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Discussion Starter · #1 ·
Hi,

1600 twin port in early bay camper

I'm having problems with vibration in the fan housing. First noticed it when I started snaping alternator straps at regular intervals a few weeks ago. Though it was cheap straps so I upgraded the strap to a heritage T-strap.

3 weeks ago on A30 near Bodmin fet a bang at the back, throttle cable snapped and engine died. Turned out thet T-strap had fractured with some force (knackering throttle cable and disconnecting the alternator cables). Got it running again but all the tinware loose and a grinding sound in fan housing (sparks and all). Oh, and alternator rotated 45degrees, all 4 mounting bolts in fan housing missing.

Pull it apart after an embarassing RAC recovery, and found that fan had fractured around the centre, slipped a couple of mill out of line and shook itself to death.

Replaced fan with new one from hertiage and new starp. Took it for run for a couple of hours yesterday - strap has snapped again and vibration inside the fan housing. Bummer

There seem to be only four rotating components in that department: pulley, alternator, hub, fan. Not rocket science, but a £200 bill to replace all in one go. Surely the alternator wouldn't set up that kind of vibration (enough to damage the fan) for example?

Or can it?

Can anyone help/advise before the flexible friend get's it?

Rich
 

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Put the fan, alternator, and both halves of the pulley together (off the engine).

Make sure there's no looseness in the alternator bearings.

Hold the alt in a vice or maybe a workmate thats laid on it's side. Remove the regulator and / or brushes so the alt spins freely.

Spin the alt and wait till it comes to a stop. Put a chalk mark on the top of the fan. Repeat a few times - if the chalk marks are all in one spot then something's throwing it out of balance - probably the fan.

Dave.
 

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Discussion Starter · #3 ·
Many thanks. I'll give it a go. But that would be two fans in as many weeks. Is there a better fan than the standard hertitage / JK offering (don't need a high revving fan)
 

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Cheap wobbly pullys can make them do this too, transmitting the vibration through the alternator and making the fan go into strange harmonic viration/self destruction. As your man up there says^^ check for basic ballance first to eliminate obvious faults:)
 

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You need to check the shaft of the alternator is running true first. If it is then fit the fan and see if that is running true. eg I suspect you either have a bent shaft or the shaft is not locating the fan correctly.

(That is if course assuming theres no play in the alternator bearings)
 

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Discussion Starter · #6 ·
Thanks for the advice all. Alternator bearing failure. Wasn't obvious last time. This time you can move the shaft around. Boll***ks.

Thing is it was just over a year old - GSF. So not very happy.

But hey ... found the fault :)
 

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im havin the same problem straps kept snapping , to start with i was useing the empi crome shite ones from gsf after 3 , i brought a just kampers one , that also snaped so i then went for , a new alternator (bosch ) a new fan form machine 7 and a new pulley , just kampers and a new t style strap from machine 7 , guess what it snaped :mad:, i have manged to get a second hand one from m mate original vw from the 1970s and it is much thicker im hoping that does the trick ,what is your fan like because the empi one i had was as true as a clowns bike wheel ! the machine 7 one is not great either
 

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Discussion Starter · #8 · (Edited)
I feel you pain. I guess the lesson I learnt here is don't ignore snapped straps. Did quite a bit of damage. I don't know what the original fan was. The new one is Heritage. Haven't tested it yet. Chicken and egg. Did the fan wreck the alternator or the alterntor wreck the fan? I hate repro parts!! I got an original fan from a scrappy, but when I put it on it was clear some monkey had yanked it off. Had more shimmy than JLo. Had to pull the engine coz the fan housing was damaged as well. So when it goes back in - well... Let's see. But the alternator was pretty wrecked. Only a year old. But out of warranty. Grrrrr...
 
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