Club G40 Forum

Technical => Superchargers / G-Lader => Topic started by: mr. clive on September 01, 2011, 10:09:34 PM

Title: intermittent knocking charger noise ??
Post by: mr. clive on September 01, 2011, 10:09:34 PM
hi guys my charger has suddenly started making unhealthy sounding knocking noises,
i heard it after i started the car so i got out, opened the bonnet for a look,
gave the throttle a little blip with my hand and it stopped.
i thought nothing of it and drove about a mile back to my house,
as i was parking it  started again briefly and then stopped again.

any ideas??

cheers, chris
Title: Re: intermittent knocking charger noise ??
Post by: samg40 on September 01, 2011, 11:26:12 PM
Are you running toothies? If the belt is slack they sometimes 'slap' at idle but sound ok when the revs rise.
Title: Re: intermittent knocking charger noise ??
Post by: grungeisdead on September 01, 2011, 11:53:50 PM
have you ever had the charger serviced in your ownership, or have any history relating to any charger rebuilds.

if you havent, now is probably a good time to split, inspect and replace all bearings and seals. luckily its easy to do, PeteG40 sells all the rebuild gear and has even put up a guide showing all required steps!

but id be doing the following

-check belt tension
-remove belt
-spin engine by hand listening for any unsettling noises
-same with the alternator
-same with the charger
-check the torque of the bolts holding the crank, alternator and charger pulleys

i'd be whipping the charger apart to have a look but then
refit or replace charger belt(s)
tension belt with a friend and a breaker bar on the charger plate 1/2" drive hole

my toothed belts have become slack and caused a slapping noise, the alternator has come loose on its mounts and knocked against the ARB mount,as well as causing the belt to loose tension!

good luck!
Title: Re: intermittent knocking charger noise ??
Post by: mr. clive on September 02, 2011, 07:17:48 PM
had a look today and i notice the belt is quite slack, but i went tension it only to discover its at the max adjustment and you cant get a nice taught belt, the belt is brand new so im guessing ive got the wrong size belt??
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 02, 2011, 11:19:45 PM
1040x8x20's the commonest belt size, however some kits used a 1000mm which is a bit harder to find.
Title: Re: intermittent knocking charger noise ??
Post by: AlexG40 on September 03, 2011, 09:07:14 AM
Quote from: mr. clive on September 02, 2011, 07:17:48 PM
had a look today and i notice the belt is quite slack, but i went tension it only to discover its at the max adjustment and you cant get a nice taught belt, the belt is brand new so im guessing ive got the wrong size belt??

Mine was like that too, try adjusting using the small amount of play in the alternator, it's not much but it all helps.
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 03, 2011, 10:11:31 AM
Size will be on the belt.
Title: Re: intermittent knocking charger noise ??
Post by: mr. clive on September 03, 2011, 12:50:45 PM
ive had a look and i cant seem to get any adjustment on the alternator.

and the markings on the belt have warn away, ant other ways of telling the size?

its a toothed belt  with a 65mm pulley by the way

started it up thismorning and let it idle, and there where no odd noises, just sounded sweet to me :s
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 03, 2011, 12:54:33 PM
they alloy or steel pullies?
Title: Re: intermittent knocking charger noise ??
Post by: mr. clive on September 03, 2011, 01:03:18 PM
there alloy,
i have noticed the teeth on the charger pulley are wearing,
could this be causing any problems ?
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 03, 2011, 04:53:00 PM
Tell size by counting teeth then multiply by 8(pitch in mm). IE 1040 belt will have 130 teeth, 1000 belt will have 125.
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 03, 2011, 06:47:01 PM
if they are alloy 99% sure they will be psd ones and take  a 1040 8m belt.

are you sure your belt has all the teeth... they make a shit sound on idle with a few teeth missing

pete
Title: Re: intermittent knocking charger noise ??
Post by: ereeiz on September 05, 2011, 10:13:51 AM
Mine is on the max. adjustment with a 1040 belt and it's only just enough to tension it, I'm going to look at getting a slightly shorter one and see how that fairs. I've done about 5-6k miles in the past 2months on it with no issues though.
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 05, 2011, 11:53:51 AM
there is a weeeeny bit of play in the alternator, which can make the difference between slack and tight...

shorter belts are very hard to get hold of... ive tried!
Title: Re: intermittent knocking charger noise ??
Post by: samg40 on September 05, 2011, 11:58:47 AM
Yep dont underestimate the alternator adjustment. I struggled to get my belt tight and adjusting the alternator for max tightness made the belt a lot tighter.
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 06, 2011, 11:56:44 AM
1000mm belts are still around, but as Pete says, hard to find. Beeline Engineering products  list a 1000mm Gates belt which is quality and BearingBoys offer one by Medway who I've never heard of for not a lot of money. Having said that, these belts are all manufactured to an ISO, so should be OK.
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 06, 2011, 12:01:32 PM
its not 1000 belts - these dont fit with PSD kits in my experience, 1016 or 1024 belts are the b1tch to get hold of!
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 06, 2011, 01:03:02 PM
I've got a 1000mm belt of unknown make that runs just fine, from local supplier. Got it when the 1040 was too long for the charger/intercooler pipe but solved that problem before the smaller belt arrived.
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 06, 2011, 01:39:10 PM
john - runs fine on a psd kit? or are yours german steel ones?
Title: Re: intermittent knocking charger noise ??
Post by: scotsjohn on September 06, 2011, 03:24:21 PM
An alloy phase 2  psd kit Pete. Tooth profile is the same curvilinear as the 1040 Conti I'm using. I'll have a word with the supplier and see what make it is . Can't see why it wouldn't work though as every thing's just a multiple of the 8mm pitch. It did cost about £20 iirc.
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 06, 2011, 03:33:19 PM
fair dos... weird as when i tried a 1000 8m on mine it was miles too small with a psd kit!  think they must be arange of varying factors (charger piping, alternator setting etc etc)
Title: Re: intermittent knocking charger noise ??
Post by: Thomas on September 06, 2011, 03:44:26 PM
Heres a list of cars with belts that should work i reccon.
Alternator belt OEM 9.5X1000 MM
Ford Granada
Ford Sierra
Mercedes 190
Mercedes 190E
Mercedes 230CE
Mercedes 230E
Opel Vectra
Saab 900
Fiat 127
Ford Taunus
Mercedes 200T
Opel Omega
Saab 99


Alternator belt OEM 9.5X1025 MM
BMW 316i
BMW 318i
Citroen Visa
Citroen XM
Saab 95
Saab 96
BMW 518i
Opel Omega
Title: Re: intermittent knocking charger noise ??
Post by: PeteG40 on September 08, 2011, 07:26:52 AM
those alternator belts will be  V belts wont they? not toothed belts??? as toothed belts are 20mm wide and 8mm toothed pitch


however where did you get that info from? would be interesting to know!
Title: Re: intermittent knocking charger noise ??
Post by: G40supercharged on September 08, 2011, 08:53:28 AM
You could swap the fixed G40 alternator arm for a normal MK3 Polo adjustable one. I think it has a toothed adjustment on it so it would also be easier to set the belt tension using the alternator rather than the charger.