strange metallic chi chi chi chi rattle on acceleration

its ecu controlled

 

you time the ignition to 6deg btdc @2500 rpm using a timing light if its digifant. its easier to get a mate
to sit in the car and keep the car at 2500rpm while you move the dizzy and hold the timing light.
first get the car up to about 80deg C, swith it off, un plug the blue temp sender (or 4 pin type), start car again and time to the 6 deg. switch car off again, and reconnect the temp sender


check this, check all vac pipes, clean all earths, check for exhaust leaks round the manifold,

by your description it sounds like its probably pinking

 

I thought moving the dizzy on an agg did nothing?

 

chi chi chi you sure its not cha cha cha and brucie isnt hiding in the bay lol

i reckon theres a rattling heat shieod on the exhaust

 

Wrong, it's been tack welded and it ONLY happens UNDER load.

 

Stupid idea but you seem pretty well stuck so.....is the alternator fan catching the alternator housing, the torque of the engine may move it a little if (IF) the alternator is not bolted down properly and/or the thorough bolt has worked loose, maybe the alternator fan bolt is slightly loose ?
just guessing.....

 

you tried timing it up yet?

 

Can't be that, the sound doesn't vary in frequency with the engine RPM.

 

what sensors would affect timing and where can i find them under the bunnet !!

 

have you actually checked the timing yet tho dude?

 

No, I don't know how to, I also don't have a stobe.

If any one would like to post up some pics or diagrams of were to start that would be helpful.

 

borrow or buy a strobe and look in the haynes manual, there was even a how to on here!

 

my golf dose this and had it over two years my brothers a mechanic and just said cause it get louder under load it was just excess fuel being burnt dunno if that right but never had a problem just an 8v quirk i think

 

Could be the half moon plate bolted to gearbox that shields flywheel. It can touch teeth sometimes. I know this because I caught mine the last day going over some branches. 5min later sound when away when it fell off.

 

quick update :

I think im going to take a gamble on it being the exhaust manifold gasket, so this is the job im having done by VW(at discount) on tuesday.

fingers crossed

 

It's the exhaust manifold gasket wait and see.

 

Promise [:^(]?

 

UPDATE:

I had the manifold gasket, downpipe to manifold gasket and inlet gaskets renewed today and the dam thing is still doing it.

so back to square one as they say.

 

wrong

 

i was sure it would be the manifold gasket. rollocks

From the descriptions above I was sure it would either be leaky exhaust manifold or pinking. Severe pinking comes with noticeable loss of power, don't suppose you've had any of this though or you'd have mentioned it. Do golf's ever crack their exhaust manifold?? I had a BMW with cast iron exhaust manifolds and both manifolds developed a crack (through heat stress I assume), sounded very much like pinking. You'd hope the VW mechanics might have noticed that though.

what you need is a friendly rolling road so you can stick your head under the bonnet at 80mph

keep us posted

re timing, there is a guide on here which covers checking the timing on a digi. You will need a strobe though, or at least a borrow of one. You could try retarding it by hand (turning the dizzy with the direction of rotor rotation - clockwise IIRC) and see if that makes any difference. Not a fix but could be helpful for diagnostics. The ECU can only advance (or retard) a limited amount from the intial setting (dizzy position) so if you turn the dizzy enough the ECU won't be able to make up for it and the engine will run retarded