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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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 Posted: Thu Jun 24, 2021 3:47 pm Post subject: Engine making weird screeching noise |
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Hello all!
So, I've installed a new engine in my bus (Old engine blew up, rod bearing spun, cheap rebuild, long story!) and it's making a very weird noise, almost like a screech. I've uploaded a small snip to Youtube and I'll link it here (Please ignore the high revving at idle, I'm not quite sure why it's doing that but I think I just need to fine tune the timing, mixture, fuel pressure, and all that)
https://youtu.be/5hvk7gslyCE
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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cmonSTART
Samba Member
Joined: July 15, 2014
Posts: 1915
Location: NH
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| Posted: Thu Jun 24, 2021 3:52 pm Post subject: Re: Engine making weird screeching noise |
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Link
Alternator whine? Does it make the same noise with the alternator belt off?
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'78 Bus 2.0FI
de K1IGS |
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Cap10323
Samba Member
Joined: July 24, 2016
Posts: 604
Location: Ohio
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| Posted: Thu Jun 24, 2021 5:18 pm Post subject: Re: Engine making weird screeching noise |
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Try running it with the alternator disconnected.
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-Ian
'77 Westfalia - 2.0 F.I |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Thu Jun 24, 2021 5:20 pm Post subject: Re: Engine making weird screeching noise |
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| cmonSTART wrote: |
Link
Alternator whine? Does it make the same noise with the alternator belt off? |
\
It could be, but I've noticed, as I've failed to dial in a proper idle, if the engine lowers in rpm and then dies, the sound goes away. So, it's very noticeable at high RPM. Dunno if that singles out alternator or not
I've noticed though the sound seems to come from the left of the engine. When I leaned over the engine lid opening while it was making that sound, I swear it was coming from the left side (It could very well be an echo, but just thought I should mention it)
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Thu Jun 24, 2021 7:29 pm Post subject: Re: Engine making weird screeching noise |
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I watched it four times. That sounds like an alternator. And...you have way too much belt motion going on. Check belt tension. Also check sheet metal around alternator and fan for contact to moving parts.
Ray |
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aeromech
Samba Member
Joined: January 24, 2006
Posts: 16954
Location: San Diego, California
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| Posted: Thu Jun 24, 2021 7:54 pm Post subject: Re: Engine making weird screeching noise |
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I had an engine once make a noise like that. Turned out to be a dry cam lobe riding on the points block in the distributor. Just a touch of grease on the distributor cam solved it
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Lead Mechanic: San Diego Air and Space Museum
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Cap10323
Samba Member
Joined: July 24, 2016
Posts: 604
Location: Ohio
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| Posted: Thu Jun 24, 2021 9:20 pm Post subject: Re: Engine making weird screeching noise |
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| raygreenwood wrote: |
I watched it four times. That sounds like an alternator. And...you have way too much belt motion going on. Check belt tension. Also check sheet metal around alternator and fan for contact to moving parts.
Ray |
I just noticed that, your belt is loose as a goose. You may just be hearing the belt slipping on the alternator pulley.
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-Ian
'77 Westfalia - 2.0 F.I |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Fri Jun 25, 2021 7:20 am Post subject: Re: Engine making weird screeching noise |
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I took the pulley belt off and the sound didn't go away
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Fri Jun 25, 2021 7:21 am Post subject: Re: Engine making weird screeching noise |
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| aeromech wrote: |
| I had an engine once make a noise like that. Turned out to be a dry cam lobe riding on the points block in the distributor. Just a touch of grease on the distributor cam solved it |
Do you mean the square cam that actuates the points inside the cap?
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21507
Location: Oklahoma City
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| Posted: Fri Jun 25, 2021 7:55 am Post subject: Re: Engine making weird screeching noise |
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| P24p1 wrote: |
| I took the pulley belt off and the sound didn't go away |
Good diagnostics.....continue on......check very carefully for sheet metal movement and vibration.
Also.....from looking at your video.....you have an exhaust leak that appears to drive an occasional misfire. Everytime this misfire manifests itself.....you can see the belt nump slightly in the video.
Watch for it.....calibrate your eyes and ears together...faint tap or pop and belt appears to almost stop for a thousandth of a second and then wobbles.
This sound you are hearing.....you describe as a "screech".....i don't hear as a screech at all. To me......its more similar to the metallic popping sound you hear from the peashooter exhausts from a beetle engine.
Going off memory.....I have had this sound on my type 4 engines.... from a leaking muffler to heat exchanger gasket.....and from an internal crack in the paired exhaust pipe just inside of the muffler body.....heat erosion, vibration and age caused that. I could not find it witjout taking the muffler loose and visyally inspecting.
But ai was able to find the leaking HE to muffler gasket by putting soapy,water on it,when cold and then starting the engine to see it foam.
I also at one point had a softer version of this sound....at least in my memory.... created by a leaking tailpipe to muffler gasket......and.....from a bent or loose pushrod retainer wire working against a pushrod
It very well could be a points cam issue as mentioned......but that sound created by the points cam....to me....IS a screech.
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Wildthings
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Joined: March 13, 2005
Posts: 50331
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| Posted: Fri Jun 25, 2021 8:01 am Post subject: Re: Engine making weird screeching noise |
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| There is a spacer washer that goes behind the engine cooling fan, pull the fan and make sure it is there. |
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aeromech
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Joined: January 24, 2006
Posts: 16954
Location: San Diego, California
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| Posted: Fri Jun 25, 2021 9:19 am Post subject: Re: Engine making weird screeching noise |
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| P24p1 wrote: |
| aeromech wrote: |
| I had an engine once make a noise like that. Turned out to be a dry cam lobe riding on the points block in the distributor. Just a touch of grease on the distributor cam solved it |
Do you mean the square cam that actuates the points inside the cap? |
Yes, there needs to be a very slight film of grease on the part of the cam that hits the point rub block
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50331
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| Posted: Fri Jun 25, 2021 9:37 am Post subject: Re: Engine making weird screeching noise |
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| aeromech wrote: |
| P24p1 wrote: |
| aeromech wrote: |
| I had an engine once make a noise like that. Turned out to be a dry cam lobe riding on the points block in the distributor. Just a touch of grease on the distributor cam solved it |
Do you mean the square cam that actuates the points inside the cap? |
Yes, there needs to be a very slight film of grease on the part of the cam that hits the point rub block |
There are special distributor cam greases sold for this purpose but any grease is better than none. Your contact point life will be very short if grease isn't used verses 20K miles or so if it is used. I usually re-smear the grease at about 10K miles and replace it at 20K miles when I pull the points and file them back flat and then run them for another 20K. I am presently running Echlin ventilated points from NAPA which give me excellent service, best not to run Bosch as their quality has gone to crap and can leave you stranded. If you live in a really dusty place regreasing the distributor cam at shorter intervals may be called for. |
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aeromech
Samba Member
Joined: January 24, 2006
Posts: 16954
Location: San Diego, California
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| Posted: Fri Jun 25, 2021 9:50 am Post subject: Re: Engine making weird screeching noise |
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I was about 18. I had washed the distributor clean with gasoline and ran it without any lube at all. Created a screech
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Fri Jun 25, 2021 10:55 am Post subject: Re: Engine making weird screeching noise |
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Tried the grease, didn't work 
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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timvw7476
Samba Member
Joined: June 03, 2013
Posts: 2196
Location: seattle
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| Posted: Fri Jun 25, 2021 11:16 am Post subject: Re: Engine making weird screeching noise |
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it will be more obvious what it is when the engine turns lower than 2,400rpm.
But the big fan washer check is the first place to check, as mentioned above... |
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cellobus1
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Joined: June 10, 2014
Posts: 284
Location: East Tennessee
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| Posted: Fri Jun 25, 2021 1:31 pm Post subject: Re: Engine making weird screeching noise |
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Just jumping in to say look for something under the fan pulley; a 10 mm socket, a bolt, even an acorn can make this noise rubbing on the pulley and they are hard to see in there unless you know there's a gap.
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1976 unrestored daily driver Standard bus, "Stella"
formerly, 1959 Standard bus
formerly, 1973 transporter which was 4 years old when it taught me to drive |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Fri Jun 25, 2021 1:48 pm Post subject: Re: Engine making weird screeching noise |
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Well, it seems like removing the fan is the first point of business. I will do that and report back
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1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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P24p1
Samba Member
Joined: August 20, 2020
Posts: 363
Location: Canada, Quebec
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| Posted: Sat Jun 26, 2021 5:08 pm Post subject: Re: Engine making weird screeching noise |
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Alrighty, fixed!
Not only fixed, but double fixed! Turns out the sound you can hear is just a massive vacuum leak! I replaced the gaskets on the intake manifolds just to see what would happen and now the engine idles nicely and the sound is gone.
Hopefully this can help someone in future
_________________
1973 Westfalia named Angie
What rust?
Rev it - don't lug it! |
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cmonSTART
Samba Member
Joined: July 15, 2014
Posts: 1915
Location: NH
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| Posted: Sat Jun 26, 2021 5:29 pm Post subject: Re: Engine making weird screeching noise |
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Nice!!
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'78 Bus 2.0FI
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