Loud Engine Room ? (Page 1/2)
Yellow-88 SEP 21, 01:52 PM
Is it me or are Fiero engine compartments loud? Both of our Fiero's just seem louder than both a 2007 VW and a 2004 Dodge truck. Is it because the exhaust pipes are close by, mixing with and amplifying the engine mechanical sounds? Are individual sound waves mushing together to make extra audio mud? They sound really nice on the road and from a distance but standing near the rear end with the deck open sounds loud and a bit "messy" and "grumbly."

I spent some time listening with a stethoscope to all 4 vehicle engine compartments, alternators and water pumps in particular and I think that GM alternators are the loudest by far. Kind of a growl whine. Both Fiero water pumps are loud and a bit crunchy but are not showing any issues. The Dodge and VW alternators just sing with a classic electric motor sound and pumps sound like pumps. Of course, the exhaust pipes are 10 feet away on those.

Just wondering if I'm alone on this observation.
cartercarbaficionado SEP 21, 03:26 PM

quote
Originally posted by Yellow-88:

Is it me or are Fiero engine compartments loud? Both of our Fiero's just seem louder than both a 2007 VW and a 2004 Dodge truck. Is it because the exhaust pipes are close by, mixing with and amplifying the engine mechanical sounds? Are individual sound waves mushing together to make extra audio mud? They sound really nice on the road and from a distance but standing near the rear end with the deck open sounds loud and a bit "messy" and "grumbly."

I spent some time listening with a stethoscope to all 4 vehicle engine compartments, alternators and water pumps in particular and I think that GM alternators are the loudest by far. Kind of a growl whine. Both Fiero water pumps are loud and a bit crunchy but are not showing any issues. The Dodge and VW alternators just sing with a classic electric motor sound and pumps sound like pumps. Of course, the exhaust pipes are 10 feet away on those.

Just wondering if I'm alone on this observation.



they aren't too refined but not that bad. the water pumps should run pretty much dead silent and the alternators really just softly whine with electrical noise. so maybe repack the bearings on it
I know the 84 and 87 have benefitted the most from the repacking and replacement of pumps
82-T/A [At Work] SEP 21, 05:32 PM

quote
Originally posted by Yellow-88:

Is it me or are Fiero engine compartments loud? Both of our Fiero's just seem louder than both a 2007 VW and a 2004 Dodge truck. Is it because the exhaust pipes are close by, mixing with and amplifying the engine mechanical sounds? Are individual sound waves mushing together to make extra audio mud? They sound really nice on the road and from a distance but standing near the rear end with the deck open sounds loud and a bit "messy" and "grumbly."

I spent some time listening with a stethoscope to all 4 vehicle engine compartments, alternators and water pumps in particular and I think that GM alternators are the loudest by far. Kind of a growl whine. Both Fiero water pumps are loud and a bit crunchy but are not showing any issues. The Dodge and VW alternators just sing with a classic electric motor sound and pumps sound like pumps. Of course, the exhaust pipes are 10 feet away on those.

Just wondering if I'm alone on this observation.




I've noticed this too, though it's significantly more prevalent on Iron Duke Fieros because, well... those engines are far less refined than the V6/60. I'd say though that when a Fiero gets old... if yours is mostly a low-mileage original... there's a lot that starts to wear out and make noise. The injectors (for one), make lots of ticking noises... which can only be fixed by literally replacing them (even when cleaned they're still "worn"). The exhaust system is also much thinner at the manifolds, and tend to be louder than say, what you'd find with a cast iron log type of exhaust manifold.

I don't know about the alternators, as I've never seen anything different (it's been a LONG time since my V6 Fiero ran, and it's still in storage). But I know you already have the new CS130 alternator... so probably no huge improvement there. You could always go with a decoupler pulley... that's something that modern cars have which reduces the feedback from the belt and accessories.

This is the thread where I bought and tried several until I found one that fit ours exactly: https://www.fiero.nl/forum/Forum2/HTML/147741.html

Note, this is a one-way decoupler pulley... so it only decouples on down-shifts... or half the feedback from the belt system. Note, this is a 6-groove... which would work, but the V6/60 only uses a 5-groove (something I think I want to fix when I get my Fiero going again).

There are other decoupler pulleys, which decouple slightly (spring loaded, if you will) both directions. Your Volkswagen would have this on it (my wife's 2004 VW Beetle had it years ago). I can't remember if that's OAP or OAD. But it does help.


All in all though, I think with the Fiero, you have both the exhaust and the engine in the same place... so the sound is distorting eachother, which is much different than a car where the exhaust is on the complete opposite side of the car from the engine. The V6/60, especially the 88 (internally balanced) is a very smooth engine. I think you're aware of the harmonics and balance of 60 degrees being nearly perfect (which is what Ferrari uses). I think it's just everything else. You simplify the motor, and modernize some of the components, and it should improve. The Fiero V6 didn't sound rackety when it was new. I bought my 1987 Fiero SE / V6 in 1996. It had... 52k miles on it, and had sat mostly in storage from a CIA person who was overseas for much of the time he had it. When I used to drive around, it was VERY, VERY quiet.


Of course, sound deadener is a big component of it too...
Patrick SEP 21, 06:17 PM
The loudest noise in the engine bay of my '84 is the valve train of the duke. The 2.5 4-banger is a rattle-trap at the best of times.

The loudest noise in the engine bay of my Formula is its Getrag 5-spd transmission. It used to be quiet, until it developed the notorious Getrag rattle. In this video I shot of my Formula years ago, all that mechanical racket that sounds like a threshing machine is the transmission (in neutral with the clutch engaged). When the clutch is disengaged (or when in gear), the transmission is perfectly quiet.

[This message has been edited by Patrick (edited 09-21-2024).]

82-T/A [At Work] SEP 21, 10:10 PM

quote
Originally posted by Patrick:

The loudest noise in the engine bay of my '84 is the valve train of the duke. The 2.5 4-banger is a rattle-trap at the best of times.

The loudest noise in the engine bay of my Formula is its Getrag 5-spd transmission. It used to be quiet, until it developed the notorious Getrag rattle. In this video I shot of my Formula years ago, all that mechanical racket that sounds like a threshing machine is the transmission (in neutral with the clutch engaged). When the clutch is disengaged (or when in gear), the transmission is perfectly quiet.



I couldn't really tell... is the Getrag rattle the a-synchronous tapping noise I'd occasionally hear in your video?
Patrick SEP 21, 10:19 PM

quote
Originally posted by 82-T/A [At Work]:

I couldn't really tell... is the Getrag rattle the a-synchronous tapping noise I'd occasionally hear in your video?



Try to screen out/ignore the sound of the exhaust. All the repetitive metallic "tapping" noise is the transmission. It almost sounds like loose lifters, but it isn't. My PC is connected to my stereo system, so I get the full effect of this racket. If this video is being watched/listened to on a phone, well, what's the point.

Maybe someday I'll set the camera on a tripod, and shoot a video of the engine bay while I step the clutch in and out. It's actually quite astonishing how much noise my (and many other's) Getrag makes with the clutch engaged while out of gear. Engine running, of course. Whether anyone else notices the racket or not, I'm somewhat embarrassed at a stop light (but not enough to be disengaging the clutch the whole time while stopped).

[This message has been edited by Patrick (edited 09-21-2024).]

82-T/A [At Work] SEP 22, 07:43 AM

quote
Originally posted by Patrick:

Try to screen out/ignore the sound of the exhaust. All the repetitive metallic "tapping" noise is the transmission. It almost sounds like loose lifters, but it isn't. My PC is connected to my stereo system, so I get the full effect of this racket. If this video is being watched/listened to on a phone, well, what's the point.

Maybe someday I'll set the camera on a tripod, and shoot a video of the engine bay while I step the clutch in and out. It's actually quite astonishing how much noise my (and many other's) Getrag makes with the clutch engaged while out of gear. Engine running, of course. Whether anyone else notices the racket or not, I'm somewhat embarrassed at a stop light (but not enough to be disengaging the clutch the whole time while stopped).




No, I wasn't listening to it on a phone. I used to have a really nice 5.1 surround on my computer, but for the past... I dunnno, 7 years, I just have a pair of headphones. I hear ticking that sounds like the injectors, but I do hear a non-synchronous sound, almost like an out of synch rattle... I'm just wondering if that's what you mean.

My Fiero, as I parked it, had a similar sound... but DEFINITELY more pronounced than yours. But I more or less hear something like this from your engine:

[youtube]https://www.youtube.com/watch?v=XketOP_lTO8 [/youtube]


For reference, I took that video about 14 years ago, just before I was about to put it into storage and change careers. It does not have a Getrag in it, it has the automatic Th125, but I'd recently rebuilt the engine and dropped it back in there. I was less experienced working on cars, so I cut some corners without realizing it. For one, I didn't use a torque wrench on the flywheel bolts, and also didn't use thread locker on them either. So that sound you hear (I later learned) are loosening flywheel bolts... lol!!!

I'm planning on swapping in a 5-Speed Getrag with a new motor anyway... but I'm just wondering what exactly is it in the Getrag that is making that noise? I have three Getrags... one with 30k miles on it, then one which is the SCX / Quad-4 and a high mileage Getrag. I was planning on rebuilding the SCX and using parts from the high mileage one... but if there's something I can fix while I've got it open to help prevent that, I'd love to know what it is. Like Yellow-88, when I get to working on my Fiero, I'd really like it to be its "best self" so to speak, and make it perfect... quiet, refined, etc... as it should be.

[This message has been edited by 82-T/A [At Work] (edited 09-22-2024).]

fieroguru SEP 22, 09:39 AM
GM and other mfg. put a large focus on NVH (noise, vibration, and harshness) in the 90s and made huge strides.

One of the big things is the use of engine covers to help reduce the sound of the injectors and valvetrain noises. They also added silencers and plastic air intake filters to cut down on air flow/iac noise.
claude dalpe SEP 22, 05:07 PM
I also have a getrag on my 1987 of 200,000Km

when I had my original 2.8 it was noisy but since I did my 3.5LX9 swap (about 10 years) the engine runs very smoothly and I barely hear it

the time I did my tune I heard it a lot more like with my 2.8
Patrick SEP 22, 05:29 PM

quote
Originally posted by 82-T/A [At Work]:

My Fiero, as I parked it, had a similar sound... but DEFINITELY more pronounced than yours. But I more or less hear something like this from your engine:




No no no... fortunately there's nothing in my video that even sounds remotely like that. Those loose flexplate bolts you had are responsible for a much "heavier" sound.


quote
Originally posted by 82-T/A [At Work]:

I'm planning on swapping in a 5-Speed Getrag with a new motor anyway... but I'm just wondering what exactly is it in the Getrag that is making that noise?



A search for "Getrag rattle" will turn up all sorts of threads. There's been a lot of debate on the cause and on a possible solution over the years. Some people have reported a measure of success by changing to various types/grades of oil.