another new noise

[starrider1946]

I had posted about a vibration issue and I think I solved it. Saturday I pulled my pipes off ( to repaint them and get them out of the way to adjust my valves). I took the nut off that holds the fan on and checked around where the fan bolts up with my inspection mirror to check for cracks in the fan but it look fine. I put the nut back on and torqued it to 40 ft lbs. I put everything back together and still had the vibration and picked up another rattling type noise that I didn't have. I found out ( I think) the vibration noise starting around 1700 rpm was the alternator strap wasn't tight enough. I actually broke the one on it tightening it up because I didn't think it was tight enough. I put a used one on it tightened it up good and the vibration seems to be gone but I have a rattling or jingling type sound coming for the alternator, fan pulley area. I reached inside the fan shroud and felt the fan and it seems tight. When it is running I can see the fan and it looks like it is running true. I know I need a new alternator pulley and I have one coming. I can't get the adjustment right on the belt. It is tight then loose when rolling the motor over by hand.
I took the belt off started it up and the noise is gone. Could the pulley be making the alternator make a noise. It is a fairly new alternator. I don't feel any bearing slack in either end. I am going to put my new pulley and belt on when it gets here and see if that helps. What gets me is it wasn't making this noise before. I may pull the fan nut off again and make sure I have everything right. I can't believe the fan would have just broke or the alternator went bad. Any suggestions. Thanks

 

[Sidecarbill]

You are putting the shim washers between the pulley halves correct? The amount of washers never changes just their position.

 

[starrider1946]

Yeah I am running a total of 10 shims. Right now I have three between the two halves that amount to about .085 thousandths. The rest are on the outside.I am running a 11.3 x 912 belt which I believe you run with a alternator. I wish my new pulley would get here so I can try that. There has to be something wrong with my pulley for the belt to be loose and tight.

You are putting the shim washers between the pulley halves correct? The amount of washers never changes just their position.

 

[stinger608]

Maybe the pulley is bent or something. Probably good that you ordered a new one.

When you pulled the fan, did you by chance check the dividers inside the dog house? I remember years ago, a customer came in with a rattle and we chased it for a couple of days before finding one of the dividers inside the dog house had let go.

They, as I recall, are just spot welded to the outer walls of the dog house. Seems like there are 2 of them inside the dog house.

 

[starrider1946]

new noise

I didn't check anything in the doghouse. I just loosened the nut, took it off and looked where the fan fits on the fan adapter for the alternator to see if if was cracked. I didn't see anything so I put the nut back on and torqued it to 40 ft. lbs. I may just take the alternator and fan out so I can see in the doghouse and see if I see anything it this new pulley doesn't fix my problem. I have a aftermarket chrome type doghouse. Will it have dividers in it also? It does sound like it could be something loose. Kind of like putting some washers in a tin can and rattling it if that makes sense. Running me crazy but I am going to find it. Thanks for the suggestions.

Maybe the pulley is bent or something. Probably good that you ordered a new one.

When you pulled the fan, did you by chance check the dividers inside the dog house? I remember years ago, a customer came in with a rattle and we chased it for a couple of days before finding one of the dividers inside the dog house had let go.

They, as I recall, are just spot welded to the outer walls of the dog house. Seems like there are 2 of them inside the dog house.

 

[stinger608]

Yep, all the dog houses have the dividers. They direct air flow down toward the cylinder heads.

Being one of the aftermarket chrome types, I could see one of em breaking loose. That would for sure cause such a sound. A lot of them are very cheaply made.

The air would push a broken one away and it would bounce back and forth making a "washers in a tin can" sound.

 

[rodekyll]

when I worked for VW we had a bug come in with a horrible vibration. the problem went away when I disconnected the fan belt. I reached around and felt inside the fan. There was a wad of -- yes -- centrifuged squirrel in the squirrel cage fan. I didn't clean it out.

If the belt goes tight and loose per revolution, a pulley shiv is not centered. Find out if your loose/tight follows the crank or alternator shiv. That will be the troublemaker.

Also, the alt pulley may have a wide and narrow slot to mate up the halves. If you're mis-indexed, that will take the shiv center away from the pulley center. Having a shim slip during pulley assembly will do the same thing.

You really do not need or want a 'tight' belt to the alternator. You should be able to deflect the belt about 3/8" when it's set up properly.

My WAG is that either the fan is badly out of balance/bent/missing a fin or at some point the belt was overtightened against an off-centered shiv and has compromised the alternator bearings by excessively sideloading them.

$0.02

 

[starrider1946]

noise

The divider thing could be it. My luck would be something like that. Can I tell if I pull the alternator and fan out? and look and feel inside the dog house to feel for any loose parts. I'll check the shims and make sure they are centered rodekyll, what do you mean by a pulley shiv not centered? And if the loose tight follows the crank or alternator shiv. Without the belt on the alternator feels good . No play in either end up and down. I'll keep posting. Thanks

when I worked for VW we had a bug come in with a horrible vibration. the problem went away when I disconnected the fan belt. I reached around and felt inside the fan. There was a wad of -- yes -- centrifuged squirrel in the squirrel cage fan. I didn't clean it out.

If the belt goes tight and loose per revolution, a pulley shiv is not centered. Find out if your loose/tight follows the crank or alternator shiv. That will be the troublemaker.

Also, the alt pulley may have a wide and narrow slot to mate up the halves. If you're mis-indexed, that will take the shiv center away from the pulley center. Having a shim slip during pulley assembly will do the same thing.

You really do not need or want a 'tight' belt to the alternator. You should be able to deflect the belt about 3/8" when it's set up properly.

My WAG is that either the fan is badly out of balance/bent/missing a fin or at some point the belt was overtightened against an off-centered shiv and has compromised the alternator bearings by excessively sideloading them.

$0.02

 

[rodekyll]

I mean that the pulley halves (shivs) are not spinning on the same center and in the same plane as the alternator shaft. The most common reason is that the two shivs (pulley halves) are misaligned -- either the big tab/little tab in the wrong holes, a shim slipped keeping the shivs from mating, one shive is warped, the alternator shaft is bent, or that 'bell' washer that goes directly behind the pulley nut slipped. Any of the above will result in the belt running deeper (looser) at one point of rotation and higher (tighter) at some other point. Of course that's going to ruin the rotational balance and cause a harmonic vibration. It can also get the fan thrashing and scraping on the edges of doghouse stuff.

This can happen with the alternator otherwise feeling 'normal' when the belt is removed, since it's the relationship of the belt to the pulleys that's the problem in my WAG scenario. The trick is to watch the pulleys go 'round at low (starter) speeds (belt installed) to see if you can eyeball the wobble. Once you can see it you can kill it.

Yes, you can get you hand in the big doghouse hole if you get the alternator and flange out. Depending on what-all you've got going on back there equipment-wise that could be much easier said than done. The doghouse might need to be unbolted and lifted to clear the alternator pedestal. If you have the heat flaps installed you have to pull the thermostats bellows and linkage to lift the shroud. The throttle cable can get bound and kinked whenever you tinker with the shroud. So be careful with it! Different carb/injection setups can make removing the intake and other things necessary, too. So I wouldn't pull the alternator until I was convinced that I had to. Checking the pulley stuff has a high enough percentage that I'd try that first.

Another way to check for loose baffles is to tap the doghouse here and there and listen for the loose panel to reveal itself. Quite often you can hear or feel the troublemaker flap as you tap.

That's all I've got right now. I'm working on a superbeetle right now. Engine is out and (oem) fan shroud is removed. If you need me to look at anything in the unseeable behinds of the engine, let me know. It goes back together thurs/fri.

 

[starrider1946]

Thanks rodekyll. I have one of the aftermarket pulleys. I went and checked it awhile ago. The way it is made it will only go on one way. The outside pulley is rounded on one part of the hole and flat on the other end. I wish I could find an original type pulley.
I didn't think to just check it with the coil wire pulled and just let it turn over and see if I can tell anything. I will do that tomorrow. I can see on the alternator where the pulley has scraped it but I don't know when. I am not going to do anything until I get the new pulley on and hope that fixes it. I hope it comes in tomorrow. As soon as I put on I'll repost with the results. Thanks for the help.

I mean that the pulley halves (shivs) are not spinning on the same center and in the same plane as the alternator shaft. The most common reason is that the two shivs (pulley halves) are misaligned -- either the big tab/little tab in the wrong holes, a shim slipped keeping the shivs from mating, one shive is warped, the alternator shaft is bent, or that 'bell' washer that goes directly behind the pulley nut slipped. Any of the above will result in the belt running deeper (looser) at one point of rotation and higher (tighter) at some other point. Of course that's going to ruin the rotational balance and cause a harmonic vibration. It can also get the fan thrashing and scraping on the edges of doghouse stuff.

This can happen with the alternator otherwise feeling 'normal' when the belt is removed, since it's the relationship of the belt to the pulleys that's the problem in my WAG scenario. The trick is to watch the pulleys go 'round at low (starter) speeds (belt installed) to see if you can eyeball the wobble. Once you can see it you can kill it.

Yes, you can get you hand in the big doghouse hole if you get the alternator and flange out. Depending on what-all you've got going on back there equipment-wise that could be much easier said than done. The doghouse might need to be unbolted and lifted to clear the alternator pedestal. If you have the heat flaps installed you have to pull the thermostats bellows and linkage to lift the shroud. The throttle cable can get bound and kinked whenever you tinker with the shroud. So be careful with it! Different carb/injection setups can make removing the intake and other things necessary, too. So I wouldn't pull the alternator until I was convinced that I had to. Checking the pulley stuff has a high enough percentage that I'd try that first.

Another way to check for loose baffles is to tap the doghouse here and there and listen for the loose panel to reveal itself. Quite often you can hear or feel the troublemaker flap as you tap.

That's all I've got right now. I'm working on a superbeetle right now. Engine is out and (oem) fan shroud is removed. If you need me to look at anything in the unseeable behinds of the engine, let me know. It goes back together thurs/fri.

 

[starrider1946]

I think I found out what my noise was. Fan was cracked. I don't believe I had the alternator strap tight and it let everything vibrate. I put on a new fan, alternator pulley and new belt. Going to road test it tomorrow. I have another question and I am going to post it under (cylinders 2 & 4 running lean) Thanks for all the help.

 

[stinger608]

I think I found out what my noise was. Fan was cracked

Oh, hell yea!! That will do it, man. Every time. LOL