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Matt
Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 21615
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have An Audi A4 2.00TDi Auto registered Oct 2006 Reg No P60RNR

Customer Question

I have An Audi A4 2.00TDi Auto registered Oct 2006 Reg No P60RNR (private plate) Org RegAJ56DMX Mileage 86700 serviced once a year best long life oil etc cam belt changed about 70K Problem for the last few weeks when the engine is hot I experience very loud crashing noise when I start up the car does start not always start first time and only lasts for a few seconds. Someone said its is the Dual Mass Flywheel, but some one else said DMF not fitted to my model

Can you help
Submitted: 4 years ago.
Category: Audi
Expert:  Matt replied 4 years ago.
Hello

a failed DMF is a possibilty but its not always the dmf.there is a modified thinner clutch plate for this issue and also a software update to reduce the amount of torque when pulling away to prelong clutch service life.

so its worth asking your dealership to check if your car has had this update

also try removing the auxiliary drive belt and turning every pulley and ancillary ( power steering pump , alternator etc) by hand. All should turn easily (with the exception of the AC pump) with no grittyness or wobbly pulleys- If you do find a sticky pump / alternator then it should be replaced or repaired

If the engine is stone cold you can briefly run it with no belts to see if the noise changes or has gone away, this will help show if an ancillary is the issue

Examine carefully the condition of the bottom / crank pulley as these are composite construction with a rubber element and its possible this rubber is breaking up and allowing the two metal portions to move.

Another possibility is the variable valve timing system as this does rely on oil pressure to correctly synchronise your vvti pulley on the end of the camshaft. If the valve has become blocked up then its possible the pulley is rattling about and producing the noise.

If all of this is OK then its possible the issue is with the dual mass flywheel on the other end of the engine, these are constructed in the same way I mentioned for the front pulley but are more prone to problems due to greater heat and larger forces.

If your gearstick is rattling this is another pointer to this being the problem.



Customer: replied 4 years ago.

Thanks but you refer to a thinner clutch plate & the gear stick BUT ITS AN AUTOMATIC


 


You say "run the engine from cold" IT ONLY DOES IT WHEN HOT


 


Can you please look at what I have said in my question

Expert:  Matt replied 4 years ago.
Hello Roger

OK if its an auto then there's no DMF fitted this is for a manual gearbox only

and if the noise only does it from hot then I'd suggest checking the oil level inside the transmission as I suspect its low and its this thats making the noise

You can top up the box through the side fill plug if required and make sure you use the correct oil for your car as the fluids are not all the same. Some manufacturers recommended a change of the type of fluid - Speak to the local dealer and parts dept - they will advise you on the updated fluid to use..

If that’s all OK then check all the electrical connections of the gearbox, remove each connector in turn and spray with contact cleaner. Check that the wiring to the gearbox is in good condition with no chafing or frayed wire

If this is OK then check the selector lever linkage / cable under the car for any broken parts and or missing bolts as if this is coming adrift then it can rub on the car body or just bind up

Then - you should top up if low and re try it - or, if its level is ok - and condition is ok - then the next step is to drain it off - open it up and clean the filters inside -- refill and retry it..
Customer: replied 4 years ago.

The gear box oil was replaced at about 60k with the correct fluid but i will get it checked again

Customer: replied 4 years ago.

Sorry need to add


 


The gearbox has been slow to change up when cold would this help

Expert:  Matt replied 4 years ago.
Hello Roger

that also makes me think that the oil is past its best but its also well worth checking over the conditon of the auxilary driven parts as I've mentioned above

also check for worn mountings - check the tightness of the engine and gearbox mounts and their condition - this is best done by using a jack to take the weight of the engine off the mounts and seeing if any cracks or splits open up in the rubber.Also check the tightness of the mounts bolts

Customer: replied 4 years ago.

The car is fitted with a DMF

Expert:  Matt replied 4 years ago.
Hello Roger

I'm going to opt out here and get another expert involved