Engine squealing?

1961-1968: a.k.a "Finnie" or "Heckflosse" models
190, 190D, 200, 200D, 220b, 220Sb, 220SEb, 230, 230S, 250SE coupe, 280SE coupe, 280SE 3.5 coupe, 220SEb cabrio., 250SE conv., 280SE cabrio., 280SE 3.5 Cabrio., 300SE, 300SE coupe, 300SE conv., 300SEL
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Jeremy
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Engine squealing?

Post by Jeremy » Sat 08 Jul, 2017 7:19 pm

I've been dealing with an annoying squealing noise coming from my engine bay which has been getting progressively worse over the last few weeks. I strongly suspected it was the generator bearings so I replaced them, no change. The noise only seems to happen when in gear and on overrun or light throttle, cant replicate by revving in park which means I cant stick my head in the engine bay to find out where its coming from. It doesn't change in pitch at different speed or engine rpm, and its definitely nothing like a belt slipping. The overrun thing has me thinking it might be something to do with a worn thrust bearing on the crank? but there's no appreciable end play when i tug on the pulley. I did the stethoscope thing on my water pump and generator they both sound ok so far as i can tell. anybody have any fresh ideas?
1965 220Sb

ChristoC
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Engine squealing?

Post by ChristoC » Sun 09 Jul, 2017 6:32 am

Squeals almost sure to be belt or belt tensioner idler; try sprinkling baby powder or talcum liberally on belt & pulleys; does the squeal go away?


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CraigB
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Re: Engine squealing?

Post by CraigB » Sun 09 Jul, 2017 11:45 am

my thoughts too but I didn't respond because it said definitely not a belt. I would think anything rotating is going to be affected by engine speed and sounds like it isn't. What about vacuum or manifold leak. A leak in an exhaust manifold gasket can sound like a tap, not really a squeal though. I don't know your model well so don't know how much vacuum is on it - modulator, distributor? If you have done generator, i would wonder about waterpump. Does it matter how warm the car is? Strange you can replicate. Something in the trans too maybe that is somehow bouncing that sound forward.

Just plucking at straws here in case it triggers thoughts.
Craig Baulderstone
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Bartman4800
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Re: Engine squealing?

Post by Bartman4800 » Mon 10 Jul, 2017 11:11 am

Jeremy,

Can you post a soundbite on youtube and share the link here?
We can give you some better ideas then.

When you say in gear, that means your clutch is depressed? Or do you have an automatic box

If manual, that would indicate a problem with your clutch throw-out bearing.

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

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pastelgrey300D
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Re: Engine squealing?

Post by pastelgrey300D » Mon 10 Jul, 2017 12:34 pm

Check your generator mount bushings - I had a squeal from my car which was caused by disintegrated generator mount bushings, allowing metal-to-metal contact - it had actually started to wear the generator mounting hole into an oval shape. Check to see if the generator is solidly mounted, if you can move or rattle it by hand then the mounts are shot.

Another one could be water pump bearings. Try disconnecting the fan belt to see if you can eliminate the water pump?
David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

CraigB
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Re: Engine squealing?

Post by CraigB » Tue 11 Jul, 2017 12:48 am

That's a great idea to remove belt, but do it when cold for a very short amount of time and can pinpoint if any of those belt driven things.

I see your signature photos were hosted in photobucket - amazing how many times you see that photobucket symbol now - probably a reminder to those in the company what idiots they were to destroy their own company! (from what i read elsewhere that experts saying the experience has permanently damaged their 'brand' - but the reminders are everywhere and constant)
Craig Baulderstone
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pastelgrey300D
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Re: Engine squealing?

Post by pastelgrey300D » Tue 11 Jul, 2017 11:32 am

I see your signature photos were hosted in photobucket - amazing how many times you see that photobucket symbol now - probably a reminder to those in the company what idiots they were to destroy their own company! (from what i read elsewhere that experts saying the experience has permanently damaged their 'brand' - but the reminders are everywhere and constant)
Yeah, very annoyed about that - not so much for pictures of my own cars etc but for the loss of pictures from several of the how-to pictorials I've posted on here (such as the vacuum central locking repair and reverse light repair threads). Also annoying more so on other forums where I don't have the opportunity to attach pictures to threads and all of my images have been linked across from photobucket. :cussing:
David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

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Jeremy
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Re: Engine squealing?

Post by Jeremy » Tue 11 Jul, 2017 7:32 pm

Thanks for all your suggestions, and I did try the other day to record the sound as I was driving. Unfortunately the audio quality from my phone is terrible so its not much help. In trying to record the noise though I drove up the freeway next to a big concrete wall and was able to listen to the sound a bit more clearly. It did actually change with my speed but the pitch was the same (or frequency maybe, not a sound engineer). What I took from it was that it was more like a clicking sound that was blurring into a high pitched squeal at speed. Now I'm thinking drive train possibly a wheel bearing in the front. Haven't had time to investigate further yet but its progress, I think. Will keep you posted.

PS. Its an auto so no throw-out bearing to speak of, just endless ATF leaks
1965 220Sb

merc-304
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Re: Engine squealing?

Post by merc-304 » Tue 11 Jul, 2017 9:46 pm

I had a dodgy Universal joint that made these sounds ..bizarre and hard to pinpoint where the source was.
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Re: Engine squealing?

Post by CraigB » Tue 11 Jul, 2017 10:42 pm

I'm thinking water pump from what you have said. Lower revs ok and then with sustained spinning heating and gripping and then the squeal. This happened on my pagoda, but was pretty clear that was what it was. If it does that at speed and then you pull over, put it in neutral and then rev, you would expect it to do that again.

Wheel bearing you will normally feel something back through the wheel i think, but then that is from normal cars and maybe the benz isolates it? you would expect to feel play when jacked and off ground and hear rumble when you spin it. Uni joint will normally get a vibration and often noise as you change from R to D.

Just more thinking out loud!
Craig Baulderstone
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Jeremy
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Re: Engine squealing?

Post by Jeremy » Wed 19 Jul, 2017 7:03 pm

I feel like I just photographed bigfoot! After trying about 10 different ways to record the noise, I ended up just filming a video on my phone and the noise came through fine. It's most noticeable when I get to the concrete barrier as the road turns into freeway, about 30 seconds in. You can also hear that it disappears as soon as I started accelerating from 60 to 80.

https://youtu.be/qTcFrOSn7hM

I still haven't had much chance to look under the car but I jacked up the left front side and spun the wheel a few times, no grumbly bearings. Also I had my driveshaft rebuilt with new unis earlier this year so I'm mostly sure its not that.
1965 220Sb

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Bartman4800
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Re: Engine squealing?

Post by Bartman4800 » Wed 19 Jul, 2017 7:25 pm

I heard it loud and clear. Sounds like a very dry bearing.

Did you have the centre bearing on the propshaft replaced?

You say it comes on after a bit of driving, which would suggest the driveline only as a culprit.
Otherwise it would sound when you just rev up the engine.

The output bearing on the gearbox is another possibility.

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

CraigB
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Re: Engine squealing?

Post by CraigB » Wed 19 Jul, 2017 8:48 pm

If you found a big hill, rolled down it in neutral with engine off, you should soon isolate it to drivetrain from output shaft of gearbox/trans backwards. But be prepared for pushing hard on brakes or steering if you have power brakes and steering - or do it on a stretch long enough you can start it again.
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
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Jeremy
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Re: Engine squealing?

Post by Jeremy » Wed 19 Jul, 2017 10:00 pm

I might try that rolling down a hill. I did have a thought about the gearbox output bearing potentially causing the noise. The centre bearing was replaced when the driveshaft was done, but the rebuild didn't sort out the vibration over 100kmh that I was hoping it would. The vibration might have done in the bearing after a few long trips up the coast. What could cause drive-line vibration besides the driveshaft? Something off about the diff? I'm really heading down the rabbit hole now.
1965 220Sb

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pastelgrey300D
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Re: Engine squealing?

Post by pastelgrey300D » Thu 20 Jul, 2017 11:18 am

Just a thought, what about the centering bushing where the driveshaft connects to the gearbox? On a finnie this requires greasing (later cars had nylon bushings). 2 minute job to get under there and squirt some grease in.
driveshaft grease point.JPG
RE: the vibration, check your gearbox mount, if the mount has collapsed or is worn it can cause the driveshaft to be misaligned and this causes vibration.
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David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

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Jeremy
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Re: Engine squealing?

Post by Jeremy » Fri 28 Jul, 2017 10:01 pm

pastelgrey300D wrote:Just a thought, what about the centering bushing where the driveshaft connects to the gearbox? On a finnie this requires greasing (later cars had nylon bushings). 2 minute job to get under there and squirt some grease in.
driveshaft grease point.JPG
RE: the vibration, check your gearbox mount, if the mount has collapsed or is worn it can cause the driveshaft to be misaligned and this causes vibration.
Man knows his bearing noises. I greased up the entire driveshaft last week, didn't have an immediate effect but a week later the noise is gone and I haven't done anything else in the interim. Maybe I need to get under and push some more grease through to be absolutely sure but I think I'm squeak free! Thank you all for your input, but the points allocation is clear :notworthy:
1965 220Sb

merc-304
250s
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Re: Engine squealing?

Post by merc-304 » Fri 28 Jul, 2017 11:21 pm

Sounds like you have fixed your mystery noise..maybe pull that joint apart clean and degrease fit a new grease nipple.
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Mercmad
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Re: Engine squealing?

Post by Mercmad » Sun 30 Jul, 2017 6:00 pm

I was going to say a dry spider bearing in the front of the drive shaft. :think: And the vibration over 100k's? has that gone too? Drew had a strange vibration which took a couple of years to sort , it was his fancy chrome wheel nuts... throwing the wheel balance out .he even had the Driveshaft rebalanced twice. :laughing6:

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Jeremy
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Re: Engine squealing?

Post by Jeremy » Sun 30 Jul, 2017 9:07 pm

Haven't had a chance to test the vibration out yet but my suspicion is that that problem is elsewhere. No fancy wheel nuts but maybe I should try removing my hubcaps and trim rings and see if that has any effect.
1965 220Sb

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