Intake chirp and rev whine - please help diagnose these sound clips
08-10-2018, 02:36 AM
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Intake chirp and rev whine - please help diagnose these sound clips
Hi guys,
I have separate clips of two different, but annoying and maybe concerning noises that I'm clueless on.
The first is a chirp upon an initial blip of the throttle seemingly coming from the air intake. I am de-snorkeled.
The second is a whine that corresponds with the engine's revs. It's the same whether in gear or in neutral, clutch in or out. I installed a 997 shifter today and don't recall hearing the sound previously, but I could be wrong. I recently had my water pump replaced. Could it be the serpentine belt? It's not the transmission right, since it's the same whether in or out of gear?
Sorry for the crappy videos, but I didn't know how else to record the sound. Thanks in advance for any help you can offer!
I have separate clips of two different, but annoying and maybe concerning noises that I'm clueless on.
The first is a chirp upon an initial blip of the throttle seemingly coming from the air intake. I am de-snorkeled.
The second is a whine that corresponds with the engine's revs. It's the same whether in gear or in neutral, clutch in or out. I installed a 997 shifter today and don't recall hearing the sound previously, but I could be wrong. I recently had my water pump replaced. Could it be the serpentine belt? It's not the transmission right, since it's the same whether in or out of gear?
Sorry for the crappy videos, but I didn't know how else to record the sound. Thanks in advance for any help you can offer!
08-10-2018, 06:33 PM
#4
Race Director
Can't really listen at the office.Too noisy.
If the noises are present at cold engine start you can remove the serpentine belt -- carefully note the routing and the direction the belt rotates so you can put the belt back on exactly like it came off -- and start the engine and let it idle or give it some gas just long enough to confirm the noise(s) is (are) still present or not.
The result of the above test if you can do it will help you decide what to do next.
Certainly if the noises are not present with the belt removed this strongly suggests the source of the noise is the accessory drive.
My Boxster's water pump initially made itself known by the presence of a low volume low frequency rumbling noise that got louder as the cold engine ran and things warmed up. I removed the belt and the noise was no longer present. With the belt off I checked and found some play at the water pump. Not much but clearly there was play at the water pump while the other drives had no play.
I note in your case the water pump was recently replaced. A bad water pump can take a toll on the belt. It is best when replacing a water (and T-Stat) to replace the serpentine belt.
Less likely but something you have to keep in mind is a replacement water pump can be bad, go bad. (Non OE water pumps appear to have a tendency to fail sooner rather than later. Not all but enough that one can't dismiss the water pump (even a new one) from being a source of the noise.)
Before you install a new belt check all accessories for any bearing play. In my experience a bad water pump won't have that much bearing play but it will have play compared to the other accessories which won't have any. The same applies to other accessory drives. Any real play -- axial or radial -- is cause for real concern the accessory is worn out.
Do not forget to check the idler roller and tensioner rollers for any bearing play or signs of bearing (seal) degradation.
An intermittent and faint "chirp" in my experience with my 996 Turbo proved to be a bad idler roller bearing. In another case of a bad idler roller bearing the noise was a "dry bearing" noise.
As for a possible bad AOS, with my Boxster none of the 3 failed AOS's manifested any noise. However, the engine sure manifested signs of a problem due to intake air leak (un-metered air) that the failing AOS allowed to get to the intake manifold.
If the noises are present at cold engine start you can remove the serpentine belt -- carefully note the routing and the direction the belt rotates so you can put the belt back on exactly like it came off -- and start the engine and let it idle or give it some gas just long enough to confirm the noise(s) is (are) still present or not.
The result of the above test if you can do it will help you decide what to do next.
Certainly if the noises are not present with the belt removed this strongly suggests the source of the noise is the accessory drive.
My Boxster's water pump initially made itself known by the presence of a low volume low frequency rumbling noise that got louder as the cold engine ran and things warmed up. I removed the belt and the noise was no longer present. With the belt off I checked and found some play at the water pump. Not much but clearly there was play at the water pump while the other drives had no play.
I note in your case the water pump was recently replaced. A bad water pump can take a toll on the belt. It is best when replacing a water (and T-Stat) to replace the serpentine belt.
Less likely but something you have to keep in mind is a replacement water pump can be bad, go bad. (Non OE water pumps appear to have a tendency to fail sooner rather than later. Not all but enough that one can't dismiss the water pump (even a new one) from being a source of the noise.)
Before you install a new belt check all accessories for any bearing play. In my experience a bad water pump won't have that much bearing play but it will have play compared to the other accessories which won't have any. The same applies to other accessory drives. Any real play -- axial or radial -- is cause for real concern the accessory is worn out.
Do not forget to check the idler roller and tensioner rollers for any bearing play or signs of bearing (seal) degradation.
An intermittent and faint "chirp" in my experience with my 996 Turbo proved to be a bad idler roller bearing. In another case of a bad idler roller bearing the noise was a "dry bearing" noise.
As for a possible bad AOS, with my Boxster none of the 3 failed AOS's manifested any noise. However, the engine sure manifested signs of a problem due to intake air leak (un-metered air) that the failing AOS allowed to get to the intake manifold.
08-10-2018, 07:47 PM
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Can't really listen at the office.Too noisy.
If the noises are present at cold engine start you can remove the serpentine belt -- carefully note the routing and the direction the belt rotates so you can put the belt back on exactly like it came off -- and start the engine and let it idle or give it some gas just long enough to confirm the noise(s) is (are) still present or not.
The result of the above test if you can do it will help you decide what to do next.
Certainly if the noises are not present with the belt removed this strongly suggests the source of the noise is the accessory drive.
My Boxster's water pump initially made itself known by the presence of a low volume low frequency rumbling noise that got louder as the cold engine ran and things warmed up. I removed the belt and the noise was no longer present. With the belt off I checked and found some play at the water pump. Not much but clearly there was play at the water pump while the other drives had no play.
I note in your case the water pump was recently replaced. A bad water pump can take a toll on the belt. It is best when replacing a water (and T-Stat) to replace the serpentine belt.
Less likely but something you have to keep in mind is a replacement water pump can be bad, go bad. (Non OE water pumps appear to have a tendency to fail sooner rather than later. Not all but enough that one can't dismiss the water pump (even a new one) from being a source of the noise.)
Before you install a new belt check all accessories for any bearing play. In my experience a bad water pump won't have that much bearing play but it will have play compared to the other accessories which won't have any. The same applies to other accessory drives. Any real play -- axial or radial -- is cause for real concern the accessory is worn out.
Do not forget to check the idler roller and tensioner rollers for any bearing play or signs of bearing (seal) degradation.
An intermittent and faint "chirp" in my experience with my 996 Turbo proved to be a bad idler roller bearing. In another case of a bad idler roller bearing the noise was a "dry bearing" noise.
As for a possible bad AOS, with my Boxster none of the 3 failed AOS's manifested any noise. However, the engine sure manifested signs of a problem due to intake air leak (un-metered air) that the failing AOS allowed to get to the intake manifold.
If the noises are present at cold engine start you can remove the serpentine belt -- carefully note the routing and the direction the belt rotates so you can put the belt back on exactly like it came off -- and start the engine and let it idle or give it some gas just long enough to confirm the noise(s) is (are) still present or not.
The result of the above test if you can do it will help you decide what to do next.
Certainly if the noises are not present with the belt removed this strongly suggests the source of the noise is the accessory drive.
My Boxster's water pump initially made itself known by the presence of a low volume low frequency rumbling noise that got louder as the cold engine ran and things warmed up. I removed the belt and the noise was no longer present. With the belt off I checked and found some play at the water pump. Not much but clearly there was play at the water pump while the other drives had no play.
I note in your case the water pump was recently replaced. A bad water pump can take a toll on the belt. It is best when replacing a water (and T-Stat) to replace the serpentine belt.
Less likely but something you have to keep in mind is a replacement water pump can be bad, go bad. (Non OE water pumps appear to have a tendency to fail sooner rather than later. Not all but enough that one can't dismiss the water pump (even a new one) from being a source of the noise.)
Before you install a new belt check all accessories for any bearing play. In my experience a bad water pump won't have that much bearing play but it will have play compared to the other accessories which won't have any. The same applies to other accessory drives. Any real play -- axial or radial -- is cause for real concern the accessory is worn out.
Do not forget to check the idler roller and tensioner rollers for any bearing play or signs of bearing (seal) degradation.
An intermittent and faint "chirp" in my experience with my 996 Turbo proved to be a bad idler roller bearing. In another case of a bad idler roller bearing the noise was a "dry bearing" noise.
As for a possible bad AOS, with my Boxster none of the 3 failed AOS's manifested any noise. However, the engine sure manifested signs of a problem due to intake air leak (un-metered air) that the failing AOS allowed to get to the intake manifold.
08-11-2018, 04:46 PM
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Took the serpentine belt off and the whine is still there. I wonder if it's normal. Or could it be transmission related? I do hear a rattling in the there that sounds like I may have a loose spark plug. I'll tackle that tomorrow. Thanks again for any and all input.
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08-11-2018, 07:44 PM
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08-13-2018, 11:46 AM
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Took the serpentine belt off and the whine is still there. I wonder if it's normal. Or could it be transmission related? I do hear a rattling in the there that sounds like I may have a loose spark plug. I'll tackle that tomorrow. Thanks again for any and all input.
https://youtu.be/xcQSeeC__Sg
https://youtu.be/xcQSeeC__Sg
If the noise is not considered normal and it is not from the accessory drive you are looking at a large expense because that leaves the noise coming from the transmission -- if a manual possibly the release bearing -- or from the engine. A transmission drop could be in the car's future and you want to be darn sure that's called for.
Regarding the rattling noise: If you believe the rattling noise is a plug loose that could account for the "chirping" noise too.
08-13-2018, 11:51 AM
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Best advice I can offer is to get the car in and lifted up and let a professional give a listen, assuming he believes the whining noise is not normal. Honestly I'm too far past my Boxster ownership to recall what sounds normal and what doesn't. But if it is not normal being able to pinpoint where the noise comes from helps to better diagnosis what's likely going on.
If the noise is not considered normal and it is not from the accessory drive you are looking at a large expense because that leaves the noise coming from the transmission -- if a manual possibly the release bearing -- or from the engine. A transmission drop could be in the car's future and you want to be darn sure that's called for.
Regarding the rattling noise: If you believe the rattling noise is a plug loose that could account for the "chirping" noise too.
If the noise is not considered normal and it is not from the accessory drive you are looking at a large expense because that leaves the noise coming from the transmission -- if a manual possibly the release bearing -- or from the engine. A transmission drop could be in the car's future and you want to be darn sure that's called for.
Regarding the rattling noise: If you believe the rattling noise is a plug loose that could account for the "chirping" noise too.
08-13-2018, 11:54 AM
#11
Race Director
Thank you, I really appreciate the detail. I'll take the serpantine belt off tomorrow morning and will see what happens from there. Just to be clear (and I probably should have separated the threads), I'm dealing with two different noises. One is a chirp when the throttle is blipped that sounds like a sucking sound with the engine cover off. The second is a whine that goes along with the revs of the engine.
There is some kind of vacuum/low pressure test (measurement) that can be done and is reported to be good at confirming a bad AOS. I don't have the details handy but a search should turn up the test. Briefly, the crankcase vacuum/pressure is measured at hot idle and it is too low this is a sign the AOS is failing (has failed).
Another "test" is to with the engine idling at operating temperature unscrew and remove the oil filler tube cap. In some cases, if the AOS failure has advanced enough, the cap can be impossible to remove against the pressure difference. If you are able to remove the cap this does not give the AOS a clean bill of health, though.
While you are there be sure the oil filler tube cap is not leaking. With the engine idling see if you can move the cap around if there is any play or even lift it up. What I have found -- two times -- is the cap seal appears to age/shrink and while the cap is secure the seal doesn't make good contact and the cap represents an intake air leak. A small one that is only really an issue at idle. But it should be addressed and a new cap is the fix.