On a cold startup, I have a slight clunking sound that is not there on a startup when the car is already warmed up. I know the mounts are some kind of vacuum or similar type, so I'm wondering if that is why it only does it when cold.
I have a 66 mustang that always breaks motor mounts and is really easy to diagnose. I just step on the gas with the hood up and can see the motor flop around. I tried this on the TL, and no luck. Its done it since I bought it so I don't have anything to compare it to. Does this sound like a broken mount?
Its an 03 TL S type with 45K miles if it matters.....

 

If you put it in gear, hold the brakes, blip the gas pedal.... and the engine moves a couple of inches or so, then the mounts are ok. I mean, your steering wheel isn't vibrating, is it?
The source of weird sounds is often difficult to trace. Are you sure it's coming from the engine compartment....driver side or passenger.....near the front or near the firewall? Maybe it comes from under the car? Perhaps exhaust related?

 

Motor does move a little, but since its done it since I bought it, I don't know if its normal or not. I'd say its only moving a few inches.
Doesn't sound like exhaust noise I've had in other cars, but again, only had this six months.
I was mainly curious about mounts due to the involvement of vacuum ( at least I think that's what I remember reading??) it only does it when it's been sitting for many hours, so I wonder why it doesn't do it on a restart when the engine is warmed up?

 

If it were the motor mounts, the difference in warm or cold should'nt matter much. The only thing that could possibly change might be the idle speed being higher when cold.

I'm assuming that the clunk sound is when the car is being shifted into gear. Have you checked your tranny fluid level and condition recently....as that may be what you're experiencing ?????

 

I guess I should have explained better. The clunking is only while hitting the starter. It feels exactly like the old mustang I mentioned when it breaks a mount and the motor "bounces" a little while the starter is spinning. Once the key is in the run position, no more noise.
Trans is original, did the 3x3 chg 6 mos ago, seems to be fine.

 

OK, well than maybe if ya got the original mounts....it would be in order to have the vacuum checked for possible problems, perhaps the control solenoid valve for the mount's vacuum assist is malfunctioning. Do ya notice any difference in idle speed when first starting ?

Seems like a rather unusual circumstance when starting ?

 

I think the idle speed is fine. It's a pretty subtle clunk but definitely there. When cold start, anyway...