| [ Total Views: 537 | Total Replies: 3 | Thread Id: 14380 ] |
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 tassupervee
A.k.a.: Knob Jockey
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That really hurts doesnt it!
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| posted on October 11th, 2003 at 09:23 AM |
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Screaming Fan on old 1200
Just a curious thing here.
My older, historic F-Vee (Elfin) has the early (1200) type fan with the lesser amount of blades and supposedly the smaller crank pulley. There are no
extra holes anywhere in the fan shroud other than the throttle cable passing thru it and the cable is sleeved in that hole to a tight fit. The stock
oil cooler is in there.
This thing makes the most fantastic screaming whine between 5200 and 6500 RPM. The thing simply sings not unlike a gear whine but the frequency does
not change with RPM, it just gets louder.
Replaying a video taken of the car revealed the scream to be actually louder than the zorst note and this is confirmed by following drivers.
I cannot seem to locate exactly the noise whilst revving the thing up in neutral.
I dont really want to get rid of the noise :thumb but I am curious as to whether anyone has heard of this and found out why?
L8tr
E
Im not a complete idiot, quite a few parts are missing....
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68AutoBug
A.k.a.: Lee Noonan
Aircooled Master
Beetle Restorer - Experience over 138% - YIKES --
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 posted on October 11th, 2003 at 11:56 AM |
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unusual fan/generator noise in 1200cc engine
Never heard of that before... especially as the frequency doen't change only loudness.... although at that engine speed ,the parts involved are
spinning at Very High Revs and the change in revs isn't all that great at that speed.
The only thing I can thing of that can really make a noise and that would be, either the brushes in the generator or the bearings in the generator. I
just looked up one of My 9 VW workshop manuals and the generator does have two ball bearing similar to a 6303ZZ or 2RS. I really don't think it
would be the bearings, but it maybe the fan belt , at that high engine speed & generator speed , the fan belt will be slipping on the generator
pulley... whether it makes a noise I don't know....
regards
Lee Noonan -VW enthusiast since 1962-
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- [size=4]Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY--- [/size]
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 vw54
Super Administrator
Always Waiting 4 Friday
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| posted on October 11th, 2003 at 06:29 PM |
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Talk to Boris at Vintage in Sydney 02-9789-1777, hes raced F Vees and sponsors them as well.
He will explain the fan noise to you
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Baja Wes
Bishop of Volkswagenism
V6 Baja Pioneer
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| posted on October 12th, 2003 at 10:57 AM |
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I'd follow Dave's lead.
But I woulda thought it was the fan belt slipping. When I was plotting fan air flow curves for the vw fans I had real trouble getting the fan belt to
grip at high fan speeds (above 8,000 rpm fan speed) which is what your talking about. The only way we noticed it was fan belt slip is because we were
monitoring the engine rpm and the fan rpm seperately, and could tell when and how much slip occured.
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tassupervee
A.k.a.: Knob Jockey
Custom Title Time!
That really hurts doesnt it!
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| posted on October 12th, 2003 at 08:42 PM |
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Hmmmm valid points.
I have spun up the fan sans belts and the bearings/brushes are virtually silent.
Thing is its almost like a whistling gear whine coming from, say a Hewland F/Ford 'box. The whistle is very consistent and smooth sounding, like
a straight cut gear whine and thats prolly why I tend to discount it as a belt screech.
I could not get the correct length belt at one stage and i had to fit so many shims between the pulleys that the belt was almost running on the pulley
half alignment lugs and it was absolutely guitar string tight and the whine/whistle came in about 200 odd revs lower. Expected with the change in
drive ratio.
We run the belts completely loose, close to the point of flicking off to (hopefully)promote slippage of the fan under accellaration but this makes no
difference.
Curious.
L8tr guys
E
Im not a complete idiot, quite a few parts are missing....
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ratty 63
A.k.a.: Rossco
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| posted on October 31st, 2003 at 11:01 AM |
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fan rubbing?
Without hearing this sound it a little hard to know, but...
I have heard a sound similar to your description in the past and it turned out to be the fan rubbing on the housing. It only made the noise at higher
revs (not as high as you are describing) and required us to move the fan housing slightly, giving the fan a little more clearance (just placing a
little pressure on the top of the fan housing with my hand was enough to stop it from whining
Just a thought.....
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