Y33 Droning under load

[rover3l]

The droning sound that I have with my 2000 Anniversary edition (115,000 miles) has gotten worse recently. I have still not been able to track down the source.

It is evident any time the engine is under load and is particularly annoying on the high way at 65 mph and above. When I lift my foot of the gas the sound goes away.

I am suspecting it is exhaust system related (maybe a baffle has broken) although there don't seem to be any leaks. Has anyone experienced anything similar

[paranoidjack]

Fan clutch?

[rover3l]

I don't think it can be the fan clutch as it is always present under load but completely goes away when I back of the gas.

[Skibane]

What kind of condition are the motor mounts in?

[rover3l]

I haven't checked specifically but why would this cause a noise under load only?

To me it sounds like the sort of resonance you would get with a straight through exhaust system. I can't find any leaks in the system which is why I have started to think about something internal in the system having worn out or failed. I don't recall anyone reporting anything similar and so I don't think it is a typical problem for this model

[Skibane]

It might cause a noise under load because when the engine is producing torque, it attempts to rotate against the mounts. If the mounts are worn out, the engine and transmission are free to rotate enough to come in contact with other body parts, or to stretch wiring and hoses enough to transmit engine noise to the body. Also, when the rubber in the mounts gets old and hard, it transmits more engine noise to the body.

[rover3l]

The noise has increased this last week so hopefully it should be easier to detect the source. I am still leaning towards transmission or exhaust / cat's. Here is why.

I have experimented on the highway with the cruise on say at 65 mph. The drone / resonance is present. As soon as I put it out of gear or kill the cruise the noise goes away. From member's experience are the cat's the most likely place to have "sprung a leak" or are other areas of the exhaust system more likely?

Could the auto transmission make this sort of noise. I am only thinking in this direction as when I take off from a stop there is a sort of fluttering type of noise until I get up to speed. I guess this could also be an exhaust system leak.

The transmission shifts smoothly apart from the hard 1 - 2 shift when very cold