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Posted by: Optimusglen May 15 2019, 11:56 PM

A recent occurrence, I'm getting a pretty loud rattle that sounds like marbles swirling around the bottom of a tin can. Everything else seems fine, power etc. Hear it while in neutral and idling and also while driving in gear. It's drown out by wind noise the faster you go.

Engine is a 1.7 punched up to 1911 on dual Weber 40's. Heat exchangers stripped to bare headers, new muffler. Oil pressure and cylinder head temp both normal.

Posted by: falcor75 May 16 2019, 12:30 AM

Throwout bearing? Does it go away when you depress the clutch?

Posted by: jasons May 16 2019, 06:09 AM

Did something like a loose nut find it's way into your cooling fan?

Posted by: ejm May 16 2019, 07:40 AM

Could be the alternator bearings. Pull the belt and see if the noise goes away.

Posted by: rhodyguy May 16 2019, 08:08 AM

Posted by: Optimusglen May 16 2019, 08:59 AM

I'm leaning alternator bearings... I took this video and uploaded it to Youtube, the noice is certainly coming from that area.

Throw out bearing seems ok, no change when clutch is depressed or released. Also took a look in the fan and all seems well, pulled out a small leaf but that was it.

http://www.youtube.com/watch?v=wvZVJYsfrCU

Posted by: injunmort May 16 2019, 11:02 AM

sounds like fan came loose from hub. try tightening three bolts on the hub.

Posted by: VaccaRabite May 16 2019, 11:10 AM

QUOTE(injunmort @ May 16 2019, 01:02 PM)

Posted by: Optimusglen May 16 2019, 11:32 AM

Fan is solid on the hub, that was the first think I checked, doesn't move at all except of course rotating.

Posted by: tejon007 May 16 2019, 01:56 PM

Sounds like the alternator needs some attention...maybe even the alternator mount is loose or broken.

Posted by: Dave_Darling May 16 2019, 04:57 PM

Pull the alternator belt and see if the noise stops. If so, the alt is your number one suspect.

--DD

Posted by: michael7810 May 16 2019, 04:57 PM

Almost sounds like a bad exhaust leak...but my hearing ain’t so good

Posted by: Optimusglen May 17 2019, 07:56 AM

Parked it until I can dive into it more. The pulley on the alternator had some slop even though the bolt was tight, so that will be the next thing I look into and pull the belt and see how it sounds. I'll also check the exhaust since I did recently install a new aftermarket muffler and since you mentioned exhaust leak, no harm in checking it out.

Posted by: Optimusglen May 25 2019, 09:50 PM

Fun stuff. And not fun stuff.

Ordered a new alternator, just the regular 55w one. Spent the afternoon swapping it in. In the process of pulling the old one out an ACORN fell out of it. Screwy. But, the pulley was loose even though the bolt was tightened down, the key was a bit mangled and the slot in the old alternator shaft was even more mangled so it was good I had a new one.

Got everything buttoned up, went to connect the battery and suddenly there's billowing smoke.

:[

Pull the battery cable and push it out into the driveway. Later climbed under and the alt harness is melty goo. Guessing a short to the alt back plate?

New harness from 914Rubber on order. Anyone know if that type of thing would fry other components?

Oh, and I installed a new alt cooling snorkle. The spring clip unsprung into the fan housing. Anyone with a good method of removing it?

Posted by: mcswiggs May 26 2019, 01:10 AM

Take the back plate off and check the length of the terminal studs and how close they are to that back plate when assembled. I know this is a problem on new alternators sold in the UK to bus owners. Good luck.

QUOTE(Optimusglen @ May 25 2019, 09:50 PM)

Posted by: Mark Henry May 26 2019, 05:31 PM

Did you put 911 valve adjusters on it? Some are real long and will hit the valve covers.

Posted by: Optimusglen May 28 2019, 08:18 AM

No 911 valve adjusters.

Back onto the alternator discussion. I may have hooked the alternator condenser up to the wrong post when replacing it this past weekend.



I have yet to pull it out, but thinking back it is possible. The new alt had longer posts and I knew enough to cut those down. The alternator wiring harness was old and not in the best shape but looked to be solid and in one piece, and since it was working well before I didn't swap it out. I suppose another possibility is that the harness cracked and created a short while I was moving it around during removal/installation.

Either way, from my initial review it looks like there was a short and it melted the harness. I already ordered a new harness from 914 Rubber. From my research it is likely the alternator is toast too. I'm hoping those and some self respect, if I did miswire it, are the only casualties here.

Posted by: Optimusglen May 30 2019, 03:57 PM

Update, swapped on alternator #3 on with a new harness from 914Rubber. Works like a charm and runs quiet. So the rattle was definitely from alternator #1. Probably a combination of the acorn inside and the sloppy pulley.