Thunk Sound In Tranny?

[Chas&George]

Hi. My Father's 2003 LS460 makes a strong sounding "thunk" under acceleration for about 3 years now. He always complained about it, but recently heard it myself. Usually happens in higher gears but never in OD....and occurs when the car seems to "not be able to decide" between the highest two gears when not in OD. Two service mgrs at two dealerships heard it and are stumped with the thumps. Any ideas? I seached and found advice with a drain and replace using the Toyota fluid...this was done. Still have noise. Anyone have this issue..or advise?

George is in Boston area, I'm in DC.

Chas

[90LS400Lexus]

Strange... I have never heard of this before on the LS's. Is the car still under warranty? If so, I would demand a new transmission before warranty runs out.

I am sure more here may have some insight on this.

Good luck!

[Chas&George]

Yes, the warranty is long gone at 130k miles. Car is mint condition still. I'll keep reading on here.

[nc211]

Sounds like a possible tranny mount. not a bad repair, and at those miles, i wouldn't be one bit suprised if it's due for replacement. Engine mounts might be getting there too, espeicially under those winter conditions up there. By the way, it's not the LS460, it's the 430. The 460 is the brand new one that came out last year.

Or, time for a tranny fluid replacement at the dealer.

[cardona6569]

Take it to a reputable Tranny shop and check the Torque converter, the mount and changing the fluid is not a bad idea with the filter. But to me it should not be the mount since it has been there 3 years, unless the mount came bad from the factory, not unheard either. Start the checks until you find it. It also seems something mechanical since no other functions have been affected, it is either something broken, loose or internal in the tranny and in the longrun/shot check the front suspencion, strut rods. Try to run the car and without ac radio open windows determine from where it comes. By doing this the Techs can reach a faster conclusion. Record at what speed or when it happens exactly and what conditions. If nothing works use a tranny treatment, and ask in the tranny shops which is the best they have used.

CPR