Odd rattling/clicking sound...

[giant_mtb]

So...I have the '96 Monte Carlo with the 3.4L V6.  Around 2500 (both above and below it) it makes a weird rattling or clicking sound.  It's difficult to describe.  It doesn't make the sound below ~2250 nor does it make the noise above 3000.  When I got my oil changed a week or so ago, the guy said that my serpentine belt needed to be changed.  Is it possible that because the belt needs replacing, it's causing this noise?  Maybe the valve timing is off because of it? 

I don't really know...it's just a very very annoying noise...any other ideas?

Edit:  I'm talking about RPM's here...I realize I didn't say "2500 RPMs", I just said 2500...anyways...

[280Z Turbo]

Were 3.4L's timing chain motors?

[93JC]

So...I have the '96 Monte Carlo with the 3.4L V6. Around 2500 (both above and below it) it makes a weird rattling or clicking sound. It's difficult to describe. It doesn't make the sound below ~2250 nor does it make the noise above 3000. When I got my oil changed a week or so ago, the guy said that my serpentine belt needed to be changed. Is it possible that because the belt needs replacing, it's causing this noise? Maybe the valve timing is off because of it?

I don't really know...it's just a very very annoying noise...any other ideas?

Edit: I'm talking about RPM's here...I realize I didn't say "2500 RPMs", I just said 2500...anyways...

Well, first of all an old serpentine belt won't throw off your valve timing. Serpentine belts run the accessories (alternator, power steering pump, air conditioning compressor, etc.) Timing belts are completely different, and are toothed so that timing doesn't go screwy. Even then, doesn't the DOHC 3400 V6 use timing chains? I don't know, but I was under that impression. (GM hasn't been big on belt-driven camshafts since the Vega engine fiasco 30+ years ago)

Rattling, eh? Hmm.... If it's something in, on or around your engine, it could be worn out tappets. At least, I'm pretty sure the DOHC 3400 uses bucket tappets or something to their effect.

I'd check the exhaust system, personally. My Cherokee has a broken exhaust hanger, and the exhaust pipe will rattle noticeably around 1000 rpm.

[giant_mtb]

Hmm...I like the idea of the exhaust...it's very possible.  Though I'm not sure how.  The car has seen only one winter (it was either not driven or stored during all its other winter seasons) so I dunno how it would rust out...but who knows!

You lost me at "tappets"...


Also, me and my brother figured it could possibly be a CV boot joint that's like...broken/loose/whatever...but we know nothing. haha

[93JC]

Hmm...I like the idea of the exhaust...it's very possible.? Though I'm not sure how.? The car has seen only one winter (it was either not driven or stored during all its other winter seasons) so I dunno how it would rust out...but who knows!

Most hangers use rubber at some point, and can easily wear out.

You lost me at "tappets"...

Blue things in the picture. They're usually hydraulic, and eventually they wear out, and when they do you can usually hear a clicking or rattling sound.

Also, me and my brother figured it could possibly be a CV boot joint that's like...broken/loose/whatever...but we know nothing. haha

Hmmm... CV joints do tend to make a clicking sound when they wear out....


But the sound wouldn't be dependent on engine speed. That wouldn't make sense.

[MX793]

I'd check the exhaust first.  Loose heat shields or broken/rotted hangers will cause RPM dependant noises (due to resonance).  I had a heat shield on my exhaust come loose and it would make an awful sound whenever the motor was at certain RPMs (1800 and again at around 2800 rpm).

[AutobahnSHO]

I'd check the exhaust first.? Loose heat shields or broken/rotted hangers will cause RPM dependant noises (due to resonance).? I had a heat shield on my exhaust come loose and it would make an awful sound whenever the motor was at certain RPMs (1800 and again at around 2800 rpm).

Same on my CRX.
CV Joints rattle like crazy but it's dependent on WHEEL speed, not engine speed.  Go around a corner under power and you'll hear them go nutz.

You can just poke around until you hear where it's coming from.

[280Z Turbo]

Well, first of all an old serpentine belt won't throw off your valve timing. Serpentine belts run the accessories (alternator, power steering pump, air conditioning compressor, etc.) Timing belts are completely different, and are toothed so that timing doesn't go screwy. Even then, doesn't the DOHC 3400 V6 use timing chains? I don't know, but I was under that impression. (GM hasn't been big on belt-driven camshafts since the Vega engine fiasco 30+ years ago)

Rattling, eh? Hmm.... If it's something in, on or around your engine, it could be worn out tappets. At least, I'm pretty sure the DOHC 3400 uses bucket tappets or something to their effect.

I'd check the exhaust system, personally. My Cherokee has a broken exhaust hanger, and the exhaust pipe will rattle noticeably around 1000 rpm.

DOHC 3.4L?!

I didn't believe it at first, but I looked it up and sure enough GM used a DOHC V6 in the Monte Carlo. Seems really strange.

[3.0L V6]

I'm assuming it's the LQ1:

Quoted from:
http://en.wikipedia.org/wiki/GM_60-Degree_V6_engine

The LQ1 (also called the Twin Dual Cam) was a special DOHC version of the 3.1 L LH0 V6. It was built from 1991 to 1997. 1991-1993 it used tuned multiport fuel injection, made 200-210 hp @ 5,200 rpm and 215 ft. lbs torque @ 4000 rpm. 1994-1997 it used sequential fuel injection (SFI) making 215 hp @ 5,200 rpm and 225 ft. lbs torque @ 4,000 rpm. It has four large valves per cylinder. The 3.4 L uses a cogged belt to drive the four overhead camshafts. The gearbox options for the LQ1 were a 4 speed Hydra-Matic electronic shifting transmission and a 5 speed Getrag 284 manual transmission, unique to the LQ1. Adapting a pushrod block for overhead cams was difficult, and the 60? vee angle made this a very tall engine, but power output was impressive.

[93JC]

DOHC 3.4L?!

I didn't believe it at first, but I looked it up and sure enough GM used a DOHC V6 in the Monte Carlo. Seems really strange.

Yeah, dude, they had a V6 way back in the day with four camshafts and 24 valves. Sounds crazy, I know.

It was their bad-ass V6 engine that took on the Ford/Yamaha SHO V6. 205-215 hp, depending on application.  It was used for many years in the W-body cars (save the Buick Regal, which used the 175-200 hp 3800 instead).

Believe it or not the most bad-ass of all Chevrolet Luminas, the Z34, was equipped with the "Twin Dual Cam" V6 and, of all things, a 5-speed manual gearbox.

In a Lumina!

[93JC]

I'm assuming it's the LQ1:

Quoted from:
http://en.wikipedia.org/wiki/GM_60-Degree_V6_engine

The LQ1 (also called the Twin Dual Cam) was a special DOHC version of the 3.1 L LH0 V6. It was built from 1991 to 1997. 1991-1993 it used tuned multiport fuel injection, made 200-210 hp @ 5,200 rpm and 215 ft. lbs torque @ 4000 rpm. 1994-1997 it used sequential fuel injection (SFI) making 215 hp @ 5,200 rpm and 225 ft. lbs torque @ 4,000 rpm. It has four large valves per cylinder. The 3.4 L uses a cogged belt to drive the four overhead camshafts. The gearbox options for the LQ1 were a 4 speed Hydra-Matic electronic shifting transmission and a 5 speed Getrag 284 manual transmission, unique to the LQ1. Adapting a pushrod block for overhead cams was difficult, and the 60? vee angle made this a very tall engine, but power output was impressive.

I stand corrected.

[AutobahnSHO]

Yeah, dude, they had a V6 way back in the day with four camshafts and 24 valves. Sounds crazy, I know.

It was their bad-ass V6 engine that took on the Ford/Yamaha SHO V6. 205-215 hp, depending on application.? It was used for many years in the W-body cars (save the Buick Regal, which used the 175-200 hp 3800 instead).

Believe it or not the most bad-ass of all Chevrolet Luminas, the Z34, was equipped with the "Twin Dual Cam" V6 and, of all things, a 5-speed manual gearbox.

In a Lumina!

Pfft.  Still SHO-pwned.    

[93JC]

... and SHO got pwned by a lowly four-banger Dodge.



:P

[SaltyDog]

It could be normal, and maybe you never noticed it and/or the cold air(which the car hasn't seen before?) triggers it.  GM engines like to make ugly noises, as I can attest.

[AutobahnSHO]

... and SHO got pwned by a lowly four-banger Dodge.



:P

BOOOOOOOOST

Doesn't really compare- they're extinct.  The SHO lives on.   
"Just 1,208 Spirit R/Ts, all built in Mexico, were produced in 1991 ? 774 red ones and 434 in white. An additional 191 were built in 1992 ? 92 red, 68 white, and 31 silver." 
http://en.wikipedia.org/wiki/Dodge_Spirit

[Rupert]

Yeah, dude, they had a V6 way back in the day with four camshafts and 24 valves. Sounds crazy, I know.

It was their bad-ass V6 engine that took on the Ford/Yamaha SHO V6. 205-215 hp, depending on application.  It was used for many years in the W-body cars (save the Buick Regal, which used the 175-200 hp 3800 instead).

Believe it or not the most bad-ass of all Chevrolet Luminas, the Z34, was equipped with the "Twin Dual Cam" V6 and, of all things, a 5-speed manual gearbox.

In a Lumina!

C'mon, we all know the Lumina is the best luxury car of the last twenty years, so it's no wonder that it had the best engine as well.

[AutobahnSHO]

C'mon, we all know the Lumina is the best luxury car of the last twenty years, so it's no wonder that it had the best engine as well.

PFFFT.
The SHO had a good 5-15hp more.  3.0L baby!!

[TurboDan]

It could be normal, and maybe you never noticed it and/or the cold air(which the car hasn't seen before?) triggers it.  GM engines like to make ugly noises, as I can attest.

Haha, whenever it gets cold out, the Saab makes a tiny little high pitched "purr" between 40 and 45MPH.  It freaked me out when I first got it, but I don't notice it anymore.

[giant_mtb]

So me and a buddy checked it out the other day.  He knows a lot about cars...his dad owns a car dealership and he's worked on cars his whole life.  He's dumbfounded.  The noise is only under load (in gear) and is dependent on engine speed.  So it's not half-shafts.  He thinks it MIGHT be a valve that's off-time...?  I don't know.  It's just ridiculously annoying because the range of RMPs at which this noise occurs is THE area of the tach that I spend the most time in.  At least for acceleration.  Though, I usually avoid that range as much as possible...so I'm either accelerating slowly under 2250 RPMs or accelerating more briskly above 3000 RPM...never at a normal pace.   

[AutobahnSHO]

 
I had an 83 Honda that rattled forever, but it was at all speeds, just louder sometimes. Took it to the shop and before the guy came outside said it was probably the waterpump.  Sure enough, replaced it and it was fine. He said I was lucky it didn't blow on the way over, I'd been driving it like that for 9 months!!