Hi, no one else seems to be able to help me with this noise. I have a chattering or rattling noise that is coming from under my car, but only upon deceleration in 4th gear to 30 +/- mph. The noise is absent upon acceleration but present when at 30 and I shift into neutral. It does not seem affected by braking either.

It is so noticeable, that I am getting looks from pedestrians as I pass them. Comically, they have an initial look of envy upon seeing the car, and then puzzlement as they cannot fathom what that noise is.

All I get is guesses when I pull into a service station. I am loath to have a mechanic not versed in Jaguar engineering to rummage about the engine and transmission. I have a service manual, but no one seems interested in following the diagnostic tree it provides. I case you are wondering, I cannot really afford to bring it to a Jaguar dealership.

Any help or pointers will be greatly appreciated. This is the best car I ever owned!

 

Time to get the hands dirty.

My guesses in NO particular order.

If it is in fact under the car, then:

Catalytic convertor unit is rattling, damn they make a noise, easily heard by pedestrians. Simply raise the thing on a hoist, grab a rubber mallet, bang around the cat area, dont be shy, and rattles will be heard if the membrane stuff inside is breaking up.

2 choices, replace the cat, $$, remove it and gut it, cheap, replace it with a standard pipe, $. NOW, your legal/emission market will dictate what you can/should do, not my area of expertise.

Heat shields around the exhaust system rattling. Generally not audible outside the car by pedestrians, close up, yes.

Now under the bonnet:

Heat shield on the exhaust manifold making a sad noise.

Timing chain tensioner (top unit) dead, and top chain rattle, which is quite audible, however, this more audible on the uptake of revs, as apposed to the deceleration cycle.

In the middle:

Torque convertor is rattling, and I am told it is more common than most admit, although I have never had the pleasure.

I would wait for more replies, and search around your area for a Jag Indy shop, there will be one somewhere.

 

i have what sounds like chains being draged behind ,,,is this what you geting?

 

The e-brake cable can rattle too. I must keep the e-brake one click pulled for it not to rattle.

 

I put a cable tie around each lower suspension arm and the brake cable where it crosses that arm to stop the two banging together. I'm pretty sure that fixed one source of rattles.