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Ends knocking on cold start


Lusso
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This problem has been getting gradually worse over about 6 months. When starting from cold and the car has been left standing overnight, i get a knocking just for a couple of seconds when starting. Is there a seperate filter and gallery which is meant to prevent this happening as it sound as though the oil is not picking up quick enough.

Its going in this Wednesday to an independant but just wondered if any one had experianced the same problem?

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Well i was working on where the noise is coming from top (hydraulic tappets) or bottom (big or little ends) of the engine and mine sound likew the bottom. Im just hoping that an oil change will do the trick

thicker oil will only help a slight top end rattle due to the tappets being oil filled, if you think its big end knock i doubt very much that it will help as a bit of oil isnt going to help wear in the bearings frown.gif

Edited by Figure11
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Sorry I was under the impression they were the tappets (hydraulic cam followers/lifters znaika.gif) if its your big ends then might a thicker viscousity oil be better or proly make little difference since the bearings may have worn frown.gif Having said that is it drinking oil?

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The noise your hearing will be almost cerainly top end rattle.

Bottom end noise will be a low deep noise which if you rev the car will growl or knock even louder even after the first few seconds. Once the engine then gets very hot it will also return again.

Bearings are available for this engine, in standard and two oversizes, but quite honestly if they were worn, then many other things in the engine would be worn also.

Small end noise will not go away within the first few seconds. The pistons need to warm up enough to take up the play in the gudgeon pin, this will take a minimum of a couple of minutes as a general rule.

The V8 engine is pretty much bullet proof in the wear area, although like anything, one or two slip up just to prove the rule. Even so you would have to be very unlucky or have abused the car via its servicing and oil/filter type.

On the next oil change, make sure you use the correct viscosity oil and an original make oil filter, as some cheap ones don't have the correct non-return valve fitted. Don't worry about super expensive long life oils, any machanic worth his sorts will tell you a cheaper grade but quality oil changed twice as often is much better.

Also use a basic adative with a PTFE base. This will not stop the top end chatter on start up, but it will leave a coating over the components and therefore avoid future wear.

Good luck. 169144-ok.gif

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According to my manual the correct oil viscosity for the ABZ engine (1995-99 4.2 V8) is 10w/40 or 15w/40 in warm weather.

The consensus of opinion is that semi-synthetic works best - some have reported heavy oil consumption when using thinner fully synthetics.

You may also want to check your oil level - Mrs NikW's A6 gets tappety if the oil level is very low.

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