RATTLING DIESEL

[SIMMY1968]

Hi I have a 2006 x type diesel that has only covered 70k. Previous owners only averaged 6k a year. When I accelerate my engine is rattily. Its fine at idle the noise is only there when I touch the accelerator. Is this something I should worry about or is it common for a old diesel

[Cubist]

Hi There,
I haven't kept a diesel Jaguar so cannot specifically comment but a twelve year old diesel with only 60k on the clock should still be fairly tight but noise level is always a subjective matter. A few questions for you that may help others to come to an opinion: -

• Have you been able to localise the noise e.g. upper or lower end of engine or elsewhere?
  How long have you had the car?
  What kind of mileage do you do and what kind of trips short or long and what kind of speeds?
  Has it been serviced recently?
  Any signs of black smoke from the exhaust while driving under load e.g. on a steep hill?
  Any signs of oil leaks around the engine?
  What kind of fuel performance are you getting?list]
  
  Cheers,
  Cubist

[SIMMY1968]

Noise sounds like coming from upper engine.
Im doing 44 miles a day but previous records show car was only doing 5k a year
No smoke or oil leaks
Around 43 mpg

[J44EAG]

Is this a mechanical or detonation type noise?

Mike

[SIMMY1968]

Not sure what you mean but on idle noise not there only when accelerate. Some forums say it could be AUX Belt tensioner but not sure

[Cubist]

Should be easy to rule the Aux Belt in or out of the equation. Check the belt for any damage, if a pulley is running off centre the belt will show wear on the edges and you may see some separation of the fibres. If the belt appears to be in good condition, check to see if the belt slips on the pulleys without releasing the tensioner - at the very least this should be very difficult to do. If it does slip the pensioner needs some attention. If good so far, next get a suitable socket wrench on the belt tensioner and ease off the tension while trying to spin the tensioner pulley, the idler pulleys and any other pulleys that will move freely e.g. alternator, AC, etc. while feeling for uneven or lumpy rotation and listening for any bearing grumble.

If all clear on these checks then it back to top end of the engine I'm afraid.

[SIMMY1968]

Ok thanks well car goes in today as under warranty. What is worse case sinario?