Need help diagnosing high pitch noise from engine, video attached
12-07-2017, 10:19 AM
#1
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Need help diagnosing high pitch noise from engine, video attached
i started noticing a high pitch squeal noise almost like the belt is making noise. I figured it was the idler pulleys, so I pulled the belt off, and sure enough the pulleys were loose and rough when spinning them. So i installed all new pulleys and a new belt and drove to work this morning. Low and behold it's still making the same noise. It only happens on decel or at slow engine speeds. And it's definitely engine speed related. What other bearing or component could be making the noise??
12-07-2017, 10:42 AM
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2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Did you change out the tensioner?
12-07-2017, 10:50 AM
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12-07-2017, 10:54 AM
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BLKROKT (12-07-2017)
12-11-2017, 10:18 AM
#5
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Changed out the tensioner. That was a real pain. Had to remove the radiator fan to get enough room to pull out the tensioner. Bad news though. It didn't eliminate the noise. I just ordered a mechanic stethoscope so I can try and pin point where the noise is coming from. It only does it when it is warm and the engine is either decelerating or running below 1500 rpms or so. Pretty pissed I wasted the $ and time thus far. I'll give it one last shot with the stethoscope.
12-11-2017, 01:34 PM
#6
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ok ill take a stab since BLKRKT was of zero assistance(Jesus Jim...)
i had a VERY similar sound that i thought was rotational as well, but as it turns out it was coming from one of 2 places(moved both while cleaning out intake so not sure which fixed it)...on the rear driver side of the manifold there are 2 vacuum fittings, one is a snap fitting(top) while the other just pushes into a rubber connector. My guess would be that it was the lower one as it is not JUST a solid line you are pushing the plastic hose into from the outside, on the inside of the manifold there is another hose that feeds the throttle bodies. This hose pushes in from the inside while the plastic hose pushes in from the back. I think that somehow the inner hose had come unseated from the rubber boot/coupling and that was causing the chirp/whistle. I actually just fixed mine last night when i pulled the manifold off and went through it top to bottom.......
i had a VERY similar sound that i thought was rotational as well, but as it turns out it was coming from one of 2 places(moved both while cleaning out intake so not sure which fixed it)...on the rear driver side of the manifold there are 2 vacuum fittings, one is a snap fitting(top) while the other just pushes into a rubber connector. My guess would be that it was the lower one as it is not JUST a solid line you are pushing the plastic hose into from the outside, on the inside of the manifold there is another hose that feeds the throttle bodies. This hose pushes in from the inside while the plastic hose pushes in from the back. I think that somehow the inner hose had come unseated from the rubber boot/coupling and that was causing the chirp/whistle. I actually just fixed mine last night when i pulled the manifold off and went through it top to bottom.......
12-11-2017, 02:51 PM
#7
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Thx. I'll take a look and see if those locations are making the noise. It sounded more like it was coming from the belt area, but hopefully the stethoscope will help pinpoint it. Thx!!
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12-11-2017, 02:56 PM
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Changed out the tensioner. That was a real pain. Had to remove the radiator fan to get enough room to pull out the tensioner. Bad news though. It didn't eliminate the noise. I just ordered a mechanic stethoscope so I can try and pin point where the noise is coming from. It only does it when it is warm and the engine is either decelerating or running below 1500 rpms or so. Pretty pissed I wasted the $ and time thus far. I'll give it one last shot with the stethoscope.
It's air being sucked through the front main seal.
crack the oil cap or pull out the dipstick with the engine running and the noise will go away.
The problem is that the PVC breather hose that goes from the back of the connection on the block.
Thanks
Dave
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Mort (12-19-2017)
12-12-2017, 07:29 AM
#11
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i know that i didnt when i changed mine....if i recall correctly all i had to do was remove 1 T30 torx screw that holds PS reservoir in place, lift and move PS reservoir out of the way and then remove the top idler pulley
12-12-2017, 12:26 PM
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12-18-2017, 02:31 PM
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The noise is definitely coming from the front of the engine around where the drive belt is. The stethoscope didn't really help much as it helps more with faint noises like gears and such.
It only makes the noise when it's warmed up after about 10-12 minutes of driving. Only makes the noise when engine is slowing down or off/really low throttle. At idle it will make the sound too, and the warmer the engine it seems to be louder. At cruising speed it doesn't make the sound.
It's not the cooling fan, because I stopped it from turning and noise was still there.
It only makes the noise when it's warmed up after about 10-12 minutes of driving. Only makes the noise when engine is slowing down or off/really low throttle. At idle it will make the sound too, and the warmer the engine it seems to be louder. At cruising speed it doesn't make the sound.
It's not the cooling fan, because I stopped it from turning and noise was still there.
Edit---Thanks for the post about the front main seal. I will check pulling the dipstick or filler cap to see if that stops it! I didn't try removing the ps reservoir. I got the tensioner loose, but couldn't figure out how to remove it from the area without pulling the fan/housing. Thx guys! I'll keep you posted this afternoon!
Last edited by greginaz; 12-18-2017 at 02:38 PM.
12-19-2017, 10:26 AM
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Pulled the dipstick while it was making the noise. Boom! That made it stop!! I could also hear a pretty good amount of air getting sucked in through the dipstick opening. Wow. So looks like my pcv breather tube is toast. Thanks for the help!!
i found a post on the E class board about replacing it. Here is a picture borrowed from weistec install instructions for their oil catch can. I guess the proper way to replace it is to remove the intake manifold, but it can be done without doing that with a lot of patience and some talented hands to do it blindly.
Looks like Ike I know what I will be doing over xmas vacation.
12-19-2017, 11:00 AM
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12-19-2017, 12:26 PM
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Pulled the dipstick while it was making the noise. Boom! That made it stop!! I could also hear a pretty good amount of air getting sucked in through the dipstick opening. Wow. So looks like my pcv breather tube is toast. Thanks for the help!!
i found a post on the E class board about replacing it. Here is a picture borrowed from weistec install instructions for their oil catch can. I guess the proper way to replace it is to remove the intake manifold, but it can be done without doing that with a lot of patience and some talented hands to do it blindly.
Looks like Ike I know what I will be doing over xmas vacation.
Good stuff! Glad it was an easy one - As Jasonoff said - if you can get the plastic retaining off - it makes the job much easier... It would be worth checking your intake manifold to see if it's leaking, you may want to just do that as well. With the engine HOT, spray some parts/brake cleaner around the base of the intake manifold where it meets the head. If the engine rhythm changes at all, you have an intake leak... Its super common.
Thanks
Dave
12-19-2017, 12:40 PM
#17
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Thx guys. Yes, I will try cutting the connector.
I just had the intake manifold and throttle bodies replaced by the stealership last year, so it should be sealed up tight.
Thanks again for the help! New breather is on the way!
I just had the intake manifold and throttle bodies replaced by the stealership last year, so it should be sealed up tight.
Thanks again for the help! New breather is on the way!
12-19-2017, 01:01 PM
#18
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Clip cut on the connector
Port on block that tube connects to
Breather tube in place with intake manifold removed
clip cut on the connector
Here are a couple pics I stole from the other threads..
12-20-2017, 07:55 AM
#19
Super Member
ok ill take a stab since BLKRKT was of zero assistance(Jesus Jim...)
i had a VERY similar sound that i thought was rotational as well, but as it turns out it was coming from one of 2 places(moved both while cleaning out intake so not sure which fixed it)...on the rear driver side of the manifold there are 2 vacuum fittings, one is a snap fitting(top) while the other just pushes into a rubber connector. My guess would be that it was the lower one as it is not JUST a solid line you are pushing the plastic hose into from the outside, on the inside of the manifold there is another hose that feeds the throttle bodies. This hose pushes in from the inside while the plastic hose pushes in from the back. I think that somehow the inner hose had come unseated from the rubber boot/coupling and that was causing the chirp/whistle. I actually just fixed mine last night when i pulled the manifold off and went through it top to bottom.......
i had a VERY similar sound that i thought was rotational as well, but as it turns out it was coming from one of 2 places(moved both while cleaning out intake so not sure which fixed it)...on the rear driver side of the manifold there are 2 vacuum fittings, one is a snap fitting(top) while the other just pushes into a rubber connector. My guess would be that it was the lower one as it is not JUST a solid line you are pushing the plastic hose into from the outside, on the inside of the manifold there is another hose that feeds the throttle bodies. This hose pushes in from the inside while the plastic hose pushes in from the back. I think that somehow the inner hose had come unseated from the rubber boot/coupling and that was causing the chirp/whistle. I actually just fixed mine last night when i pulled the manifold off and went through it top to bottom.......
BOOM.....
.....and its not difficult to change the pcv with the manifold in place, remove the lower hose while standing on the driver side reaching down the firewall(not through the other wiring/tubing) and then the upper bracket while standing on the passenger side....is 1000x easier if you remove the airboxes and y-snorkel
12-24-2017, 10:30 AM
#20
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Loosen hidden bolts circled in green with special T45 torx bit
I had to buy the bit on the left. The standard on the right wouldn't fit.
View if clip on breather pipe connector.
Another view of clip
Bad seal inside breather. See hole in orange rubber flap.
I got the breather pipe changed! Patience is key if you're not wanting to remove the intake manifold. Which I left in place since it was removed not to long ago. I tried cutting the clip, but wasn't able to. I used a small screwdriver to get under the clip and just broke the clip with leverage. The plastic was pretty brittle so it popped free.
Then I tried removing the lower tube and it's impossible without loosening the bolts that hold the coolant cross pipe in place. The other posts don't mention that. So be prepared with a long or skinny T45 torx bit to access the hold down bolts. See pic below. Don't completely remove the bolts, just loosen them enough so you can move the coolant pipe for enough clearance to get breather pipe free, and install the new one.
I was curious how the breather failed, so I took it apart. It looks like a 1 way diaphragm valve and the rubber seal broke out basically keeping it open and allowing the intake to suck air from crankcase.
Last edited by greginaz; 12-24-2017 at 01:03 PM.
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BLKROKT (12-24-2017)
12-24-2017, 12:59 PM
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12-24-2017, 01:15 PM
#24
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BOOM.....
.....and its not difficult to change the pcv with the manifold in place, remove the lower hose while standing on the driver side reaching down the firewall(not through the other wiring/tubing) and then the upper bracket while standing on the passenger side....is 1000x easier if you remove the airboxes and y-snorkel
.....and its not difficult to change the pcv with the manifold in place, remove the lower hose while standing on the driver side reaching down the firewall(not through the other wiring/tubing) and then the upper bracket while standing on the passenger side....is 1000x easier if you remove the airboxes and y-snorkel
i already did....
