from the timing chain/guides.

One real easy way to tell is take a LONG (18" or more) screwdriver and carefully place it on the alternator, steering pump, water pump, etc. and hold the other end to your ear. That will help narrow down the source. Hope this helps.


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## PTXer (Aug 31, 2006)

A failing water pump will start to "rattle" and get progresively worse untill it lets go altogether. Mine lasted almost 3000 miles of city driving until it finally went. Again it started as a rattling or almost like a grinding mainly audible at idle and when cold. I confirmed it by taking the belt off and starting it - no noise. It was kind of a pain to get to on my 97. Changed the thermostat while it was all apart too.


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## PhxJosh (Jun 27, 2009)

PTXer said:


> A failing water pump will start to "rattle" and get progresively worse untill it lets go altogether. Mine lasted almost 3000 miles of city driving until it finally went. Again it started as a rattling or almost like a grinding mainly audible at idle and when cold. I confirmed it by taking the belt off and starting it - no noise. It was kind of a pain to get to on my 97. Changed the thermostat while it was all apart too.


That's funny because I was told this morning my water pump is bad. How hard was the replacement? I don't even know where the water pump is located.


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## PTXer (Aug 31, 2006)

Its on the "front" of the motor on the front cover (at least on my 97). Take the passenger wheel off, some of the wheel well splash guards to get the belt off and you can almost see it. I took the motor mount loose so I could jack up the motor to better get my hands in around all the AC stuff. I think its like 5 - 10mm bolts. Thermostat and housing is right there too (3 bolts). Used Ultra Grey RTV on the thermostat, 518 Flange sealant on the pump. Replaced my belts, upper/lower radiator hoses since they were original. Use Ultra Grey to seal the hose ends too. It was really a pain to get everything in and out of the cramped area, but if you have the time (4-5 hours) its worth saving the money. If only I hadn't put it off utill it totally went, could have saved the tow too.


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## IanH (Feb 11, 2003)

PhxJosh said:


> That's funny because I was told this morning my water pump is bad. How hard was the replacement? I don't even know where the water pump is located.


How many miles ??

if this isn't the water pump I suspect the upper timing chain.

Check as suggested above with a stethoscope of some kind.


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## PTXer (Aug 31, 2006)

As it is a little difficult to get to when running, you could try taking the belt off too and starting it up (briefly). If the noise is very apparent, and very absent with the belt off, that's probably it. Mine went at 125K


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## azkicker0027 (May 31, 2002)

if it sounds like some rattle/clattering at idle near the passenger side of the engine valve cover, it COULD be your upper timing chain tensioner. i recently replaced mine and it got rid of odd noises from my engine compartment when at idle.


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## nissannick1 (Feb 22, 2008)

Upper timing chain tensioner and water pump are a lot easier to replace with the mount out of the way and the engine jacked up a little. It sounds like tensioner to me though.


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## CASTLK (Feb 17, 2010)

Check the heat shield on the catalytic converter, the weld breaks on them and they rattle.


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## PhxJosh (Jun 27, 2009)

I think my heat shield is rattling, what is the best way to fix it? Do I need to just re-weld it back on?


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## Wax (Jun 9, 2017)

*Rattling noise*

Hi, i read all the conversation and i think this is helpful for us that know little about cars. I have this rattling noise also on my nissan pathfinder 2007. It happened when my car had overheat because my radiador was emptied. We changed the water pump because of leak. And when all are done when i start the car i heard a rattling sound on the car, and also its like the engine is about to stop when idle mode. What could be the problem of the car? It will be a big help for me all the inputs you will share... thank you


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## Sentra1999 (Nov 28, 2017)

if it comes from engine passenger side ,most likely is chain tensioner,you should smell it too,it burns the ceramic part then chain hits the metal part thtas why it rattles.


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## Dave77vb (Oct 6, 2020)

Hey I have the same issue it seems, rattling on the passenger side by the valve cover area. I changed the upper timing chain tensioner but it didnt fix it. Does anyone have an idea of what else it is???
Its also most noticeable when at idle.
Almost sounds like metal rattling against each other .


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## haissam.antonios (10 mo ago)

Hi Guys,

Need your help here. Hopefully someone can help. I own a 2018 Nissan Maxima SV done almost 50k. I have been heering a rattling noise only in the morning from the engine bay towards the passenger side ( Most probably when the engine is cold) it comes on bumpy roads and disappears after few minutes of driving. Its not there when iddle, just on low rpms and bumps seems like a loose plastic or something, but i couldnt figure out what is it yet. ITS JUST TOO ANNOYING AND LOUD.

Took it to the dealer twice, unfortunatly couldnt reproduce the sound as it only comes in during the morning and for few minutes, and unlickily the road to my house is interlock where the sound appears.

I have checked and sound proofed every plastic peice in the engine bay that i have seen and believed that might make a noice. The coolant tank where it meets the body, the engine cover top left where it also has contact with the body.
I have checked the heat sheilds, all look solid and in place.
I tied up all lights wirring assuming might be hitting on something.

Please let me know if anyone had expirienced a similar problem. Thanks.

I have added a recording of the noise if that helps.



https://maxima.org/forums/attachments/6th-generation-maxima-2004-2008/59040d1648624353-rattling-noise-untitled.avi


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## IanH (Feb 11, 2003)

so its only when cold.
when you start up in the morning its quiet until you get on bumpy road ? it does not do this when you rev up cold before driving ?
since it goes with engine revs I would automatically suspect bearings loose bolts alternator etc but if its internal engine it should not go away unless its oil starvation.
try the same drive when the engine is hot.
If this was one of my crap cars from 50's and 60's in england that recording would have me pulling the pan to replace the rod bearings before the crank gets damaged.

What happens if you up the oil viscosity full synthetic from 0 - 20W to 10-30W ? try maybe try it and change back immediately.

Since this is DD engine try higher octane fuel or an additive.

hopefully someone who has had this will respond.

Please read below for better answer !


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## VStar650CL (Nov 12, 2020)

Sounds like a bad overrunning clutch in the alternator pulley. Get a screwdriver long enough to reach the top of the alternator housing and use it as a stethoscope with the handle into your ear. If you hear the noise louder there than other places on the engine then it's time for an alternator.


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## haissam.antonios (10 mo ago)

IanH said:


> so its only when cold.
> when you start up in the morning its quiet until you get on bumpy road ? it does not do this when you rev up cold before driving ?
> since it goes with engine revs I would automatically suspect bearings loose bolts alternator etc but if its internal engine it should not go away unless its oil starvation.
> try the same drive when the engine is hot.
> ...


Hello, Nothing on startup, quiet and lovely even with engine revs. It only happens over bumpy roads and dissapear in few minutes when the engine gets warmer. Also, if i warm up the engine for few minutes before i drive i dont get the noise at all. The vehicle is still under warranty, but unfortunatly by the time it reaches to the service center the noise is gone and when i leave it over they just claim that they dont hear it in the morning. Its annoying and driving me crazy. Would a broken engine mount or strut mount make such a noise? Maybe when the grease heats up it dissapears?


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## haissam.antonios (10 mo ago)

VStar650CL said:


> Sounds like a bad overrunning clutch in the alternator pulley. Get a screwdriver long enough to reach the top of the alternator housing and use it as a stethoscope with the handle into your ear. If you hear the noise louder there than other places on the engine then it's time for an alternator.


Hello, wouldnt that also be noise when engine is on and idle? Please correct me if im wrong. But i do hear any noises till the car goes over a bumpy road.


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## haissam.antonios (10 mo ago)

haissam.antonios said:


> lease correct me if im wrong





haissam.antonios said:


> Hello, wouldnt that also be noisy when engine is on and idle? Please correct me if im wrong. But i do not hear any noises till the car goes over a bumpy road.


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## VStar650CL (Nov 12, 2020)

Bring the dealership the audio, or even better a vid so they can see RPM and temp. Dealerships' hands are tied when they can't "reproduce" your issue, but a clear vid will untie them. They'll probably want the car overnight to get it to make the noise.


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## rogoman (Dec 16, 2004)

haissam.antonios said:


> Hello, Nothing on startup, quiet and lovely even with engine revs. It only happens over bumpy roads and dissapear in few minutes when the engine gets warmer. Also, if i warm up the engine for few minutes before i drive i dont get the noise at all. The vehicle is still under warranty, but unfortunatly by the time it reaches to the service center the noise is gone and when i leave it over they just claim that they dont hear it in the morning. Its annoying and driving me crazy. Would a broken engine mount or strut mount make such a noise? Maybe when the grease heats up it dissapears?


You'll have to jack the car up; place jack stands for safety. Inspect all the exhaust pipe shields by taping them with a small hammer to detect looseness.


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## domnickjerron (6 mo ago)

PhxJosh said:


> Sounds like something is loose, not sure exactly. It's coming from the passenger side, sounds like it might be one of the pulleys?
> Showbox jiofi.local.html tplinklogin​Would it help if I recorded the sound, or even a video of the engine bay running?
> 
> I hear it right when I start the car, and while driving, seems to get louder as I accelerate.


it COULD be your upper timing chain tensioner


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