Request assistance identifying likely culprit [message #250211] |
Tue, 20 May 2014 18:04 |
verg
Messages: 54 Registered: September 2006 Location: Gettysburg, PA
Karma: 0
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Dear Friends,
Having driven our "new" GMC very little since it came home (about 2 months ago), I felt it was time to take it on a short trip preparatory to taking it any distance. During the last few weekly start ups, I noticed an increasing "belt" sound. Today, I set aside some time to go down and tighten what I assumed was the alternator belt - as putting a load on the alternator seemed to exacerbate the noise. Sure enough, the belt was somewhat loose - perhaps deflecting 2 inches.
I figured out how to undo the alternator and with my son pulling on a large lever, we tightened the alternator so it deflects about 1/2 inch, perhaps a hair more.
Start up and VERY loud noise. Shut things down quickly. The Alternator belt is warm, the AC belt is HOT. Dash heater/AC controls were set to "defrost" then
"off."
Took out the magic elf box (smart phone) and video recorded another start up. (Happy how it starts right up) Would you experienced souls take a look and listen? I don't think its the alternator belt as the sound seems to be coming from the passenger side. My son went outside of the coach and confirmed that from the outside front it sounded like the passenger side.
The dash AC does hot work (coach has 3 roof top units) and the air intake under the "hood" is blocked off to stop drafts I suppose.
Video here
Thank you very much for your time and consideration,
John
John Novicki
near Gettysburg, Pa
Looking for Glenbrook Yellow Plaid Material
'75 Glenbrook 26' "Bumble"
'86 300SL
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Re: Request assistance identifying likely culprit [message #250213 is a reply to message #250211] |
Tue, 20 May 2014 18:22 |
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wally
Messages: 643 Registered: August 2004 Location: Omaha Nebraska
Karma: 5
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Senior Member |
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verg wrote on Tue, 20 May 2014 18:04Dear Friends,
Having driven our "new" GMC very little since it came home (about 2 months ago), I felt it was time to take it on a short trip preparatory to taking it any distance. During the last few weekly start ups, I noticed an increasing "belt" sound. Today, I set aside some time to go down and tighten what I assumed was the alternator belt - as putting a load on the alternator seemed to exacerbate the noise. Sure enough, the belt was somewhat loose - perhaps deflecting 2 inches.
I figured out how to undo the alternator and with my son pulling on a large lever, we tightened the alternator so it deflects about 1/2 inch, perhaps a hair more.
Start up and VERY loud noise. Shut things down quickly. The Alternator belt is warm, the AC belt is HOT. Dash heater/AC controls were set to "defrost" then
"off."
Took out the magic elf box (smart phone) and video recorded another start up. (Happy how it starts right up) Would you experienced souls take a look and listen? I don't think its the alternator belt as the sound seems to be coming from the passenger side. My son went outside of the coach and confirmed that from the outside front it sounded like the passenger side.
The dash AC does hot work (coach has 3 roof top units) and the air intake under the "hood" is blocked off to stop drafts I suppose.
Video here
Thank you very much for your time and consideration,
John
John. AC belt being HOT makes me think the compressor is locked or the clutch bearing is shot causing AC belt slip. You might try starting without the compressor engaged or take that belt off. That upholstery looks familiar!
Wally Anderson
Omaha NE
75 Glenbrook
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Re: [GMCnet] Request assistance identifying likely culprit [message #250214 is a reply to message #250211] |
Tue, 20 May 2014 18:23 |
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USAussie
Messages: 15912 Registered: July 2007 Location: Sydney, Australia
Karma: 6
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Senior Member |
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John,
Remove the air cleaner and get a BRIGHT light and hold it above the front of the engine so we can see what the fan is doing. It
sounds like the fan is scraping on something.
Regards,
Rob M.
-----Original Message-----
From: John Novicki
Dear Friends,
Having driven our "new" GMC very little since it came home (about 2 months ago), I felt it was time to take it on a short trip
preparatory to taking it any distance. During the last few weekly start ups, I noticed an increasing "belt" sound. Today, I set
aside some time to go down and tighten what I assumed was the alternator belt - as putting a load on the alternator seemed to
exacerbate the noise. Sure enough, the belt was somewhat loose - perhaps deflecting 2 inches.
I figured out how to undo the alternator and with my son pulling on a large lever, we tightened the alternator so it deflects about
1/2 inch, perhaps a hair more.
Start up and VERY loud noise. Shut things down quickly. The Alternator belt is warm, the AC belt is HOT. Dash heater/AC controls
were set to "defrost" then "off."
Took out the magic elf box (smart phone) and video recorded another start up. (Happy how it starts right up) Would you experienced
souls take a look and listen? I don't think its the alternator belt as the sound seems to be coming from the passenger side. My
son went outside of the coach and confirmed that from the outside front it sounded like the passenger side.
The dash AC does hot work (coach has 3 roof top units) and the air intake under the "hood" is blocked off to stop drafts I suppose.
Video http://www.replications.com/gmc/20140520.mp4
Thank you very much for your time and consideration,
John
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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Re: [GMCnet] Request assistance identifying likely culprit [message #250229 is a reply to message #250214] |
Tue, 20 May 2014 20:07 |
A Hamilto
Messages: 4508 Registered: April 2011
Karma: 39
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Senior Member |
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USAussie wrote on Tue, 20 May 2014 18:23John,
Remove the air cleaner and get a BRIGHT light and hold it above the front of the engine so we can see what the fan is doing. It
sounds like the fan is scraping on something.
Regards,
Rob M. If that's the cause, maybe the water pump bearing is shot. I have seen them wobble pretty bad before they start to leak.
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