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Matt, Mechanical Engineer
Category: Jaguar
Satisfied Customers: 22907
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 2005 XJ6 2.7 sovereign. Two days ago I started the

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I have a 2005 XJ6 2.7 sovereign. Two days ago I started the car up and there was a tinny noise over the engine. The engine ran smoothly but the noise continued. I took it about 500 yards but there was little acceleration. I called the AA OUT and the man said that he thought that it may be exhaust problems, as he had checked the diagnostics and everthing was ok.We went for a drive and the acceleration was ok, and has been throughout today. The noise is still there. There are no loose joints on the exhaust. My local garage has said that the problem may be inside the exhaust system, but are unable to confirm it. Can you help at all please?

Its quite possible that the cataylst inside the exhaust has broken up and may sometimes be clogging the exhaust up

I'd suggest removing the O2 sensors and peering inside to view the cataylst brick as the brick honeycomb should be even with no holes or lumps and bumps

if this is OK then 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.

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