A4 1.8T Rattle

[recomdos]

Hi,

Quick question a friend at work has a A4 1.8T and on starting it up there is a weird 'knocking/rattle' then it is quiet for a bit, though she says it does come back a bit later on whilst out on the road.

A garage (might have been a dealer) has looked at it and she said they replaced the oil pump - still to no avail this has not fixed the problem.

Any ideas what it could be off hand? I know my description is not exactly thorough - but I don't really know much more info other than that! :S I have not even seen it yet! So I don't know if it's a B5 or B6, though she says it's on a 'Y' plate.

Oh and does anyone know where the diagnostics port is on one of these - I offered to do a vagcom for her anyway.

Cheers,

Rob /ubbthreads/images/graemlins/smile.gif

 

[jaymarwa]

My brother in law has a similar problem on his car. It turned out to be a loose bolt which had a largish washer that caused the rattle.

Worth checking out whether all bolts etc are fully tightened.

 

[The911SC]

I think I heard about this before and it is the ABS doing a diagnostic on the brakes.?..nothing to worry about.
The obd port is under the driver footwell.

 

[simon_golf_tt]

I think there is something in the head that rattles briefly on startup until the oil pressure gets up and it's therefore perfectly normal. I can't remember what this 'thing' is, but I'm pretty sure it's only on newer 1.8T engines i.e. not ones in the B5. I know mine does it for a few seconds on startup and it worried me until I read about it somewhere - that I have since forgotten!! Do some searches and you'll probably find the info.

However, the rattle after a period of running doesn't sound right. I'd get that checked.

 

[peteA3tdi]

is the car on AVS servicing? if so the oil ways and or sump pick up maybe blocked with crap and sludge so the top end runs dry on start up

 

[markpetty]

Mine had started doing the rattle on startup (lasted about one second, sounded like a diesel) until I got it serviced last week and it went away. I reckon it was something loose on mine like the plastic engine cover or something.

 

[markpetty]

... or actually what peteTDI says sounds about right for mine too, since it went away after servicing and I know they cleaned all the crap out.

 

[recomdos]

hey guys - thanks for the replies! not sure about AVS yet - I will have to ask, but don't see the lady very often (even then it's her fellas' so it might be a while before I find out what's what.) one thing I do know is when they got the last bit of work done she mentioned Halfords!!! They were then thinking of the stealers!!! Has she no brains? heh I advised a specialist.

 

[imported_ZeroK66]

Turbo perhaps? Can cehck for play in the turbo if you took cold air intake pipe off the entrance to the "cool" side of the turbo and check for slack.

Classic sign of a worn turbo would be rattle at start up - just that I assume your car is quite new/low mileage, so unlikely.

 

[simon_golf_tt]

Here is the official explaination about what I was talking about. It's from an Audi Technical Sevice Bulletin:

"The camshaft adjustment is hydraulically actuated and controlled by the engine oil pressure.

If the engine has been turned off for a longer time, the oil pressure drops down and the oil partially flows back into the oil sump.

To assure an efficient camshaft adjustment right after an engine cold start, the oil pressure inside the camshaft adjusters must be built as fast as possible. During this time a rattle or knocking noise may be noticeable.

This noise is normal at an engine cold start and will last until the oil pressure is fully built up which takes about 1-2 seconds.

Do not replace the camshaft adjuster unit(s) for a noise concern as described above.

Replacing the camshaft adjuster unit(s) will not eliminate this noise."