Grrrrrr

Grrrrrr

Technician, Bodgit & Scarper Ltd
Full Member
I've got a mystery hum that starts around [cough]ty miles per hour. I tried removing the wipers because I thought it was coming from the driver's one but on closer investigation it appears to be coming from the centre vent! It appears that when I get above a certain speed (wind direction dependent) a resonance is setup and I get a hum. Closing or opening the airflow from the vent makes no difference.

Any idea what might be causing that? I cannot remember if I have any of that sponge stuff in the intake area or not but surely it wouldn't make that much difference?
 
The rubber round the windscreen? Hmmm. Not quite dark so will take a look ...
 
Well, if I get my fingers under it the front of the trim maybe lifts up a half a millimetre or so?

Those slots in the centre between the bonnet and the windscreen: looks like a shred of black sponge on one side but otherwise clear. Is it supposed to have sponge all the way across?
 
Grrrrrr said:
Well, if I get my fingers under it the front of the trim maybe lifts up a half a millimetre or so?

Those slots in the centre between the bonnet and the windscreen: looks like a shred of black sponge on one side but otherwise clear. Is it supposed to have sponge all the way across?
Click to expand...

Yes, plenium filter, don't know if I spelt it right.:D
 
OK. Seeing as that is clearly missing then I'd better put something across that first, plenum or plenium like. :)
 
Buy two. The foam degrades in sunlight and falls apart within the year.

We need to design and build a stainless steel version...
 
I have the same, bloody cat did it. climbing the screen and slipped taking out the foam, I thought of using a piece of that expanded ali from a Body & paint shop. Cut it to size then spray it matt black. When I get the P38 up and running again that it. Going to Brum I started to get the noise and then I noticed the foam was missing on the nearside. At times its almost like a jet. depends on the headwind. With the metal at least the little **** cannot do it again. He's got the hump since we stopped feeding him, our cat's left overs. Mind you if it puts on too much weight it wont make the bonnet.
 
tnseal said:
I have the same, bloody cat did it. climbing the screen and slipped taking out the foam, I thought of using a piece of that expanded ali from a Body & paint shop. Cut it to size then spray it matt black. When I get the P38 up and running again that it. Going to Brum I started to get the noise and then I noticed the foam was missing on the nearside. At times its almost like a jet. depends on the headwind. With the metal at least the little **** cannot do it again. He's got the hump since we stopped feeding him, our cat's left overs. Mind you if it puts on too much weight it wont make the bonnet.
Click to expand...

1 1/8 oz of lead at high velocity usually stops them.:D
 
I've finally fixed the hum. It turns out it was the air-deflectors behind the front grill. They were missing altogether and until I read the instructions in RAVE I never realised it had them. Fitted air-deflectors and the hum has gone!

The air-deflectors seem to do chuff all for cooling but they do stop resonance at motorway speeds.
 
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