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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Mon Oct 03, 2022 8:44 pm Post subject: Unusual noise - please help diagnose |
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My 1961 beetle has begun making a loud unusual noise.
It appears to be coming from the generator although it could also be coming from the fan. Frankly I really can't tell where the noise is coming from.
I thought it might be the tappets but they all seem good at c.0.005-0.006".
I recently changed the fanbelt. I thought it might be the generator bearings although I doubt it would make the 'click-click' noise I'm hearing.
I can detect no difference in the running of the car.
The noise disappears when the engine warms up. After twenty minutes driving, with the engine at idle, I can detect no discernible noise.
This has me perplexed and worried. It is my daily driver. It started making the noise yesterday and continues to make the noise every time I start the car.
Here is a video of the engine running:
Link
And here is a video of fanbelt tension:
Link
https://youtube.com/shorts/gxsYzjFDC18?feature=share
Please help me diagnose. _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5481 Location: Seattle
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Posted: Mon Oct 03, 2022 8:55 pm Post subject: Re: Unusual noise - please help diagnose |
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Since it is a cold only problem give it a brief cold start without a fan belt. Shut the engine back down pretty quickly but you should be able to tell in 30 seconds if the noise goes away. The goal here is to split the problem in half. Fan belt up or the engine itself.
I couldn't hear it too clearly in the video. For a bit it sounded like and exhaust leak in 1 cylinder but then not so much. I'm wondering about a loose flywheel. Last time I hear that it was a kinda double click (cl-la, cl-la, cl-la) and most noticeable at idle. Mine didn't go away after warming up though. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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mukluk Samba Member
Joined: October 18, 2012 Posts: 7028 Location: Clyde, TX
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Posted: Mon Oct 03, 2022 9:10 pm Post subject: Re: Unusual noise - please help diagnose |
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It almost sounds like the voltage regulator body is rattling or maybe the contacts inside chattering.
I'd agree with EVfun, do a cold start with the belt removed to see if the noise is still present or disappears with the generator and fan not spinning. _________________ 1960 Ragtop w/Semaphores "Inga" |
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67rustavenger Samba Member
Joined: February 24, 2015 Posts: 9769 Location: Oregon
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Posted: Mon Oct 03, 2022 9:46 pm Post subject: Re: Unusual noise - please help diagnose |
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mukluk wrote: |
It almost sounds like the voltage regulator body is rattling or maybe the contacts inside chattering.
I'd agree with EVfun, do a cold start with the belt removed to see if the noise is still present or disappears with the generator and fan not spinning. |
Either the fan is scrapping inside the fan shroud.
Or the crank pulley is scrapping on the tin forward of the pulley, it happens!
Take the fan belt off and run the engine for a brief time to see it the sound goes away. _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Mon Oct 03, 2022 9:56 pm Post subject: Re: Unusual noise - please help diagnose |
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Ok thanks good thinking. I'll take the fanbelt off and give it a whirl. I'll report back once done, probably six hours or so. _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24764 Location: Olympia Wash Rinse & Repeat
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Posted: Tue Oct 04, 2022 9:10 am Post subject: Re: Unusual noise - please help diagnose |
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Wonder if some welds inside the muffler have given away. Then when really hot it expands and quiets down. _________________ In Stereo, Where Available! |
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MrGoodtunes Samba Member
Joined: May 14, 2012 Posts: 852 Location: South Florida
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Posted: Tue Oct 04, 2022 12:25 pm Post subject: Re: Unusual noise - please help diagnose |
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If test #1 (run without fan belt) gets rid of the noise, then test #2 might be:
• Re-install fan belt & start engine (expect noise returns)
• Grab upper left and right of fan shroud with both hands
• Push, pull, and twist the shroud, does noise change? |
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rcooled Samba Member
Joined: September 20, 2008 Posts: 2506 Location: Santa Cruz, CA
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Posted: Tue Oct 04, 2022 6:21 pm Post subject: Re: Unusual noise - please help diagnose |
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tomfreo wrote: |
I thought it might be the tappets...might be the generator bearings |
That noise isn't coming from the valves or the generator bearings.
Did it start suddenly...like right after you changed the belt, or has it gradually gotten louder or more noticeable over time?
Eric&Barb wrote: |
Wonder if some welds inside the muffler have given away. |
I've had this happen. Also check the perforated inserts inside the tailpipes. They can rust out and start rattling around.
A mechanic's stethoscope can be a big help in locating the source of odd noises like this. Available from Amazon: https://www.amazon.com/Mechanics-Stethoscope-Diagn...3924831423 _________________ '63 Ragtop (current)
'65 Ghia coupe (totaled)
'67 Ghia convertible (current)
'69.5 Ghia convertible and
'62, '63, '65, '69 Bugs (all long gone) |
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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Wed Oct 05, 2022 5:32 pm Post subject: Re: Unusual noise - please help diagnose |
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I took the fanbelt off and the noise stopped. Put the belt back on and tried pushing and pulling on fan shroud. No change in noise.
Some notes. If I increase engine revs the noise fades away. The noise also disappears after only ten minutes of running (maybe sooner but that's how long it took me to run down to the shops yesterday).
Here's another video. In it I vary the revs. You can hear the noise going away and coming back. Although I got to say, the audio in the video is not as obvious as when you're standing behind the engine.
Link
I did fashion a 'stethoscope' from a piece of tubing but couldn't locate the sound.
Quote: |
Did it start suddenly...like right after you changed the belt, or has it gradually gotten louder or more noticeable over time? |
It did start suddenly - one morning the noise was there and obvious. (Having said that, I'm starting to wonder whether I wasn't hearing something a little suspicious over winter, something slightly similar. Certainly, it suddenly got very loud and obvious.)
The new fanbelt's been on for a few weeks now.
Quote: |
Or the crank pulley is scrapping on the tin forward of the pulley, it happens! |
Noise gone with belt off - can only be generator or fan right?
Quote: |
It almost sounds like the voltage regulator body is rattling or maybe the contacts inside chattering. |
The voltage reg is solid on the generator. The noise is kinda deep and I don't think it could be contacts chattering.
Any other suggestions? _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5481 Location: Seattle
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Posted: Wed Oct 05, 2022 6:06 pm Post subject: Re: Unusual noise - please help diagnose |
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Move a couple of shims so the fan belt is quite loose and test again. That would suggest generator bearings, and it might be why it suddenly happened when you changed the belt.
I am very happy for you that the sound was not a loose flywheel, it often means the crankshaft and flywheel are garbage and the engine will be getting a full tear down and rebuilt. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Wed Oct 05, 2022 6:33 pm Post subject: Re: Unusual noise - please help diagnose |
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Quote: |
Move a couple of shims so the fan belt is quite loose and test again. That would suggest generator bearings, and it might be why it suddenly happened when you changed the belt. |
The fanbelt is within spec but I've got all shims on the inside. I'm going to have to find more shims to test that one out.
However, the sound is a 'clack-clack-clack' - do bearings make that kind of sound. I would've thought a deep rumble.
Also, it didn't happen suddenly after fanbelt change - maybe 3-4 weeks? Though I guess it is sudden given the car is 60 years old! _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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Bill64 Samba Member
Joined: April 28, 2008 Posts: 17 Location: Ohio
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Posted: Wed Oct 05, 2022 7:20 pm Post subject: Re: Unusual noise - please help diagnose |
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With the fan belt removed, you could check for excessive play in and out and side to side of the armature. Also spin the generator pulley to check for noise, roughness, etc. |
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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Thu Oct 06, 2022 1:29 am Post subject: Re: Unusual noise - please help diagnose |
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Belt off, engine off, spun generator/fan - no noise, nice and smooth. However, reaching behind to fan and pulling seems there's some play.
Link
Found another spare belt. Sizes different!! G'gld Dunlop V559 and got spec of 15.44×36.07". Don't know WTF the first number is but the second presumably is length and comes to 916.18mm. Measured the width of the belt with rule and got 9.5mm.
Replaced this Dunlop belt with the spare (no markings apart from 'Banda' and 'Japan') and noise is gone! Fucking ace.
Sorry for all the drama. However …
I read that fanbelt tension play should be 1.25~2cm. The Dunlop belt had play of 1.25cm. The new 'banda' belt has play of 1.25cm.
Also read that play should be as loose as possible without slipping. Any comments?
Also, please view/listen to video (above) for sound when I reach behind to fan and pull on it. Is this bad?
And this video pulling on generator pulley. Is this bad?
Link
Video spinning generator pulley.
Link
Video belt off.
Link
New 'banda' belt on - noise gone.
Link
I'm aware that audio is not great. Squatting behind beetle with engine runnign the difference in the sound is obvious. In the video, it is not. The video audio of me pulling on fan and generator pulley, however, the sound seems magnified and much louder than I remember.
(And, question is, why do links to 'shorts' youtube vids not render properly?) _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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Bill64 Samba Member
Joined: April 28, 2008 Posts: 17 Location: Ohio
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Posted: Thu Oct 06, 2022 7:45 am Post subject: Re: Unusual noise - please help diagnose |
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I checked the movement on my generator pulley with the belt off. It spins freely with no noticeable in/out movement at all. In your last 10 sec video with the clunking sound, if that is the in/out play, I would say that is excessive. That said, I’m glad your noise went away for now. I would be very suspicious of your generator as the cause of your noise if it returns. The brushes may be intermittently contacting areas on the commutator where they normally wouldn’t contact or the fan may be making slight contact on the shroud with that much movement. If the noise returns, I would also look through the big opening in the generator at the brushes as they contact the armature and see what’s going on as the noise comes and goes. Good luck. |
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VW_Jimbo Samba Member
Joined: May 22, 2016 Posts: 9966 Location: Huntington Beach, CA
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Posted: Thu Oct 06, 2022 8:09 am Post subject: Re: Unusual noise - please help diagnose |
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Get a mirror and have a peak inside, at the front of the fan. Do you see any rusty spots? Powered rusty spots? I am betting the fan has broken at the hub. Not uncommon. _________________ Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
TDCTDI wrote: |
Basically, a whole bunch of fuckery to achieve a look. |
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
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Bill64 Samba Member
Joined: April 28, 2008 Posts: 17 Location: Ohio
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Posted: Thu Oct 06, 2022 8:44 am Post subject: Re: Unusual noise - please help diagnose |
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I agree with your comment “loose as possible without slipping.” |
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carcrazed Samba Member
Joined: November 15, 2007 Posts: 957 Location: Ohio
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Posted: Thu Oct 06, 2022 3:33 pm Post subject: Re: Unusual noise - please help diagnose |
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Sounds like a generator bearing. I would rebuild it or get a new one. _________________ 1965 Herbie Replica. 1776cc dual Kads.
1961 Beetle 33,000 Original Miles
"Just When you think you are getting ahead, you're always wrong." |
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glutamodo The Android
Joined: July 13, 2004 Posts: 26323 Location: Douglas, WY
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Posted: Fri Oct 07, 2022 12:12 pm Post subject: Re: Unusual noise - please help diagnose |
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When I've had odd sounds from that area I'll do a push-pull on the fan shroud at idle and see if the noise changes.
Now one thing that I'm surprised no one has mentioned is to ask if this engine has the original thermostat setup, the big-ass pivoting venturi ring that throttles down the air intake of the engine when cold. If that is out of adjustment it can rub against the fan. However I've only ever seen this sort of ting happen it was with a hot-open thermostat, not cold-closed. _________________ Andy T.
IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox. |
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tomfreo Samba Member
Joined: May 24, 2009 Posts: 373 Location: Western Australia
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Posted: Fri Oct 07, 2022 7:51 pm Post subject: Re: Unusual noise - please help diagnose |
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Thanks for all you guys help. Swapping out the fanbelt has stopped the noise so I'm going to leave it for now.
Quote: |
do a push-pull on the fan shroud at idle |
I did that; no change, shroud firm as.
What I find a little mysterious is: 1) the fanbelt spec was exactly the same between old belt (noise) and new belt (no noise). 2) the noise goes away when the engine warms.
BTW: I've since loosened the belt to 1.5cm / 1".
I think the radial play in generator shaft evidenced by reaching behind fan shroud and pulling on the fan is perhaps not ideal. Maybe it's serious?
I called up the local VW shop to see if they had some generator pulley shims. The first guy I talked to suggested the fan had come loose from shaft (something about a component (?) rounded from square) and described how I might check it. (No problem there). The second guy I spoke to mentioned 'catastrophic' consequences upon hearing the story of the noise fanbelt on and off.
So, obvious radial play but only almost imperceptible axial play and spinning the generator pulley with belt off is smooth with no noise.
On a side note, can anyone interpret the figures for the old ('bad') Dunlop V559? 15.44 x 36.07in. The last figure is 916mm and presumably the length. What's the first figure? _________________ _________________
'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp |
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VW_Jimbo Samba Member
Joined: May 22, 2016 Posts: 9966 Location: Huntington Beach, CA
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Posted: Fri Oct 07, 2022 9:39 pm Post subject: Re: Unusual noise - please help diagnose |
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I believe that the fan is broken. It fractures under the nut and washer. Hard to see, but the tell tail rust trails are always there. The noise is a deep rumble noise with no pattern. Once you tune into it, IT is easily defined.
Pull the 4 6mm bolts, pull the alt strap and remove the assembly. Then remove the cooling fan nut and washer (probably installed wrong) and look for fractures. _________________ Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
TDCTDI wrote: |
Basically, a whole bunch of fuckery to achieve a look. |
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
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