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> alternator belt, keeps flying off
mobymutt
post May 24 2018, 04:30 PM
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Belt flew off last 2 out of 3 drives. I'm assuming it just needs to be tighter, but are there any other potential causes?
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76-914
post May 24 2018, 04:48 PM
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How does it sit in the pulley's. Flush, down or up? 1/2" slack in the belt when squeezed? (IMG:style_emoticons/default/beerchug.gif)
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mobymutt
post May 24 2018, 05:07 PM
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QUOTE(76-914 @ May 24 2018, 06:48 PM) *

How does it sit in the pulley's. Flush, down or up? 1/2" slack in the belt when squeezed? (IMG:style_emoticons/default/beerchug.gif)


I believe it sits down in the pulley.

I had a more experienced friend tighten it the second time, and I think the 1/2" slack when squeezed is what he was going for.

Would it be possible that the alternator seizes when hot?
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Spoke
post May 24 2018, 05:21 PM
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When the belt was off, did you spin the alternator by hand to see if there was binding or bearing sounds?
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iankarr
post May 24 2018, 05:33 PM
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That happened on mine...the pulley turned out to be cracked.
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Rand
post May 24 2018, 05:54 PM
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Pulley alignment causes this. Check all the mounting brackets/bolts first to make sure nothing is loose or broken.
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TheCabinetmaker
post May 24 2018, 06:18 PM
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An old customer bought a 914and drove it for 2 years with no problems. One day it threw the belt and I put a new one on and it came off the next day. The pulley was on backwards and out of align. It took that long to throw it off. I've also seen one with a Ford pulley. As for yours, its probably loose and misaligned
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mobymutt
post May 24 2018, 06:40 PM
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Ok, I do think the pulley might be a bit sloppy, I'll check it out.

I just found my belt on the side of the road, split. So next question, how long can I drive without the alternator charging the battery?
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ConeDodger
post May 24 2018, 06:55 PM
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Alignment is very important. I powder coated all of my engine parts including a washer that acts as a spacer. It kept throwing belts. I left it with McMark and he had to realign the pulleys.
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914Sixer
post May 24 2018, 08:38 PM
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New pulleys over on theSamba.com under 411/412 Parts $40
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Bartlett 914
post May 25 2018, 06:43 AM
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QUOTE(Rand @ May 24 2018, 06:54 PM) *

Pulley alignment causes this. Check all the mounting brackets/bolts first to make sure nothing is loose or broken.

(IMG:style_emoticons/default/agree.gif)
I had this happen to me. The bracket had been loose for some time. It actually damaged the fan housing. The movement of the loose bracket wore the fan housing so when tight, it would not be aligned properly
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iankarr
post May 25 2018, 07:10 AM
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QUOTE(mobymutt @ May 24 2018, 08:40 PM) *

Ok, I do think the pulley might be a bit sloppy, I'll check it out.

I just found my belt on the side of the road, split. So next question, how long can I drive without the alternator charging the battery?

Depends on how fast you’re going, whether you’re turning the engine on and off, and the condition of the battery. Probably not more than an hour of normal driving.

Here’s a pic of my cracked pulley (and the incorrect belt the PO installed)
Attached Image
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rjames
post May 25 2018, 09:27 AM
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How often should the belt be changed? I have no reason to think mine needs replacing other than it's probably been on there for 20 years.
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rhodyguy
post May 25 2018, 10:29 AM
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Contact 914Sixer, Mark, and see if he has anymore of the correctly sized belts. I bought 2 of them. Cheaper than at my FLAPS with shipping included. I figure I'm set for life.
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1adam12
post May 25 2018, 10:39 AM
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Check that alignment like most have already mentioned. Did you happen to recently reinstall your engine tins? Make sure your alternator is not bottoming out on the tin that's on the back side of the cylinder head. I just had this issue when I reinstalled the tins and had to remove and reinstall that piece correctly. Luckily I caught it before starting up the engine.
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mobymutt
post May 25 2018, 11:03 AM
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QUOTE(1adam12 @ May 25 2018, 12:39 PM) *

Check that alignment like most have already mentioned. Did you happen to recently reinstall your engine tins? Make sure your alternator is not bottoming out on the tin that's on the back side of the cylinder head. I just had this issue when I reinstalled the tins and had to remove and reinstall that piece correctly. Luckily I caught it before starting up the engine.


Yeah, I had the whole engine apart last summer...
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914Sixer
post May 25 2018, 01:28 PM
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Yes, I have 5 more correct belts left.
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PanelBilly
post May 25 2018, 02:49 PM
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I had this same problem years ago. It was the pulley that had a small fracture in it. I took it apart several times changing the belt and looking at alignment. When I finely studied the pulley I found the crack.
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mobymutt
post May 25 2018, 07:32 PM
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QUOTE(914Sixer @ May 25 2018, 03:28 PM) *

Yes, I have 5 more correct belts left.


Looks like I'll be needing one. How much?
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mobymutt
post May 25 2018, 07:37 PM
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My pulley actually looks to be in good shape.

As for the alternator, I spun it by hand with the belt off. It spins freely and smoothly, but it does have a squeak. Probably not a good thing.
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