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stevemac

Noisy supercharger

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Since I recently (April) had my 'charger modified to R1 spec, it seems to have developed a strange noise.

 

When I start the car from cold the charger is quiet. After a few minutes, when it starts to warm up, at idle it rattles like a loudish "bag of spanners". When fully warmed up, it screams VERY LOUDLY.

The noise (even at idle rpm) when hot is like an extremely LOUD faulty bearing whine.

 

I kept the revs below 3k for the first 500 miles and after 1k miles, I fitted a 65mm pulley & shorter (genuine Audi/VW) belt.

 

It has taken me a while to locate exactly where this noise was coming from (due to the volume) & mpg is now starting to drop.

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since having mine rebuilt to stage 4 i was surprised by the extra noise not rattley but it does scream

funky

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doesn't sound healthy steve. where was it rebuilt? did they send you the old bearings/strips back with the charger to prove they were replaced? if you were in north america i'd say send it to kk for a free inspection. maybe darren/g-werks over there can take a look at it for you.. you don't want that thing grenading if you just paid for a rebuild, they won't warrantee it, you put a small pulley on. :?

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More noise is to be expected but this sounds to me like a faulty bearing. The rattle (at idle) when the engine is warming up is clearly audible both inside and outside the car & makes it sound like a right "shed". It is this rattle which concerns me & makes me think there is a problem. The rattle sounds very much like a faulty bearing.

 

The sound when hot is very similar in volume & tone to an old "air raid" siren as used during WW2.

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doesn't sound healthy steve. where was it rebuilt? did they send you the old bearings/strips back with the charger to prove they were replaced? if you were in north america i'd say send it to kk for a free inspection. maybe darren/g-werks over there can take a look at it for you.. you don't want that thing grenading if you just paid for a rebuild, they won't warrantee it, you put a small pulley on. :?

 

Didn't get any of the old parts back at all.

 

If this thing blows before I can take it back - they WILL warranty it (I can be very persuasive when I need to be). They fit smaller pulleys & re-chips in their own workshop.

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They fit smaller pulleys & re-chips in their own workshop.

 

Yes, THEY fit them in their workshop. they can gaurantee their own work, not yours. They will say no. They have done it many times before. On my receipt from Jabba it states no warrantee where a pulley smaller thatn 68mm has been used without being reccommended by them. Its a contract. you break it tough.

 

Becuase it sounds like a bearing they may check it out of good will but they may also say it was because you fitted a smaller pulley. wouldnt hurt to ask...

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May I suggest that you put the old pulley back on and then take it back the workshop.

 

Surely they wouldn't be using a different bearing for their chargers that would have the smaller pulley fitted compared to a rebuild for someone else.

 

John

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no the bearing itself wouldnt be different... basically its a clause they include so that if people fit tiny pulleys, the rebuilder is not liable for any damage caused. like john said.. fit the old pulley and take it back right away. i wouldn't drive it at all.

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How much shorter than standard was the belt you used? I had a tensioner cap when I fitted the 68mm pulley. I am convinced the tension was too high and that wore out the pulley side bearing. The same as doing up the alternator belt too tight would wear the bearings in the alternator.

 

A quick home rebuild, a std tensioner and alls well now. No slippage either. I reckon the pulley bearing has probably gone. Jabba may sort you out with that. The bearing on its own isn't too costly, it may have been a bad one?

 

Gavin

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Can't remember exactly but the belt is approx 25mm shorter than standard. Using standard tensioner & idler pulleys.

Replaced all pulleys approx 3 weeks ago (idler pulley, tensioner pulley & cambelt tensioner pulley) as part of my diagnosis.

 

"dubster82" - Charger pulley is 68mm and not 65mm as I thought, so warranty is still valid.

 

I'll re-post in a couple of days, after I've had chance to speak to the company who did the rebuild.

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belt should be gates 68416 for a 68mm pulley and no tensioner mods...

 

The belt that I fitted was standard equipment on an Audi 80 a few years ago. Identical in every way to the original G60 belt, just over 20mm (may have been 22 or 23mm) shorter. Tension looks good, although this belt is possibly still very slightly too long.

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Got car back from garage on Monday evening.

 

After just over an hours worth of diagnosis they came to the decision that my waterpump was at fault & replaced it.... :)

 

Unfortunately, this has made very little or no difference whatsoever to either the rattling while the engine is warming up or the loud bearing whine when the engine is hot..... :(

 

I'm gonna strip the engine this weekend for some in-depth diagnosis !!... :?

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so they did the water pump and nothing changed? :?

 

are you sure its even the charger?

 

regarding belt tension.. you should be able to twist the belt 90 degrees.. not much less, not much more.

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so they did the water pump and nothing changed? :?

 

are you sure its even the charger?

 

Method of elimination means that it is definintely connected to the wide "poly v-belt" also known as a "mono belt". It is definitely not the alternator (checked), tension or idler pulley (both changed), waterpump (now changed). When the engine is run without any belts connected (except for cambelt) the noise stops. When I remove the power steering belt the noise is still there.

Engine was stripped of all ancilleries, pulleys & belts then rebuilt 6 weeks ago - noises are still there !!

 

 

regarding belt tension.. you should be able to twist the belt 90 degrees.. not much less, not much more.

 

Quite correct for a cambelt, however the "poly v-belt" has a spring loaded self tensioning device.

 

The noises as detailed above are apparent even when the standard pulley & brand new original VW belt are refitted.

 

Am I certain it's the charger at fault - well no, not 100% which is why I (fully qualified mechanic BTW) plan to strip the engine again this weekend. The charger rebuilders are also professionals and I am prepared to respect that fact. All I can say, in this instance is that their diagnosis was incorrect. What they have done, however, is to agree with me that the other items connected to the same belt are all okay. Maybe I've missed something, none of us are perfect - I hope I have because then it will be easy to solve. What I can say is that it is unlikely to be a problem with the items listed above as being checked/changed (although I will be re-checking everything because I'm starting to get a bit paranoid)

 

History

The rattling noise originally began a few days after having the charger modified (7 weeks after buying the car), the bearing whine began a couple of weeks after that. At the time I just thought that a different part had started to fail. The noises have gradually got louder as time has gone by.

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