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Discussion in 'A4/S4 forum(B5 Chassis)' started by jimya4t, Sep 30, 2006.
My a4 1.8t 20v is noisy when i back off the accelorator?
any 1 no what this could be????
what sort of noisy? like a rattley noisey or a popping noisey?
Its like a rattlin sound its only wen i back off the accelorator???
how rattley? tinny kind of rattly or a heavier, more expensive kind?
I assume you think it is engine specific? could it be clunky or is is higher speed rattle?
can you get any idea of where it is coming from i.e bottom end (lower down in engine bay) or top end. does it only happen when on the move or can you replicate it when stantionary and just revving and just backing off?
if you can add anything to that you may get closer to identifying it
Its more of a tinny rattle and you can make the noise when your stationary. the rattle sounds like its coming from near the turbo area or left of the top end.
2 things Get someone to rev it up for you and look at the waste gate actuator see if it is moving freely backwards or forward or moving as the solenoid actuates..you will see if the rod is broken.
2nd pop the pipe off the front of the turbo and feel the turbine shaft with your finger for movment up and down..could be that..!!!
If the turbo..make sure you chaeck the oil feed pipe these block up then starve the turbo of oil...I would replace this pipe anyway if the turbo is broken
I take it you have checked the oil??
Is the noise from cold or hot or all the time..first start???
check the heat shields on that side too..but to be honest would need to hear it to be 100%
I'd go for the heat shield.. If its only when you back off. happens on numerous cars the thing just gets a little loose and vibrates on decel.. its happened on 3 of my cars now. Not happened on my audi yet tho!
me too, heat sheild, there are lots of them and they always come loose at some point.
if you can replicate when statonary then stick your head in and rev!
Thanks alot. al get that checked on saturday by my mechanic.
Id go for the turbo ive had the same problem the noise disappeared after turbo failure and replacement when i examined the old unit the waste gate flap had left the building also check the the wires onto the wastegate solenoid valve there bad for breaking. the noise i had was exactly like heat shield shimmer/ rattle and it done my nut in.
How much do you think a new turbo would cost?
$2500 for a GT28rx upgrade!! : )
www.turboactive tel 01429 294004 £486 plus £56.00 for the feed pipe remember change the feed pipe they also do upgrades for K03 AND KO4 UNITS
would i need to remap it?
not if it is a straight replacement of the standard turbo. no point spending wedge on a brand new Ko3/s, get a recon one from a reputable place.
sure someone on here must have had one done.
make sure it is the turbo first though : 0
If your,e just staying standard KO3 no. Upgrade more than likely to take advantage of increase boost potential. For me standard is fine i aint going racing and and a ten year old machine thats still capable of 140 mph is good for me. If the stanard item lasts another 136 k ill be happy but reckon ill have moved on by then.
u have any joy on saturday is it the turbo did u check the wires at the wastegate soleniod ?
I am interested in this thread as my 1.8T seems to suffering from the same rattle detailed. The actuator rod has been checked and is not broken. Even when the actautor is moved manually there seems to be no recognisable spool from the turbo if the car is also revved. I did run VAG-COM across the car and got a number of fault codes one of which says that the voltage to the throttle sensor is intermittent and low? Anyway with pressure applied to the actuator rod the rattle seems to disappear momentarily. Also all heat sheilds have been checked and are in place.
Have you found out the problem yet?
I would put money on it being a broken wastegate actuator, mine did the same, rattled when decellarating and when revs drop, wait till the engine is cold and you can get your hand down to the actuator rod if its broken it will slop back and forth like a spoon in a coffee pot !
Cheers will check that, i was about to buy a new turbo as my mechanic couldnt find any thing wrong with it.... i dont think he checked that though. cheers
is the waste gate actuator right next to the turbo????
I think you'll find that this rattle is caused by a faulty, broken or loose/unseated spring inside the actuator...
I had the same problem shortly after having my car remapped, it would (and still does) rattle on engine overrun.
It seems to be a common problem since a few people have complained of similar symptoms. It is not a major worry in my opinion since the performance of the car remains unaffected but it is highly annoying since the car sounds knackered!
If you have ruled out all other issues within the engine itself then you may wish to replace the actuator although it is fiddly and you will need to remove the turbo to do it.
Forge do a replacement actuator, you can see it here - http://www.greydevilindustries.com/products/product.asp?id=20544
If the actuator is rattleing beacause of a broken spring there will be no preload on the wastegate valve and the car will not produce any boost
It is on the turbo, underneath it towards the engine block you will see a rod coming off a diaphragm valve thats the actuator
Well av had my head all over the engine bay and it sounds like its coming from the wastegate and the turbo area??? think it could be that???