When on local roads in 5th gear @ 1500 RPM, when I give it a little gas (25%), there is slight rattle sound like a bolt vibrating in a coffee can, only muffled.

Sound like it comes from the transmission. Too muffled to be spark knock and the it goes away if I increase the gas to more than 50%. Does the torque converter clutch have plates that can rattle?

Almost like a heat shield vibrating, but it seems to be transmission related. No codes, but I get a trans fault if I shift the trans manually, so I don't shift the trans manually.

It runs great and is getting almost 24 mpg, and it's not a big deal, just wondering if other cars have had a similar noise. The day it breaks I make the call to Jag Specialties, so Don't even care if the diagnosis is terminal.

 

I would check for loose bolts on the torque convertor to flywheel connection.

 

Might it be catalytic convertor core braking up and loose.

 

My first guess would also be the catalytic converter. You're describing the classic symptoms of one going bad....

 

+1.

Had a cat break upon my X308 - that was the sound.

Had a torque convertor break on an XJ40 - it sounded like someone shaking a broken mirror in an old oil can.

Had a centre heatshield break loose on my XK last year - sounded like I'd just got married again and was dragging cans behind the car. Now that was a frightening sound.

Graham

 

It's definitely one of your catalytic converters breaking up. Best to sort it before it breaks up enough to enter the mufflers :-(


When it happened to me, I bought a pair of new, non-OEM cats off ebay quite cheap. They've been great for 5 years and 40,000+ miles !

 

Thanks for the ideas.


I'll slide under it later this week, tap on stuff and check the TC bolts.

 

Last Fall the wife's Subaru had the same sound, went under the car and held the catalytic converter, (while it was cold). It rattled and made a similar sound. We ordered a new exhaust system from font to back, as a soon as we took off the converter three acorns came rolling down with the Cat. A squirrel got up under the car and stored his acorns on top of the converter.

 

Now that's an unusual story! I guess we should all add "check for stored acorns" to our inspection list whenever we're underneath the car....

Did you immediately stop the exhaust work on your Subaru, and were you able to return the components for a refund?

 

No we just went ahead and replaced it. I've had some unusual squirrel damage. We parked our Lexus out in the court one morning and left. came home that afternoon and there was a puddle of gas underneath the car. Lifted the hood and a tree rat chewed the gas line in half, I could not figure out how he was able to chew it in half without the fuel burning his mouth. Our property borders about 500 acres of timber, in the city limits so there nothing thinning the squirrel population.

 

Our Greyhounds always keep the squirrel population on our property in check. They occasionally are able to catch one and usually kill it if they do. They can easily outrun the squirrels but they cannot out-zigzag them. But whenever they manage to chase one into a fenced corner, that squirrel is usually dead meat....

 

smart squirrel,nothing like roasted acorns on a cold winter eve.