 Noisy Alternator Belt, FIXED! |
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| michael7810 |
 Dec 10 2016, 06:57 PM
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#1
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Senior Member  Group: Members Posts: 1,082 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region 
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My alternator belt is really noisy...it's hard to describe. Not a squeal like a loose AC belt it's more like a squeakey knocky sound. It's been getting worse for a few months...it used to go away once the engine warmed up but now it bad all the time. The belt has about 15k miles and the tension feels about right - a little play between both pulleys. I have not tried to adjust it yet. Can't remember the brand of the belt but it has a ribbed surface (i.e. not smooth belt against the pulleys). Out of desperation and because I had a can in the garage, I sprayed it with CRC Belt Conditioner and holy crap the noise got much louder (same weird noise just louder). Any recommendations for quieting it down short of replacing the belt?
TIA, Mike |
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| mark04usa |
Dec 10 2016, 08:12 PM
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#2
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'70 1.7 Tangerine Group: Members Posts: 351 Joined: 14-September 09 From: Austin TX Member No.: 10,805 Region Association: Southwest Region
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Check alternator mounting and bearings, since you're hearing unusual noises.
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| '73-914kid |
Dec 10 2016, 09:16 PM
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#3
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Senior Member Group: Members Posts: 1,473 Joined: 1-November 08 From: Vista, CA Member No.: 9,714 Region Association: Southern California  |
What brand is the belt?
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| michael7810 |
Dec 11 2016, 07:28 AM
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#4
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Senior Member Group: Members Posts: 1,082 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region
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I don't remember the brand of belt. It's been on since I rebuilt the motor 6 years ago. If I do get a replacement, is there a recommendation?
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| '73-914kid |
Dec 11 2016, 09:37 AM
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#5
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Senior Member Group: Members Posts: 1,473 Joined: 1-November 08 From: Vista, CA Member No.: 9,714 Region Association: Southern California |
I've had good luck with both Gates XL belt you can buy from Oreilly's, as well as the Contitech belt.
BTW, back when I used to Daily Drive a 4 cylinder, the longest time I could get on a belt before it started cracking, and the belt surface polished itself (which causes the squeeking) was maybe 2 years.. |
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| rhodyguy |
Dec 11 2016, 10:13 AM
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#6
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,188 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
Loosen the belt tension and see if the alt moves around. I chased a squeek/rattle for a long time. It was a loose bracket. I couldn't maintain the proper belt tension either. The 2 nuts that retain the bracket to the case were a real hassle to access. Steve pratel went thru a number of brackets on his 912E. A current thread of his shows what's involved when dealing with the bracket.
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| Kansas 914 |
Dec 11 2016, 10:34 AM
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#7
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
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QUOTE('73-914kid @ Dec 11 2016, 08:37 AM)  BTW, back when I used to Daily Drive a 4 cylinder, the longest time I could get on a belt before it started cracking, and the belt surface polished itself (which causes the squeeking) was maybe 2 years.. I have your old 4 cylinder engine out while the car is being repainted and although the belt looked great I replaced it with a Gates belt. (IMG:style_emoticons/default/beer.gif) I threw the original belt in my emergency spares kit. |
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| michael7810 |
Dec 11 2016, 06:21 PM
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#8
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Senior Member Group: Members Posts: 1,082 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region
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Thanks. I'll try a new belt and check the brackets bearings etc while I have it opened up. I'm currently dealing with a plugged Weber idle circuit on #3 that feel like theres a chunk of rubber in the idle jet hole. It's definitely not the o ring but when I try to install the jet something squishy in the hole keeps pushing it out. I can remove the jet and the mixture screw while running and it makes no difference. #3 CHT doesn't move when I start the engine. I tried carb cleaner but no luck. Looks like it's carb rebuild time.
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| Elliot Cannon |
Dec 11 2016, 11:01 PM
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#9
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914 Guru Group: Retired Members Posts: 8,487 Joined: 29-December 06 From: Paso Robles Ca. (Central coast) Member No.: 7,407 Region Association: None
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QUOTE(michael7810 @ Dec 11 2016, 04:21 PM) Thanks. I'll try a new belt and check the brackets bearings etc while I have it opened up. I'm currently dealing with a plugged Weber idle circuit on #3 that feel like theres a chunk of rubber in the idle jet hole. It's definitely not the o ring but when I try to install the jet something squishy in the hole keeps pushing it out. I can remove the jet and the mixture screw while running and it makes no difference. #3 CHT doesn't move when I start the engine. I tried carb cleaner but no luck. Looks like it's carb rebuild time. Use an inspection mirror and a flashlight to look inside where the idle jet goes and see if you can see an obstruction. If you remove the idle jet and hold it up to the light, look at it with a magnifying glass (it's a very small hole) to see if you can see through the hole. If it is blocked, use compressed air to clear it. If that doesn't work, use a small strand of copper wire to clear what ever is in there. But then again, it might just be carb re-build time. (IMG:style_emoticons/default/biggrin.gif) If you re-build the carbs, make sure you use one or more good fuel filters. |
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| michael7810 |
Dec 12 2016, 07:22 AM
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#10
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Senior Member Group: Members Posts: 1,082 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region
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There's something jammed in there that I can't remove with on the car. Time for a rebuild and install Jet Doctor to reduce idle jet clogging issues
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| michael7810 |
Jan 5 2017, 03:04 PM
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#11
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Senior Member Group: Members Posts: 1,082 Joined: 6-June 11 From: Scottsdale, AZ Member No.: 13,164 Region Association: Southwest Region
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Got it running again after rebuilding the carbs. My neighbor was helping me adjust them and was certain the belt noise was an alternator bearing. Given he's a retired machinist (the old fashioned type before CNC) and pretty good diagnosing noises I decided it was time to get to the bottom of it. I removed the belt and it looked glazed but the alternator mounts were tight and the bearings felt perfect. So Bob, who can fix damn near anything that doesn't have a computer attached, asked for some sandpaper and went to work removing the glaze. While he was doing that I cleaned the sticky belt conditioner from the fan and alternator grooves. That completely fixed the problem. I'll order a spare belt but for now I'm driving the hell out of it before it gets hot in Phoenix.
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| rgalla9146 |
Jan 5 2017, 04:35 PM
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#12
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Advanced Member Group: Members Posts: 4,624 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None
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Not long ago a 914 friend came by with an unusual slapping/ knocking noise.
It turned out to be an alternator belt with a large piece flapping loose from it's outer surface. Cut the flap off to confirm then replaced the belt. |
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